Merge 111429032d into 3e68c7a1c2

Fix modp_b64 search fail when path to ezvcpkg contains a directory named debug

.github/workflows/build.yml

@@ -217,3 +217,70 @@ jobs:
         run: |
           cd build
           ctest -V
+  EmscriptenBuild:
+    strategy:
+      fail-fast: false
+      matrix:
+        version: [ "3.1.39", "4.0.13" ]
+        memory: [ "32", "64" ]
+        exclude:
+          - version: "3.1.39"
+            memory: "64"
+    name: Emscripten v${{matrix.version}} ${{matrix.memory}}bit memory
+    env:
+      CACHE_KEY: "emscripten-${{matrix.version}}-${{matrix.memory}}"
+    runs-on: windows-2022
+    steps:
+      - name: Check out repository code
+        uses: actions/checkout@v4
+        with:
+          submodules: recursive
+      - name: Use NodeJS 24 for WebAssembly 64-bit memory support
+        if: ${{ matrix.memory == '64' }}
+        uses: actions/setup-node@v6
+        with:
+          node-version: '>=24'
+      - name: Checkout vcpkg 2025.02.14 packages for use with Emscripten 3.1.39
+        if: ${{ matrix.version == '3.1.39' }}
+        uses: actions/checkout@v4
+        with:
+          repository: microsoft/vcpkg
+          clean: false
+          ref: 2025.02.14
+          path: extern/vcpkg/temp
+          sparse-checkout-cone-mode: false
+          sparse-checkout: |
+            ports/ada-url
+      - name: Move overlay ports to the correct location
+        if: ${{ matrix.version == '3.1.39' }}
+        run: |
+          mv extern/vcpkg/temp/ports/* extern/vcpkg/ports/
+      - name: Add OpenSSL "no-dso" option on older Emscripten versions
+        if: ${{ matrix.version == '3.1.39' }}
+        run: |
+          echo "
+            if(PORT MATCHES "openssl")
+              set(VCPKG_CONFIGURE_MAKE_OPTIONS "no-dso")
+            endif()
+            " >> extern/vcpkg/triplets/wasm32-emscripten-cesium.cmake
+      - name: Install latest CMake 3 and Ninja
+        uses: lukka/get-cmake@latest
+        with:
+          cmakeVersion: "3.31.6"
+      - name: Install nasm
+        uses: ilammy/setup-nasm@v1
+      - name: Setup emsdk
+        uses: mymindstorm/setup-emsdk@v14
+        with:
+          version: ${{matrix.version}}
+      - name: Verify
+        run: emcc -v
+      - name: Compile Debug Configuration
+        run: |
+          $env:VCPKG_ROOT="$env:VCPKG_INSTALLATION_ROOT"
+          $MEMORYPROPERTY="${{matrix.memory}}" -eq "64" ? "-DCESIUM_WASM64=ON" : ""
+          emcmake cmake -B build -S . -DCMAKE_BUILD_TYPE=Debug $MEMORYPROPERTY
+          cmake --build build --config Debug --parallel
+      - name: Test Debug Configuration
+        run: |
+          node build/CesiumNativeTests/cesium-native-tests.js

.gitignore

@@ -1,4 +1,5 @@
 build
+build-*
 doxygen
 Testing
 node_modules
@@ -8,7 +9,5 @@ CMakeSettings.json
 .cache
 *.DS_Store
 test.db
-build-wsl
 .idea
-build-debug
 clang-tidy.log

CHANGES.md

@@ -1,5 +1,11 @@
 # Change Log
 
+### v0.54.0 - 2025-11-17
+
+##### Additions :tada:
+
+- Cesium Native can now be built with Emscripten.
+
 ### v0.53.0 - 2025-11-03
 
 ##### Breaking Changes :mega:
@@ -13,6 +19,11 @@
 - Added `Uri::ensureTrailingSlash`, which is helpful when the `Uri` represents a base URL.
 - Added `GltfModifier`, which can be used to modify tile glTFs as they load, as well as apply new modifications to them later.
 
+##### Additions :tada:
+
+- Added support for the `KHR_gaussian_splatting` extension.
+  - SPZ payloads for `KHR_guassian_splatting` using the `KHR_gaussian_splatting_compression_spz_2` extension will now be decoded.
+
 ##### Fixes :wrench:
 
 - Fixed a bug in `GoogleMapTilesRasterOverlay` that tried to parse credits from an erroneous viewport service response.

CMakeLists.txt

@@ -4,6 +4,14 @@ if (NOT VCPKG_LIBRARY_LINKAGE)
     set(VCPKG_LIBRARY_LINKAGE static)
 endif()
 
+get_filename_component(toolchainFile "${CMAKE_TOOLCHAIN_FILE}" NAME)
+if(toolchainFile STREQUAL "Emscripten.cmake")
+    set(CESIUM_TARGET_WASM ON)
+    # Include the toolchain directly as ezvcpkg will overwrite the 
+    # toolchain before it's loaded
+    include(${CMAKE_TOOLCHAIN_FILE})
+endif()
+
 # By default, Use ezvcpkg to install dependencies. But don't use
 # ezvcpkg if it appears that this configuration is using vcpkg
 # manifest mode already, either by building cesium-native directly,
@@ -24,6 +32,13 @@ endif()
 
 option(CESIUM_USE_EZVCPKG "use ezvcpkg helper" ${CESIUM_USE_EZVCPKG_DEFAULT})
 option(CESIUM_DISABLE_CURL "Disable cesium-native's use of libcurl" OFF)
+option(CESIUM_DISABLE_LIBJPEG_TURBO "Disable cesium-native's use of libjpeg-turbo. JPEG images will be decoded with STB instead." OFF)
+option(CESIUM_WASM64 "Enable 64-bit WebAssembly target" OFF)
+
+if (CESIUM_TARGET_WASM)
+    # Make sure curl is disabled on wasm builds, as it is not supported.
+    set(CESIUM_DISABLE_CURL ON)
+endif()
 
 if(CESIUM_USE_EZVCPKG)
   # Keep vcpkg from running in manifset mode. It will try to because
@@ -50,6 +65,15 @@ if (NOT VCPKG_TRIPLET)
     elseif(DETECTED_VCPKG_TRIPLET STREQUAL "x64-windows")
         # cesium-native requires static linking on Windows
         set(VCPKG_TRIPLET "x64-windows-static-md")
+    elseif(DETECTED_VCPKG_TRIPLET STREQUAL "wasm32-emscripten")
+        # Use our custom triplet for wasm builds. Most importantly, this
+        # enables multithreading support. Also switch to 64-bit wasm if
+        # requested.
+        if (CESIUM_WASM64)
+            set(VCPKG_TRIPLET "wasm64-emscripten-cesium")
+        else()
+            set(VCPKG_TRIPLET "wasm32-emscripten-cesium")
+        endif()
     else()
         set(VCPKG_TRIPLET "${DETECTED_VCPKG_TRIPLET}")
     endif()
@@ -87,6 +111,10 @@ if (NOT VCPKG_OVERLAY_TRIPLETS)
     endif()
 endif()
 
+if (EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/extern/vcpkg/triplets")
+    list(APPEND VCPKG_OVERLAY_TRIPLETS "${CMAKE_CURRENT_SOURCE_DIR}/extern/vcpkg/triplets")
+endif()
+
 message(STATUS "VCPKG_OVERLAY_TRIPLETS ${VCPKG_OVERLAY_TRIPLETS}")
 
 # These packages are used in the public headers of Cesium libraries, so we need to distribute the headers and binaries
@@ -98,13 +126,13 @@ set(PACKAGES_PUBLIC asyncplusplus expected-lite fmt glm rapidjson spdlog stb ada
 # to distribute the binaries for linking, but not the headers, as downstream consumers don't need them
 # OpenSSL and abseil are both dependencies of s2geometry
 set(PACKAGES_PRIVATE
-    abseil draco ktx modp-base64 meshoptimizer openssl s2geometry
-    libjpeg-turbo sqlite3 tinyxml2 libwebp zlib-ng picosha2
-    earcut-hpp cpp-httplib[core] libmorton zstd
+    abseil draco ktx[core] modp-base64 meshoptimizer openssl s2geometry
+    sqlite3 tinyxml2 libwebp zlib-ng picosha2
+    earcut-hpp libmorton zstd spz zlib
 )
 
-# asmjit needed by blend2d on non-iOS platforms (iOS doesn't support JIT)
-if(NOT IOS AND NOT VCPKG_CMAKE_SYSTEM_NAME MATCHES "iOS")
+# asmjit needed by blend2d on non-iOS platforms (iOS and Wasm don't support JIT)
+if(NOT CESIUM_TARGET_WASM AND NOT IOS AND NOT VCPKG_CMAKE_SYSTEM_NAME MATCHES "iOS")
     list(APPEND PACKAGES_PRIVATE blend2d asmjit)
 else()
     # Use [core] feature to disable default jit feature.
@@ -115,16 +143,37 @@ if(NOT CESIUM_DISABLE_CURL)
     list(APPEND PACKAGES_PRIVATE curl)
 endif()
 
+if(NOT CESIUM_DISABLE_LIBJPEG_TURBO)
+    list(APPEND PACKAGES_PRIVATE libjpeg-turbo)
+endif()
+
+# We use cpp-httplib to host a local web server for OAuth2 authorization. That's not
+# going to work at all on the web, and the latest versions of cpp-httplib only support
+# 64-bit platforms anyway, so skip it entirely for WebAssembly builds.
+if(NOT CESIUM_TARGET_WASM)
+    list(APPEND PACKAGES_PRIVATE "cpp-httplib[core]")
+endif()
+
 # Packages only used for testing
 set(PACKAGES_TEST doctest)
 
+if(CESIUM_TARGET_WASM)
+    # vcpkg will attempt to second-guess our CMAKE_C_COMPILER setting, choosing to go with the value of CC instead.
+    # While normally this is the correct value to go with, for wasm we need to be using emcc and em++.
+    # So we set CC and CXX to emcc and em++ here so vcpkg will pick them up properly.
+    # Does this make sense? No. Does it work? Somehow. ¯\_(ツ)_/¯
+    set(ENV{CC} ${CMAKE_C_COMPILER})
+    set(ENV{CXX} ${CMAKE_CXX_COMPILER})
+endif()
+
 if(CESIUM_USE_EZVCPKG)
     set(PACKAGES_ALL ${PACKAGES_PUBLIC})
     list(APPEND PACKAGES_ALL ${PACKAGES_PRIVATE})
     list(APPEND PACKAGES_ALL ${PACKAGES_TEST})
 
     ezvcpkg_fetch(
-        COMMIT 2025.09.17
+        COMMIT afc0a2e01ae104a2474216a2df0e8d78516fd5af
+        REPO microsoft/vcpkg
         PACKAGES ${PACKAGES_ALL}
         # Clean the build trees after building, so that we don't use a ton a disk space on the CI cache
         CLEAN_BUILDTREES
@@ -145,10 +194,20 @@ endif()
 include("cmake/defaults.cmake")
 
 project(cesium-native
-    VERSION 0.53.0
+    VERSION 0.54.0
     LANGUAGES CXX C
 )
 
+if(CESIUM_TARGET_WASM)
+    if(CESIUM_WASM64)
+        set(CMAKE_SIZEOF_VOID_P 8)
+    else()
+        set(CMAKE_SIZEOF_VOID_P 4)
+    endif()
+    # Tells emscripten to output an HTML harness for the generated WASM
+    set(CMAKE_EXECUTABLE_SUFFIX ".html")
+endif()
+
 include(GNUInstallDirs)
 include(CMakeDependentOption)
 
@@ -318,21 +377,20 @@ find_package(doctest CONFIG REQUIRED)
 find_package(draco CONFIG REQUIRED)
 find_package(expected-lite CONFIG REQUIRED)
 find_package(glm CONFIG REQUIRED)
-find_package(httplib CONFIG REQUIRED)
 find_package(Ktx CONFIG REQUIRED)
-find_package(libjpeg-turbo CONFIG REQUIRED)
 find_package(libmorton CONFIG REQUIRED)
 find_package(meshoptimizer CONFIG REQUIRED)
 find_package(OpenSSL REQUIRED)
 find_package(s2 CONFIG REQUIRED)
 find_package(spdlog CONFIG REQUIRED)
+find_package(spz CONFIG REQUIRED)
 find_package(tinyxml2 CONFIG REQUIRED)
 find_package(unofficial-sqlite3 CONFIG REQUIRED)
 find_package(WebP CONFIG REQUIRED)
 find_package(zlib-ng CONFIG REQUIRED)
 
-# asmjit should not be included with iOS builds as iOS doesn't support JIT compilation.
-if(NOT IOS AND NOT VCPKG_CMAKE_SYSTEM_NAME MATCHES "iOS")
+# asmjit should not be included with iOS or Wasm builds as they don't support JIT compilation.
+if(NOT CESIUM_TARGET_WASM AND NOT IOS AND NOT VCPKG_CMAKE_SYSTEM_NAME MATCHES "iOS")
     find_package(asmjit CONFIG REQUIRED)
 endif()
 
@@ -340,6 +398,14 @@ if(NOT CESIUM_DISABLE_CURL)
     find_package(CURL REQUIRED)
 endif()
 
+if(NOT CESIUM_DISABLE_LIBJPEG_TURBO)
+    find_package(libjpeg-turbo CONFIG REQUIRED)
+endif()
+
+if(NOT CESIUM_TARGET_WASM)
+    find_package(httplib CONFIG REQUIRED)
+endif()
+
 # Private Library (s2geometry)
 add_subdirectory(extern EXCLUDE_FROM_ALL)
 

Cesium3DTilesContent/include/Cesium3DTilesContent/SubtreeAvailability.h

@@ -234,7 +234,7 @@ public:
   bool isContentAvailable(
       const CesiumGeometry::QuadtreeTileID& subtreeId,
       const CesiumGeometry::QuadtreeTileID& tileId,
-      uint64_t contentId) const noexcept;
+      size_t contentId) const noexcept;
 
   /**
    * @brief Determines if content for a given tile in the octree is available.
@@ -247,7 +247,7 @@ public:
   bool isContentAvailable(
       const CesiumGeometry::OctreeTileID& subtreeId,
       const CesiumGeometry::OctreeTileID& tileId,
-      uint64_t contentId) const noexcept;
+      size_t contentId) const noexcept;
 
   /**
    * @brief Determines if content for a given tile in the subtree is available.
@@ -262,7 +262,7 @@ public:
   bool isContentAvailable(
       uint32_t relativeTileLevel,
       uint64_t relativeTileMortonId,
-      uint64_t contentId) const noexcept;
+      size_t contentId) const noexcept;
 
   /**
    * @brief Sets the availability state of the content for a given tile in the
@@ -276,7 +276,7 @@ public:
   void setContentAvailable(
       const CesiumGeometry::QuadtreeTileID& subtreeId,
       const CesiumGeometry::QuadtreeTileID& tileId,
-      uint64_t contentId,
+      size_t contentId,
       bool isAvailable) noexcept;
 
   /**
@@ -291,7 +291,7 @@ public:
   void setContentAvailable(
       const CesiumGeometry::OctreeTileID& subtreeId,
       const CesiumGeometry::OctreeTileID& tileId,
-      uint64_t contentId,
+      size_t contentId,
       bool isAvailable) noexcept;
 
   /**
@@ -309,7 +309,7 @@ public:
   void setContentAvailable(
       uint32_t relativeTileLevel,
       uint64_t relativeTileMortonId,
-      uint64_t contentId,
+      size_t contentId,
       bool isAvailable) noexcept;
 
   /**

Cesium3DTilesContent/src/BatchTableToGltfStructuralMetadata.cpp

@@ -1014,7 +1014,10 @@ void copyStringsToBuffers(
     for (const auto& str : arrayMember.GetArray()) {
       OffsetType byteLength = static_cast<OffsetType>(
           str.GetStringLength() * sizeof(rapidjson::Value::Ch));
-      std::memcpy(valueBuffer.data() + offset, str.GetString(), byteLength);
+      std::memcpy(
+          valueBuffer.data() + offset,
+          str.GetString(),
+          size_t(byteLength));
       std::memcpy(
           offsetBuffer.data() + offsetIndex * sizeof(OffsetType),
           &offset,
@@ -1075,8 +1078,7 @@ void updateStringArrayProperty(
     ++it;
   }
 
-  const uint64_t totalByteLength =
-      totalCharCount * sizeof(rapidjson::Value::Ch);
+  const size_t totalByteLength = totalCharCount * sizeof(rapidjson::Value::Ch);
   std::vector<std::byte> valueBuffer;
   std::vector<std::byte> stringOffsetBuffer;
   PropertyComponentType stringOffsetType = PropertyComponentType::None;

Cesium3DTilesContent/src/PntsToGltfConverter.cpp

@@ -823,7 +823,7 @@ void decodeDracoMetadata(
     const std::unique_ptr<draco::PointCloud>& pPointCloud,
     rapidjson::Document& batchTableJson,
     PntsContent& parsedContent) {
-  const uint64_t pointsLength = parsedContent.pointsLength;
+  const size_t pointsLength = parsedContent.pointsLength;
   std::vector<std::byte>& data = parsedContent.dracoBatchTableBinary;
 
   const auto& dracoMetadataSemantics = parsedContent.dracoMetadataSemantics;

Cesium3DTilesContent/src/SubtreeAvailability.cpp

@@ -281,7 +281,7 @@ void SubtreeAvailability::setTileAvailable(
 bool SubtreeAvailability::isContentAvailable(
     const CesiumGeometry::QuadtreeTileID& subtreeId,
     const CesiumGeometry::QuadtreeTileID& tileId,
-    uint64_t contentId) const noexcept {
+    size_t contentId) const noexcept {
   uint64_t relativeTileMortonIdx =
       ImplicitTilingUtilities::computeRelativeMortonIndex(subtreeId, tileId);
   return this->isContentAvailable(
@@ -293,7 +293,7 @@ bool SubtreeAvailability::isContentAvailable(
 bool SubtreeAvailability::isContentAvailable(
     const CesiumGeometry::OctreeTileID& subtreeId,
     const CesiumGeometry::OctreeTileID& tileId,
-    uint64_t contentId) const noexcept {
+    size_t contentId) const noexcept {
   uint64_t relativeTileMortonIdx =
       ImplicitTilingUtilities::computeRelativeMortonIndex(subtreeId, tileId);
   return this->isContentAvailable(
@@ -305,7 +305,7 @@ bool SubtreeAvailability::isContentAvailable(
 bool SubtreeAvailability::isContentAvailable(
     uint32_t relativeTileLevel,
     uint64_t relativeTileMortonId,
-    uint64_t contentId) const noexcept {
+    size_t contentId) const noexcept {
   if (contentId >= this->_contentAvailability.size())
     return false;
   return isAvailable(
@@ -317,7 +317,7 @@ bool SubtreeAvailability::isContentAvailable(
 void SubtreeAvailability::setContentAvailable(
     const CesiumGeometry::QuadtreeTileID& subtreeId,
     const CesiumGeometry::QuadtreeTileID& tileId,
-    uint64_t contentId,
+    size_t contentId,
     bool isAvailable) noexcept {
   uint64_t relativeTileMortonIdx =
       ImplicitTilingUtilities::computeRelativeMortonIndex(subtreeId, tileId);
@@ -331,7 +331,7 @@ void SubtreeAvailability::setContentAvailable(
 void SubtreeAvailability::setContentAvailable(
     const CesiumGeometry::OctreeTileID& subtreeId,
     const CesiumGeometry::OctreeTileID& tileId,
-    uint64_t contentId,
+    size_t contentId,
     bool isAvailable) noexcept {
   uint64_t relativeTileMortonIdx =
       ImplicitTilingUtilities::computeRelativeMortonIndex(subtreeId, tileId);
@@ -345,7 +345,7 @@ void SubtreeAvailability::setContentAvailable(
 void SubtreeAvailability::setContentAvailable(
     uint32_t relativeTileLevel,
     uint64_t relativeTileMortonId,
-    uint64_t contentId,
+    size_t contentId,
     bool isAvailable) noexcept {
   if (contentId < this->_contentAvailability.size()) {
     this->setAvailable(
@@ -518,7 +518,7 @@ bool SubtreeAvailability::isAvailableUsingBufferView(
   const SubtreeBufferViewAvailability* bufferViewAvailability =
       std::get_if<SubtreeBufferViewAvailability>(&availabilityView);
 
-  const uint64_t byteIndex = availabilityBitIndex / 8;
+  const size_t byteIndex = size_t(availabilityBitIndex / 8);
   if (byteIndex >= bufferViewAvailability->view.size()) {
     return false;
   }
@@ -541,7 +541,7 @@ void SubtreeAvailability::setAvailableUsingBufferView(
   const SubtreeBufferViewAvailability* pBufferViewAvailability =
       std::get_if<SubtreeBufferViewAvailability>(&availabilityView);
 
-  const uint64_t byteIndex = availabilityBitIndex / 8;
+  const size_t byteIndex = size_t(availabilityBitIndex / 8);
   if (byteIndex >= pBufferViewAvailability->view.size()) {
     // Attempting to set an invalid tile. Assert, but otherwise ignore it.
     CESIUM_ASSERT(false);

Cesium3DTilesContent/test/TestSubtreeAvailability.cpp

@@ -67,8 +67,8 @@ void markTileAvailableForQuadtree(
   uint64_t availabilityBitIndex =
       numOfTilesFromRootToParentLevel +
       libmorton::morton2D_64_encode(tileID.x, tileID.y);
-  const uint64_t byteIndex = availabilityBitIndex / 8;
-  const uint64_t bitIndex = availabilityBitIndex % 8;
+  const size_t byteIndex = size_t(availabilityBitIndex / 8);
+  const size_t bitIndex = size_t(availabilityBitIndex % 8);
   available[byteIndex] |= std::byte(1 << bitIndex);
 }
 
@@ -79,7 +79,7 @@ void markSubtreeAvailableForQuadtree(
       libmorton::morton2D_64_encode(tileID.x, tileID.y);
   const uint64_t byteIndex = availabilityBitIndex / 8;
   const uint64_t bitIndex = availabilityBitIndex % 8;
-  available[byteIndex] |= std::byte(1 << bitIndex);
+  available[(size_t)byteIndex] |= std::byte(1 << bitIndex);
 }
 
 using SubtreeContentInput =
@@ -140,17 +140,17 @@ SubtreeContent createSubtreeContent(
           : 0;
 
   std::vector<std::byte> availabilityBuffer(
-      bufferSize + bufferSize + subtreeBufferSize);
+      size_t(bufferSize + bufferSize + subtreeBufferSize));
 
   std::span<std::byte> contentAvailabilityBuffer(
       availabilityBuffer.data(),
-      bufferSize);
+      size_t(bufferSize));
   std::span<std::byte> tileAvailabilityBuffer(
       availabilityBuffer.data() + bufferSize,
-      bufferSize);
+      size_t(bufferSize));
   std::span<std::byte> subtreeAvailabilityBuffer(
       availabilityBuffer.data() + bufferSize + bufferSize,
-      subtreeBufferSize);
+      size_t(subtreeBufferSize));
 
   SubtreeAvailability::AvailabilityView tileAvailability = std::visit(
       GetAvailabilityView{tileAvailabilityBuffer, false},
@@ -486,9 +486,9 @@ TEST_CASE("Test SubtreeAvailability methods") {
     subtree.bufferViews[1].buffer = 1;
     subtree.bufferViews[2].buffer = 2;
 
-    contentAvailabilityBuffer.resize(bufferSize);
-    tileAvailabilityBuffer.resize(bufferSize);
-    subtreeAvailabilityBuffer.resize(subtreeBufferSize);
+    contentAvailabilityBuffer.resize(size_t(bufferSize));
+    tileAvailabilityBuffer.resize(size_t(bufferSize));
+    subtreeAvailabilityBuffer.resize(size_t(subtreeBufferSize));
 
     subtree.buffers[0].byteLength = subtree.bufferViews[0].byteLength =
         int64_t(bufferSize);
@@ -622,18 +622,18 @@ TEST_CASE("Test parsing subtree format") {
     subtreeHeader.jsonByteLength = subtreeJsonBuffer.GetSize();
     subtreeHeader.binaryByteLength = subtreeBuffers.buffers.size();
 
-    std::vector<std::byte> buffer(
+    std::vector<std::byte> buffer(size_t(
         sizeof(subtreeHeader) + subtreeHeader.jsonByteLength +
-        subtreeHeader.binaryByteLength);
+        subtreeHeader.binaryByteLength));
     std::memcpy(buffer.data(), &subtreeHeader, sizeof(subtreeHeader));
     std::memcpy(
         buffer.data() + sizeof(subtreeHeader),
         subtreeJsonBuffer.GetString(),
-        subtreeHeader.jsonByteLength);
+        size_t(subtreeHeader.jsonByteLength));
     std::memcpy(
         buffer.data() + sizeof(subtreeHeader) + subtreeHeader.jsonByteLength,
         subtreeBuffers.buffers.data(),
-        subtreeHeader.binaryByteLength);
+        size_t(subtreeHeader.binaryByteLength));
 
     // mock the request
     auto pMockResponse = std::make_unique<SimpleAssetResponse>(
@@ -711,18 +711,18 @@ TEST_CASE("Test parsing subtree format") {
     subtreeHeader.jsonByteLength = subtreeJsonBuffer.GetSize();
     subtreeHeader.binaryByteLength = subtreeContent.buffers.size();
 
-    std::vector<std::byte> buffer(
+    std::vector<std::byte> buffer(size_t(
         sizeof(subtreeHeader) + subtreeHeader.jsonByteLength +
-        subtreeHeader.binaryByteLength);
+        subtreeHeader.binaryByteLength));
     std::memcpy(buffer.data(), &subtreeHeader, sizeof(subtreeHeader));
     std::memcpy(
         buffer.data() + sizeof(subtreeHeader),
         subtreeJsonBuffer.GetString(),
-        subtreeHeader.jsonByteLength);
+        size_t(subtreeHeader.jsonByteLength));
     std::memcpy(
         buffer.data() + sizeof(subtreeHeader) + subtreeHeader.jsonByteLength,
         subtreeContent.buffers.data(),
-        subtreeHeader.binaryByteLength);
+        size_t(subtreeHeader.binaryByteLength));
 
     // mock the request
     auto pMockResponse = std::make_unique<SimpleAssetResponse>(
@@ -799,14 +799,14 @@ TEST_CASE("Test parsing subtree format") {
     subtreeHeader.jsonByteLength = subtreeJsonBuffer.GetSize();
     subtreeHeader.binaryByteLength = 0;
 
-    std::vector<std::byte> buffer(
+    std::vector<std::byte> buffer(size_t(
         sizeof(subtreeHeader) + subtreeHeader.jsonByteLength +
-        subtreeHeader.binaryByteLength);
+        subtreeHeader.binaryByteLength));
     std::memcpy(buffer.data(), &subtreeHeader, sizeof(subtreeHeader));
     std::memcpy(
         buffer.data() + sizeof(subtreeHeader),
         subtreeJsonBuffer.GetString(),
-        subtreeHeader.jsonByteLength);
+        size_t(subtreeHeader.jsonByteLength));
 
     // mock the request
     auto pMockResponse = std::make_unique<SimpleAssetResponse>(

Cesium3DTilesReader/src/SubtreeFileReader.cpp

@@ -165,12 +165,12 @@ Future<ReadJsonResult<Subtree>> SubtreeFileReader::loadBinary(
   }
 
   ReadJsonResult<Subtree> result = this->_reader.readFromJson(
-      data.subspan(sizeof(SubtreeHeader), header->jsonByteLength));
+      data.subspan(sizeof(SubtreeHeader), size_t(header->jsonByteLength)));
 
   if (result.value) {
     std::span<const std::byte> binaryChunk = data.subspan(
-        sizeof(SubtreeHeader) + header->jsonByteLength,
-        header->binaryByteLength);
+        sizeof(SubtreeHeader) + size_t(header->jsonByteLength),
+        size_t(header->binaryByteLength));
 
     if (binaryChunk.size() > 0) {
       if (result.value->buffers.empty()) {
@@ -207,7 +207,7 @@ Future<ReadJsonResult<Subtree>> SubtreeFileReader::loadBinary(
 
       buffer.cesium.data = std::vector<std::byte>(
           binaryChunk.begin(),
-          binaryChunk.begin() + buffer.byteLength);
+          binaryChunk.begin() + ptrdiff_t(buffer.byteLength));
     }
   }
 

Cesium3DTilesSelection/CMakeLists.txt

@@ -52,7 +52,7 @@ target_link_libraries(Cesium3DTilesSelection
         CesiumQuantizedMeshTerrain
         CesiumRasterOverlays
         CesiumUtility
-        spdlog::spdlog spdlog::spdlog_header_only
+        spdlog::spdlog
 # PRIVATE
         libmorton::libmorton
         draco::draco

CesiumAsync/CMakeLists.txt

@@ -40,7 +40,7 @@ cesium_target_include_directories(
 target_link_libraries(CesiumAsync
     PUBLIC
         CesiumUtility
-        spdlog::spdlog spdlog::spdlog_header_only
+        spdlog::spdlog
         Async++
     PRIVATE
         unofficial::sqlite3::sqlite3

CesiumClientCommon/CMakeLists.txt

@@ -44,6 +44,12 @@ target_link_libraries(CesiumClientCommon
     PRIVATE
         picosha2::picosha2
         modp_b64::modp_b64
-        httplib::httplib
         OpenSSL::Crypto
 )
+
+if (NOT CESIUM_TARGET_WASM)
+    target_link_libraries(CesiumClientCommon
+        PRIVATE
+            httplib::httplib
+    )
+endif()

CesiumClientCommon/src/OAuth2PKCE.cpp

@@ -13,7 +13,6 @@
 #include <CesiumUtility/joinToString.h>
 
 #include <fmt/format.h>
-#include <httplib.h>
 #include <modp_b64.h>
 #include <rapidjson/document.h>
 #include <rapidjson/error/en.h>
@@ -34,6 +33,13 @@
 #include <utility>
 #include <vector>
 
+// Using httplib for the internal HTTP server to receive the OAuth2 redirect URI
+// is certainly not going to work on the web. And cpp-httplib only supports
+// 64-bit platforms, so we can't even build it for 32-bit emscripten targets.
+#ifndef __EMSCRIPTEN__
+#include <httplib.h>
+#endif
+
 #ifdef _MSC_VER
 #pragma warning(push)
 #pragma warning(disable : 4244)
@@ -59,6 +65,7 @@ using namespace CesiumUtility;
 namespace CesiumClientCommon {
 
 namespace {
+#ifndef __EMSCRIPTEN__
 std::string encodeBase64(const std::vector<uint8_t>& bytes) {
   const size_t count = modp_b64_encode_len(bytes.size());
   std::string result(count, 0);
@@ -72,7 +79,7 @@ std::string encodeBase64(const std::vector<uint8_t>& bytes) {
   // in [RFC7636 Appendix A](https://tools.ietf.org/html/rfc7636#appendix-A)
   const size_t firstPaddingIndex = result.find('=');
   if (firstPaddingIndex != std::string::npos) {
-    result.erase(result.begin() + int64_t(firstPaddingIndex), result.end());
+    result.erase(result.begin() + ptrdiff_t(firstPaddingIndex), result.end());
   }
   std::replace(result.begin(), result.end(), '+', '-');
   std::replace(result.begin(), result.end(), '/', '_');
@@ -170,17 +177,28 @@ std::string createAuthorizationErrorHtml(
       exception.what(),
       applicationName);
 }
+#endif // #ifndef __EMSCRIPTEN__
 } // namespace
 
 CesiumAsync::Future<Result<OAuth2TokenResponse>> OAuth2PKCE::authorize(
     const CesiumAsync::AsyncSystem& asyncSystem,
-    const std::shared_ptr<CesiumAsync::IAssetAccessor>& pAssetAccessor,
-    const std::string& friendlyApplicationName,
-    const OAuth2ClientOptions& clientOptions,
-    const std::vector<std::string>& scopes,
-    std::function<void(const std::string&)>&& openUrlCallback,
-    const std::string& tokenEndpointUrl,
-    const std::string& authorizeBaseUrl) {
+    [[maybe_unused]] const std::shared_ptr<CesiumAsync::IAssetAccessor>&
+        pAssetAccessor,
+    [[maybe_unused]] const std::string& friendlyApplicationName,
+    [[maybe_unused]] const OAuth2ClientOptions& clientOptions,
+    [[maybe_unused]] const std::vector<std::string>& scopes,
+    [[maybe_unused]] std::function<void(const std::string&)>&& openUrlCallback,
+    [[maybe_unused]] const std::string& tokenEndpointUrl,
+    [[maybe_unused]] const std::string& authorizeBaseUrl) {
+#ifdef __EMSCRIPTEN__
+  // Currently we just fail the authorization attempt in Emscripten / web
+  // builds. In theory, we can do a more web-oriented authorization flow here
+  // instead.
+  return asyncSystem.createResolvedFuture<Result<OAuth2TokenResponse>>(
+      Result<OAuth2TokenResponse>(
+          ErrorList::error("OAuth2 PKCE authorization is not supported in "
+                           "Emscripten / WebAssembly builds.")));
+#else  // #ifdef __EMSCRIPTEN__
   auto promise = asyncSystem.createPromise<Result<OAuth2TokenResponse>>();
 
   std::shared_ptr<httplib::Server> pServer =
@@ -332,6 +350,7 @@ CesiumAsync::Future<Result<OAuth2TokenResponse>> OAuth2PKCE::authorize(
   openUrlCallback(authorizeUrl);
 
   return promise.getFuture();
+#endif // #ifdef __EMSCRIPTEN__ #else
 }
 
 CesiumAsync::Future<Result<OAuth2TokenResponse>>

CesiumGltf/generated/include/CesiumGltf/ExtensionKhrGaussianSplatting.h

@@ -0,0 +1,121 @@
+// This file was generated by generate-classes.
+// DO NOT EDIT THIS FILE!
+#pragma once
+
+#include <CesiumGltf/Library.h>
+#include <CesiumUtility/ExtensibleObject.h>
+
+#include <string>
+
+namespace CesiumGltf {
+/**
+ * @brief Data defining a 3D Gaussian Splat primitive.
+ */
+struct CESIUMGLTF_API ExtensionKhrGaussianSplatting final
+    : public CesiumUtility::ExtensibleObject {
+  /**
+   * @brief The original name of this type.
+   */
+  static constexpr const char* TypeName = "ExtensionKhrGaussianSplatting";
+  /** @brief The official name of the extension. This should be the same as its
+   * key in the `extensions` object. */
+  static constexpr const char* ExtensionName = "KHR_gaussian_splatting";
+
+  /**
+   * @brief Known values for Optional property specifying how to project the
+   * Gaussians to achieve a perspective correct value. This property defaults to
+   * perspective.
+   */
+  struct Projection {
+    /** @brief `perspective` */
+    inline static const std::string perspective = "perspective";
+
+    /** @brief `orthographic` */
+    inline static const std::string orthographic = "orthographic";
+  };
+
+  /**
+   * @brief Known values for Optional property specifying how to sort the
+   * Gaussians during rendering. This property defaults to cameraDistance.
+   */
+  struct SortingMethod {
+    /** @brief `cameraDistance` */
+    inline static const std::string cameraDistance = "cameraDistance";
+
+    /** @brief `zDepth` */
+    inline static const std::string zDepth = "zDepth";
+  };
+
+  /**
+   * @brief Known values for Optional property specifying the color space of the
+   * spherical harmonics. This property defaults to BT.709.
+   */
+  struct ColorSpace {
+    /** @brief `BT.709` */
+    inline static const std::string BT_709 = "BT.709";
+
+    /** @brief `BT.2020-ITU` */
+    inline static const std::string BT_2020_ITU = "BT.2020-ITU";
+
+    /** @brief `BT.2020-HLG` */
+    inline static const std::string BT_2020_HLG = "BT.2020-HLG";
+
+    /** @brief `BT.2020-PQ` */
+    inline static const std::string BT_2020_PQ = "BT.2020-PQ";
+
+    /** @brief `Display-P3` */
+    inline static const std::string Display_P3 = "Display-P3";
+
+    /** @brief `linear` */
+    inline static const std::string linear = "linear";
+  };
+
+  /**
+   * @brief Optional property specifying parameters regarding the kernel used to
+   * generate the Gaussians. This property defaults to ellipse.
+   */
+  std::string kernel = "ellipse";
+
+  /**
+   * @brief Optional property specifying how to project the Gaussians to achieve
+   * a perspective correct value. This property defaults to perspective.
+   *
+   * Known values are defined in {@link Projection}.
+   *
+   */
+  std::string projection = Projection::perspective;
+
+  /**
+   * @brief Optional property specifying how to sort the Gaussians during
+   * rendering. This property defaults to cameraDistance.
+   *
+   * Known values are defined in {@link SortingMethod}.
+   *
+   */
+  std::string sortingMethod = SortingMethod::cameraDistance;
+
+  /**
+   * @brief Optional property specifying the color space of the spherical
+   * harmonics. This property defaults to BT.709.
+   *
+   * Known values are defined in {@link ColorSpace}.
+   *
+   */
+  std::string colorSpace = ColorSpace::BT_709;
+
+  /**
+   * @brief Calculates the size in bytes of this object, including the contents
+   * of all collections, pointers, and strings. This will NOT include the size
+   * of any extensions attached to the object. Calling this method may be slow
+   * as it requires traversing the object's entire structure.
+   */
+  int64_t getSizeBytes() const {
+    int64_t accum = 0;
+    accum += int64_t(sizeof(ExtensionKhrGaussianSplatting));
+    accum += CesiumUtility::ExtensibleObject::getSizeBytes() -
+             int64_t(sizeof(CesiumUtility::ExtensibleObject));
+    accum += int64_t(this->kernel.capacity() * sizeof(char));
+    return accum;
+  }
+};
+} // namespace CesiumGltf

CesiumGltf/generated/include/CesiumGltf/ExtensionKhrGaussianSplattingCompressionSpz2.h

@@ -0,0 +1,46 @@
+// This file was generated by generate-classes.
+// DO NOT EDIT THIS FILE!
+#pragma once
+
+#include <CesiumGltf/Library.h>
+#include <CesiumUtility/ExtensibleObject.h>
+
+#include <cstdint>
+
+namespace CesiumGltf {
+/**
+ * @brief Compressed data for SPZ v2 primitive.
+ */
+struct CESIUMGLTF_API ExtensionKhrGaussianSplattingCompressionSpz2 final
+    : public CesiumUtility::ExtensibleObject {
+  /**
+   * @brief The original name of this type.
+   */
+  static constexpr const char* TypeName =
+      "ExtensionKhrGaussianSplattingCompressionSpz2";
+  /** @brief The official name of the extension. This should be the same as its
+   * key in the `extensions` object. */
+  static constexpr const char* ExtensionName =
+      "KHR_gaussian_splatting_compression_spz_2";
+
+  /**
+   * @brief The index of the bufferView.
+   */
+  int32_t bufferView = -1;
+
+  /**
+   * @brief Calculates the size in bytes of this object, including the contents
+   * of all collections, pointers, and strings. This will NOT include the size
+   * of any extensions attached to the object. Calling this method may be slow
+   * as it requires traversing the object's entire structure.
+   */
+  int64_t getSizeBytes() const {
+    int64_t accum = 0;
+    accum += int64_t(sizeof(ExtensionKhrGaussianSplattingCompressionSpz2));
+    accum += CesiumUtility::ExtensibleObject::getSizeBytes() -
+             int64_t(sizeof(CesiumUtility::ExtensibleObject));
+
+    return accum;
+  }
+};
+} // namespace CesiumGltf

CesiumGltf/generated/include/CesiumGltf/ExtensionKhrGaussianSplattingHintsValue.h

@@ -0,0 +1,53 @@
+// This file was generated by generate-classes.
+// DO NOT EDIT THIS FILE!
+#pragma once
+
+#include <CesiumGltf/Library.h>
+#include <CesiumUtility/ExtensibleObject.h>
+
+#include <string>
+
+namespace CesiumGltf {
+/**
+ * @brief Optional rendering hints for rendering the 3D Gaussian splats.
+ * Renderers are free to ignore any of these.
+ */
+struct CESIUMGLTF_API ExtensionKhrGaussianSplattingHintsValue final
+    : public CesiumUtility::ExtensibleObject {
+  /**
+   * @brief The original name of this type.
+   */
+  static constexpr const char* TypeName =
+      "ExtensionKhrGaussianSplattingHintsValue";
+
+  /**
+   * @brief Provides a hint specifying how to project the Gaussians to achieve a
+   * perspective correct value. This is a freeform field that defaults to
+   * perspective. See the extension specification for further known types.
+   */
+  std::string projection = "perspective";
+
+  /**
+   * @brief Provides a hint specifying how to sort the Gaussians during
+   * rendering. This is a freeform field defaulting to cameraDistance. See the
+   * extension specification for further known types.
+   */
+  std::string sortingMethod = "cameraDistance";
+
+  /**
+   * @brief Calculates the size in bytes of this object, including the contents
+   * of all collections, pointers, and strings. This will NOT include the size
+   * of any extensions attached to the object. Calling this method may be slow
+   * as it requires traversing the object's entire structure.
+   */
+  int64_t getSizeBytes() const {
+    int64_t accum = 0;
+    accum += int64_t(sizeof(ExtensionKhrGaussianSplattingHintsValue));
+    accum += CesiumUtility::ExtensibleObject::getSizeBytes() -
+             int64_t(sizeof(CesiumUtility::ExtensibleObject));
+    accum += int64_t(this->projection.capacity() * sizeof(char));
+    accum += int64_t(this->sortingMethod.capacity() * sizeof(char));
+    return accum;
+  }
+};
+} // namespace CesiumGltf

CesiumGltf/generated/include/CesiumGltf/ExtensionTextureWebp.h

@@ -22,7 +22,7 @@ struct CESIUMGLTF_API ExtensionTextureWebp final
   static constexpr const char* ExtensionName = "EXT_texture_webp";
 
   /**
-   * @brief The index of the images node which points to a WebP image.
+   * @brief The index of the WebP image.
    */
   int32_t source = -1;
 

CesiumGltf/include/CesiumGltf/PropertyView.h

@@ -2823,7 +2823,7 @@ private:
     }
 
     uint64_t totalLength = stringOffsets.back();
-    result.data.resize(totalLength);
+    result.data.resize(size_t(totalLength));
     for (size_t i = 0; i < strings.size(); ++i) {
       std::memcpy(
           result.data.data() + stringOffsets[i],

CesiumGltf/src/Model.cpp

@@ -44,7 +44,12 @@
 #include <glm/ext/quaternion_double.hpp>
 #include <glm/ext/vector_float3.hpp>
 #include <glm/geometric.hpp>
+#include <glm/gtc/quaternion.hpp> // NOLINT(misc-include-cleaner)
 #include <glm/gtx/norm.hpp>
+// Despite what clang-tidy will say, we *do* actually need this include or we'll
+// get a "missing mat4_cast" error.
+// NOLINTNEXTLINE
+#include <glm/gtc/quaternion.hpp>
 
 #include <algorithm>
 #include <array>
@@ -408,7 +413,7 @@ ErrorList Model::merge(Model&& rhs) {
     std::copy(
         pRhsDefaultScene->nodes.begin(),
         pRhsDefaultScene->nodes.end(),
-        newScene.nodes.begin() + int64_t(originalNodeCount));
+        newScene.nodes.begin() + ptrdiff_t(originalNodeCount));
 
     // No need to update indices because they've already been updated when
     // we copied them from rhs to this.

CesiumGltf/src/PropertyTableView.cpp

@@ -28,7 +28,7 @@ template <typename T>
 PropertyViewStatusType checkOffsetsBuffer(
     const std::span<const std::byte>& offsetBuffer,
     size_t valueBufferSize,
-    size_t instanceCount,
+    uint64_t instanceCount,
     bool checkBitSize,
     PropertyViewStatusType offsetsNotSortedError,
     PropertyViewStatusType offsetOutOfBoundsError) noexcept {

CesiumGltfContent/src/GltfUtilities.cpp

@@ -50,6 +50,7 @@
 #include <algorithm>
 #include <array>
 #include <cassert>
+#include <cstddef>
 #include <cstdint>
 #include <cstring>
 #include <limits>
@@ -1158,8 +1159,8 @@ void deleteBufferRange(
   // Actually remove the bytes from the buffer.
   pBuffer->byteLength -= bytesToRemove;
   pBuffer->cesium.data.erase(
-      pBuffer->cesium.data.begin() + start,
-      pBuffer->cesium.data.begin() + end);
+      pBuffer->cesium.data.begin() + ptrdiff_t(start),
+      pBuffer->cesium.data.begin() + ptrdiff_t(end));
 }
 
 } // namespace

CesiumGltfReader/CMakeLists.txt

@@ -62,6 +62,21 @@ target_link_libraries(CesiumGltfReader
         meshoptimizer::meshoptimizer
         modp_b64::modp_b64
         KTX::ktx
-        WebP::webp WebP::webpdecoder
-        $<IF:$<TARGET_EXISTS:libjpeg-turbo::turbojpeg>,libjpeg-turbo::turbojpeg,libjpeg-turbo::turbojpeg-static>
+        spz::spz
+        WebP::webp
+        WebP::webpdecoder
 )
+
+if(CESIUM_DISABLE_LIBJPEG_TURBO)
+    target_compile_definitions(
+        CesiumGltfReader
+        PRIVATE
+            CESIUM_DISABLE_LIBJPEG_TURBO
+    )
+else()
+    target_link_libraries(
+        CesiumGltfReader
+        PRIVATE
+            $<IF:$<TARGET_EXISTS:libjpeg-turbo::turbojpeg>,libjpeg-turbo::turbojpeg,libjpeg-turbo::turbojpeg-static>
+    )
+endif()

CesiumGltfReader/generated/include/CesiumGltfReader/ExtensionKhrGaussianSplattingCompressionSpz2Reader.h

@@ -0,0 +1,79 @@
+// This file was generated by generate-classes.
+// DO NOT EDIT THIS FILE!
+#pragma once
+
+#include <CesiumGltf/ExtensionKhrGaussianSplattingCompressionSpz2.h>
+#include <CesiumGltfReader/Library.h>
+#include <CesiumJsonReader/JsonReader.h>
+#include <CesiumJsonReader/JsonReaderOptions.h>
+
+#include <rapidjson/fwd.h>
+
+#include <span>
+#include <vector>
+
+namespace CesiumGltf {
+struct ExtensionKhrGaussianSplattingCompressionSpz2;
+} // namespace CesiumGltf
+
+namespace CesiumGltfReader {
+
+/**
+ * @brief Reads \ref CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2
+ * "ExtensionKhrGaussianSplattingCompressionSpz2" instances from JSON.
+ */
+class CESIUMGLTFREADER_API ExtensionKhrGaussianSplattingCompressionSpz2Reader {
+public:
+  /**
+   * @brief Constructs a new instance.
+   */
+  ExtensionKhrGaussianSplattingCompressionSpz2Reader();
+
+  /**
+   * @brief Gets the options controlling how the JSON is read.
+   */
+  CesiumJsonReader::JsonReaderOptions& getOptions();
+
+  /**
+   * @brief Gets the options controlling how the JSON is read.
+   */
+  const CesiumJsonReader::JsonReaderOptions& getOptions() const;
+
+  /**
+   * @brief Reads an instance of ExtensionKhrGaussianSplattingCompressionSpz2
+   * from a byte buffer.
+   *
+   * @param data The buffer from which to read the instance.
+   * @return The result of reading the instance.
+   */
+  CesiumJsonReader::ReadJsonResult<
+      CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2>
+  readFromJson(const std::span<const std::byte>& data) const;
+
+  /**
+   * @brief Reads an instance of ExtensionKhrGaussianSplattingCompressionSpz2
+   * from a rapidJson::Value.
+   *
+   * @param value The value from which to read the instance.
+   * @return The result of reading the instance.
+   */
+  CesiumJsonReader::ReadJsonResult<
+      CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2>
+  readFromJson(const rapidjson::Value& value) const;
+
+  /**
+   * @brief Reads an array of instances of
+   * ExtensionKhrGaussianSplattingCompressionSpz2 from a rapidJson::Value.
+   *
+   * @param value The value from which to read the array of instances.
+   * @return The result of reading the array of instances.
+   */
+  CesiumJsonReader::ReadJsonResult<
+      std::vector<CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2>>
+  readArrayFromJson(const rapidjson::Value& value) const;
+
+private:
+  CesiumJsonReader::JsonReaderOptions _options;
+};
+
+} // namespace CesiumGltfReader

CesiumGltfReader/generated/include/CesiumGltfReader/ExtensionKhrGaussianSplattingHintsValueReader.h

@@ -0,0 +1,79 @@
+// This file was generated by generate-classes.
+// DO NOT EDIT THIS FILE!
+#pragma once
+
+#include <CesiumGltf/ExtensionKhrGaussianSplattingHintsValue.h>
+#include <CesiumGltfReader/Library.h>
+#include <CesiumJsonReader/JsonReader.h>
+#include <CesiumJsonReader/JsonReaderOptions.h>
+
+#include <rapidjson/fwd.h>
+
+#include <span>
+#include <vector>
+
+namespace CesiumGltf {
+struct ExtensionKhrGaussianSplattingHintsValue;
+} // namespace CesiumGltf
+
+namespace CesiumGltfReader {
+
+/**
+ * @brief Reads \ref CesiumGltf::ExtensionKhrGaussianSplattingHintsValue
+ * "ExtensionKhrGaussianSplattingHintsValue" instances from JSON.
+ */
+class CESIUMGLTFREADER_API ExtensionKhrGaussianSplattingHintsValueReader {
+public:
+  /**
+   * @brief Constructs a new instance.
+   */
+  ExtensionKhrGaussianSplattingHintsValueReader();
+
+  /**
+   * @brief Gets the options controlling how the JSON is read.
+   */
+  CesiumJsonReader::JsonReaderOptions& getOptions();
+
+  /**
+   * @brief Gets the options controlling how the JSON is read.
+   */
+  const CesiumJsonReader::JsonReaderOptions& getOptions() const;
+
+  /**
+   * @brief Reads an instance of ExtensionKhrGaussianSplattingHintsValue from a
+   * byte buffer.
+   *
+   * @param data The buffer from which to read the instance.
+   * @return The result of reading the instance.
+   */
+  CesiumJsonReader::ReadJsonResult<
+      CesiumGltf::ExtensionKhrGaussianSplattingHintsValue>
+  readFromJson(const std::span<const std::byte>& data) const;
+
+  /**
+   * @brief Reads an instance of ExtensionKhrGaussianSplattingHintsValue from a
+   * rapidJson::Value.
+   *
+   * @param value The value from which to read the instance.
+   * @return The result of reading the instance.
+   */
+  CesiumJsonReader::ReadJsonResult<
+      CesiumGltf::ExtensionKhrGaussianSplattingHintsValue>
+  readFromJson(const rapidjson::Value& value) const;
+
+  /**
+   * @brief Reads an array of instances of
+   * ExtensionKhrGaussianSplattingHintsValue from a rapidJson::Value.
+   *
+   * @param value The value from which to read the array of instances.
+   * @return The result of reading the array of instances.
+   */
+  CesiumJsonReader::ReadJsonResult<
+      std::vector<CesiumGltf::ExtensionKhrGaussianSplattingHintsValue>>
+  readArrayFromJson(const rapidjson::Value& value) const;
+
+private:
+  CesiumJsonReader::JsonReaderOptions _options;
+};
+
+} // namespace CesiumGltfReader

CesiumGltfReader/generated/include/CesiumGltfReader/ExtensionKhrGaussianSplattingReader.h

@@ -0,0 +1,77 @@
+// This file was generated by generate-classes.
+// DO NOT EDIT THIS FILE!
+#pragma once
+
+#include <CesiumGltf/ExtensionKhrGaussianSplatting.h>
+#include <CesiumGltfReader/Library.h>
+#include <CesiumJsonReader/JsonReader.h>
+#include <CesiumJsonReader/JsonReaderOptions.h>
+
+#include <rapidjson/fwd.h>
+
+#include <span>
+#include <vector>
+
+namespace CesiumGltf {
+struct ExtensionKhrGaussianSplatting;
+} // namespace CesiumGltf
+
+namespace CesiumGltfReader {
+
+/**
+ * @brief Reads \ref CesiumGltf::ExtensionKhrGaussianSplatting
+ * "ExtensionKhrGaussianSplatting" instances from JSON.
+ */
+class CESIUMGLTFREADER_API ExtensionKhrGaussianSplattingReader {
+public:
+  /**
+   * @brief Constructs a new instance.
+   */
+  ExtensionKhrGaussianSplattingReader();
+
+  /**
+   * @brief Gets the options controlling how the JSON is read.
+   */
+  CesiumJsonReader::JsonReaderOptions& getOptions();
+
+  /**
+   * @brief Gets the options controlling how the JSON is read.
+   */
+  const CesiumJsonReader::JsonReaderOptions& getOptions() const;
+
+  /**
+   * @brief Reads an instance of ExtensionKhrGaussianSplatting from a byte
+   * buffer.
+   *
+   * @param data The buffer from which to read the instance.
+   * @return The result of reading the instance.
+   */
+  CesiumJsonReader::ReadJsonResult<CesiumGltf::ExtensionKhrGaussianSplatting>
+  readFromJson(const std::span<const std::byte>& data) const;
+
+  /**
+   * @brief Reads an instance of ExtensionKhrGaussianSplatting from a
+   * rapidJson::Value.
+   *
+   * @param value The value from which to read the instance.
+   * @return The result of reading the instance.
+   */
+  CesiumJsonReader::ReadJsonResult<CesiumGltf::ExtensionKhrGaussianSplatting>
+  readFromJson(const rapidjson::Value& value) const;
+
+  /**
+   * @brief Reads an array of instances of ExtensionKhrGaussianSplatting from a
+   * rapidJson::Value.
+   *
+   * @param value The value from which to read the array of instances.
+   * @return The result of reading the array of instances.
+   */
+  CesiumJsonReader::ReadJsonResult<
+      std::vector<CesiumGltf::ExtensionKhrGaussianSplatting>>
+  readArrayFromJson(const rapidjson::Value& value) const;
+
+private:
+  CesiumJsonReader::JsonReaderOptions _options;
+};
+
+} // namespace CesiumGltfReader

CesiumGltfReader/generated/src/ExtensionKhrGaussianSplattingCompressionSpz2JsonHandler.h

@@ -0,0 +1,48 @@
+// This file was generated by generate-classes.
+// DO NOT EDIT THIS FILE!
+#pragma once
+
+#include <CesiumGltf/ExtensionKhrGaussianSplattingCompressionSpz2.h>
+#include <CesiumJsonReader/ExtensibleObjectJsonHandler.h>
+#include <CesiumJsonReader/IntegerJsonHandler.h>
+
+namespace CesiumJsonReader {
+class JsonReaderOptions;
+} // namespace CesiumJsonReader
+
+namespace CesiumGltfReader {
+class ExtensionKhrGaussianSplattingCompressionSpz2JsonHandler
+    : public CesiumJsonReader::ExtensibleObjectJsonHandler,
+      public CesiumJsonReader::IExtensionJsonHandler {
+public:
+  using ValueType = CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2;
+
+  static constexpr const char* ExtensionName =
+      "KHR_gaussian_splatting_compression_spz_2";
+
+  explicit ExtensionKhrGaussianSplattingCompressionSpz2JsonHandler(
+      const CesiumJsonReader::JsonReaderOptions& options) noexcept;
+  void reset(
+      IJsonHandler* pParentHandler,
+      CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2* pObject);
+
+  IJsonHandler* readObjectKey(const std::string_view& str) override;
+
+  void reset(
+      IJsonHandler* pParentHandler,
+      CesiumUtility::ExtensibleObject& o,
+      const std::string_view& extensionName) override;
+
+  IJsonHandler& getHandler() override { return *this; }
+
+protected:
+  IJsonHandler* readObjectKeyExtensionKhrGaussianSplattingCompressionSpz2(
+      const std::string& objectType,
+      const std::string_view& str,
+      CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2& o);
+
+private:
+  CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2* _pObject = nullptr;
+  CesiumJsonReader::IntegerJsonHandler<int32_t> _bufferView;
+};
+} // namespace CesiumGltfReader

CesiumGltfReader/generated/src/ExtensionKhrGaussianSplattingHintsValueJsonHandler.h

@@ -0,0 +1,38 @@
+// This file was generated by generate-classes.
+// DO NOT EDIT THIS FILE!
+#pragma once
+
+#include <CesiumGltf/ExtensionKhrGaussianSplattingHintsValue.h>
+#include <CesiumJsonReader/ExtensibleObjectJsonHandler.h>
+#include <CesiumJsonReader/StringJsonHandler.h>
+
+namespace CesiumJsonReader {
+class JsonReaderOptions;
+} // namespace CesiumJsonReader
+
+namespace CesiumGltfReader {
+class ExtensionKhrGaussianSplattingHintsValueJsonHandler
+    : public CesiumJsonReader::ExtensibleObjectJsonHandler {
+public:
+  using ValueType = CesiumGltf::ExtensionKhrGaussianSplattingHintsValue;
+
+  explicit ExtensionKhrGaussianSplattingHintsValueJsonHandler(
+      const CesiumJsonReader::JsonReaderOptions& options) noexcept;
+  void reset(
+      IJsonHandler* pParentHandler,
+      CesiumGltf::ExtensionKhrGaussianSplattingHintsValue* pObject);
+
+  IJsonHandler* readObjectKey(const std::string_view& str) override;
+
+protected:
+  IJsonHandler* readObjectKeyExtensionKhrGaussianSplattingHintsValue(
+      const std::string& objectType,
+      const std::string_view& str,
+      CesiumGltf::ExtensionKhrGaussianSplattingHintsValue& o);
+
+private:
+  CesiumGltf::ExtensionKhrGaussianSplattingHintsValue* _pObject = nullptr;
+  CesiumJsonReader::StringJsonHandler _projection;
+  CesiumJsonReader::StringJsonHandler _sortingMethod;
+};
+} // namespace CesiumGltfReader

CesiumGltfReader/generated/src/ExtensionKhrGaussianSplattingJsonHandler.h

@@ -0,0 +1,50 @@
+// This file was generated by generate-classes.
+// DO NOT EDIT THIS FILE!
+#pragma once
+
+#include <CesiumGltf/ExtensionKhrGaussianSplatting.h>
+#include <CesiumJsonReader/ExtensibleObjectJsonHandler.h>
+#include <CesiumJsonReader/StringJsonHandler.h>
+
+namespace CesiumJsonReader {
+class JsonReaderOptions;
+} // namespace CesiumJsonReader
+
+namespace CesiumGltfReader {
+class ExtensionKhrGaussianSplattingJsonHandler
+    : public CesiumJsonReader::ExtensibleObjectJsonHandler,
+      public CesiumJsonReader::IExtensionJsonHandler {
+public:
+  using ValueType = CesiumGltf::ExtensionKhrGaussianSplatting;
+
+  static constexpr const char* ExtensionName = "KHR_gaussian_splatting";
+
+  explicit ExtensionKhrGaussianSplattingJsonHandler(
+      const CesiumJsonReader::JsonReaderOptions& options) noexcept;
+  void reset(
+      IJsonHandler* pParentHandler,
+      CesiumGltf::ExtensionKhrGaussianSplatting* pObject);
+
+  IJsonHandler* readObjectKey(const std::string_view& str) override;
+
+  void reset(
+      IJsonHandler* pParentHandler,
+      CesiumUtility::ExtensibleObject& o,
+      const std::string_view& extensionName) override;
+
+  IJsonHandler& getHandler() override { return *this; }
+
+protected:
+  IJsonHandler* readObjectKeyExtensionKhrGaussianSplatting(
+      const std::string& objectType,
+      const std::string_view& str,
+      CesiumGltf::ExtensionKhrGaussianSplatting& o);
+
+private:
+  CesiumGltf::ExtensionKhrGaussianSplatting* _pObject = nullptr;
+  CesiumJsonReader::StringJsonHandler _kernel;
+  CesiumJsonReader::StringJsonHandler _projection;
+  CesiumJsonReader::StringJsonHandler _sortingMethod;
+  CesiumJsonReader::StringJsonHandler _colorSpace;
+};
+} // namespace CesiumGltfReader

CesiumGltfReader/generated/src/GeneratedJsonHandlers.cpp

@@ -2974,6 +2974,260 @@ ExtensionExtPrimitiveVoxelsReader::readArrayFromJson(
   return CesiumJsonReader::JsonReader::readJson(value, handler);
 }
 
+} // namespace CesiumGltfReader
+// This file was generated by generate-classes.
+// DO NOT EDIT THIS FILE!
+// NOLINTBEGIN(readability-duplicate-include)
+#include "ExtensionKhrGaussianSplattingJsonHandler.h"
+#include "registerReaderExtensions.h"
+
+#include <CesiumGltf/ExtensionKhrGaussianSplatting.h>
+#include <CesiumGltfReader/ExtensionKhrGaussianSplattingReader.h>
+#include <CesiumJsonReader/ArrayJsonHandler.h>
+#include <CesiumJsonReader/ExtensibleObjectJsonHandler.h>
+#include <CesiumJsonReader/IJsonHandler.h>
+#include <CesiumJsonReader/JsonReader.h>
+#include <CesiumUtility/Assert.h>
+#include <CesiumUtility/ExtensibleObject.h>
+
+#include <rapidjson/document.h>
+
+#include <any>
+#include <cstddef>
+#include <span>
+#include <string>
+#include <string_view>
+#include <vector>
+// NOLINTEND(readability-duplicate-include)
+
+namespace CesiumGltfReader {
+
+ExtensionKhrGaussianSplattingJsonHandler::
+    ExtensionKhrGaussianSplattingJsonHandler(
+        const CesiumJsonReader::JsonReaderOptions& options) noexcept
+    : CesiumJsonReader::ExtensibleObjectJsonHandler(options),
+      _kernel(),
+      _projection(),
+      _sortingMethod(),
+      _colorSpace() {}
+
+void ExtensionKhrGaussianSplattingJsonHandler::reset(
+    CesiumJsonReader::IJsonHandler* pParentHandler,
+    CesiumGltf::ExtensionKhrGaussianSplatting* pObject) {
+  CesiumJsonReader::ExtensibleObjectJsonHandler::reset(pParentHandler, pObject);
+  this->_pObject = pObject;
+}
+
+CesiumJsonReader::IJsonHandler*
+ExtensionKhrGaussianSplattingJsonHandler::readObjectKey(
+    const std::string_view& str) {
+  CESIUM_ASSERT(this->_pObject);
+  return this->readObjectKeyExtensionKhrGaussianSplatting(
+      CesiumGltf::ExtensionKhrGaussianSplatting::TypeName,
+      str,
+      *this->_pObject);
+}
+
+void ExtensionKhrGaussianSplattingJsonHandler::reset(
+    CesiumJsonReader::IJsonHandler* pParentHandler,
+    CesiumUtility::ExtensibleObject& o,
+    const std::string_view& extensionName) {
+  std::any& value =
+      o.extensions
+          .emplace(extensionName, CesiumGltf::ExtensionKhrGaussianSplatting())
+          .first->second;
+  this->reset(
+      pParentHandler,
+      &std::any_cast<CesiumGltf::ExtensionKhrGaussianSplatting&>(value));
+}
+
+CesiumJsonReader::IJsonHandler* ExtensionKhrGaussianSplattingJsonHandler::
+    readObjectKeyExtensionKhrGaussianSplatting(
+        const std::string& objectType,
+        const std::string_view& str,
+        CesiumGltf::ExtensionKhrGaussianSplatting& o) {
+  using namespace std::string_literals;
+
+  if ("kernel"s == str) {
+    return property("kernel", this->_kernel, o.kernel);
+  }
+  if ("projection"s == str) {
+    return property("projection", this->_projection, o.projection);
+  }
+  if ("sortingMethod"s == str) {
+    return property("sortingMethod", this->_sortingMethod, o.sortingMethod);
+  }
+  if ("colorSpace"s == str) {
+    return property("colorSpace", this->_colorSpace, o.colorSpace);
+  }
+
+  return this->readObjectKeyExtensibleObject(objectType, str, *this->_pObject);
+}
+
+ExtensionKhrGaussianSplattingReader::ExtensionKhrGaussianSplattingReader() {
+  registerReaderExtensions(this->_options);
+}
+
+CesiumJsonReader::JsonReaderOptions&
+ExtensionKhrGaussianSplattingReader::getOptions() {
+  return this->_options;
+}
+
+const CesiumJsonReader::JsonReaderOptions&
+ExtensionKhrGaussianSplattingReader::getOptions() const {
+  return this->_options;
+}
+
+CesiumJsonReader::ReadJsonResult<CesiumGltf::ExtensionKhrGaussianSplatting>
+ExtensionKhrGaussianSplattingReader::readFromJson(
+    const std::span<const std::byte>& data) const {
+  ExtensionKhrGaussianSplattingJsonHandler handler(this->_options);
+  return CesiumJsonReader::JsonReader::readJson(data, handler);
+}
+
+CesiumJsonReader::ReadJsonResult<CesiumGltf::ExtensionKhrGaussianSplatting>
+ExtensionKhrGaussianSplattingReader::readFromJson(
+    const rapidjson::Value& value) const {
+  ExtensionKhrGaussianSplattingJsonHandler handler(this->_options);
+  return CesiumJsonReader::JsonReader::readJson(value, handler);
+}
+
+CesiumJsonReader::ReadJsonResult<
+    std::vector<CesiumGltf::ExtensionKhrGaussianSplatting>>
+ExtensionKhrGaussianSplattingReader::readArrayFromJson(
+    const rapidjson::Value& value) const {
+  CesiumJsonReader::ArrayJsonHandler<
+      CesiumGltf::ExtensionKhrGaussianSplatting,
+      ExtensionKhrGaussianSplattingJsonHandler>
+      handler(this->_options);
+  return CesiumJsonReader::JsonReader::readJson(value, handler);
+}
+
+} // namespace CesiumGltfReader
+// This file was generated by generate-classes.
+// DO NOT EDIT THIS FILE!
+// NOLINTBEGIN(readability-duplicate-include)
+#include "ExtensionKhrGaussianSplattingCompressionSpz2JsonHandler.h"
+#include "registerReaderExtensions.h"
+
+#include <CesiumGltf/ExtensionKhrGaussianSplattingCompressionSpz2.h>
+#include <CesiumGltfReader/ExtensionKhrGaussianSplattingCompressionSpz2Reader.h>
+#include <CesiumJsonReader/ArrayJsonHandler.h>
+#include <CesiumJsonReader/ExtensibleObjectJsonHandler.h>
+#include <CesiumJsonReader/IJsonHandler.h>
+#include <CesiumJsonReader/JsonReader.h>
+#include <CesiumUtility/Assert.h>
+#include <CesiumUtility/ExtensibleObject.h>
+
+#include <rapidjson/document.h>
+
+#include <any>
+#include <cstddef>
+#include <span>
+#include <string>
+#include <string_view>
+#include <vector>
+// NOLINTEND(readability-duplicate-include)
+
+namespace CesiumGltfReader {
+
+ExtensionKhrGaussianSplattingCompressionSpz2JsonHandler::
+    ExtensionKhrGaussianSplattingCompressionSpz2JsonHandler(
+        const CesiumJsonReader::JsonReaderOptions& options) noexcept
+    : CesiumJsonReader::ExtensibleObjectJsonHandler(options), _bufferView() {}
+
+void ExtensionKhrGaussianSplattingCompressionSpz2JsonHandler::reset(
+    CesiumJsonReader::IJsonHandler* pParentHandler,
+    CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2* pObject) {
+  CesiumJsonReader::ExtensibleObjectJsonHandler::reset(pParentHandler, pObject);
+  this->_pObject = pObject;
+}
+
+CesiumJsonReader::IJsonHandler*
+ExtensionKhrGaussianSplattingCompressionSpz2JsonHandler::readObjectKey(
+    const std::string_view& str) {
+  CESIUM_ASSERT(this->_pObject);
+  return this->readObjectKeyExtensionKhrGaussianSplattingCompressionSpz2(
+      CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2::TypeName,
+      str,
+      *this->_pObject);
+}
+
+void ExtensionKhrGaussianSplattingCompressionSpz2JsonHandler::reset(
+    CesiumJsonReader::IJsonHandler* pParentHandler,
+    CesiumUtility::ExtensibleObject& o,
+    const std::string_view& extensionName) {
+  std::any& value =
+      o.extensions
+          .emplace(
+              extensionName,
+              CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2())
+          .first->second;
+  this->reset(
+      pParentHandler,
+      &std::any_cast<CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2&>(
+          value));
+}
+
+CesiumJsonReader::IJsonHandler*
+ExtensionKhrGaussianSplattingCompressionSpz2JsonHandler::
+    readObjectKeyExtensionKhrGaussianSplattingCompressionSpz2(
+        const std::string& objectType,
+        const std::string_view& str,
+        CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2& o) {
+  using namespace std::string_literals;
+
+  if ("bufferView"s == str) {
+    return property("bufferView", this->_bufferView, o.bufferView);
+  }
+
+  return this->readObjectKeyExtensibleObject(objectType, str, *this->_pObject);
+}
+
+ExtensionKhrGaussianSplattingCompressionSpz2Reader::
+    ExtensionKhrGaussianSplattingCompressionSpz2Reader() {
+  registerReaderExtensions(this->_options);
+}
+
+CesiumJsonReader::JsonReaderOptions&
+ExtensionKhrGaussianSplattingCompressionSpz2Reader::getOptions() {
+  return this->_options;
+}
+
+const CesiumJsonReader::JsonReaderOptions&
+ExtensionKhrGaussianSplattingCompressionSpz2Reader::getOptions() const {
+  return this->_options;
+}
+
+CesiumJsonReader::ReadJsonResult<
+    CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2>
+ExtensionKhrGaussianSplattingCompressionSpz2Reader::readFromJson(
+    const std::span<const std::byte>& data) const {
+  ExtensionKhrGaussianSplattingCompressionSpz2JsonHandler handler(
+      this->_options);
+  return CesiumJsonReader::JsonReader::readJson(data, handler);
+}
+
+CesiumJsonReader::ReadJsonResult<
+    CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2>
+ExtensionKhrGaussianSplattingCompressionSpz2Reader::readFromJson(
+    const rapidjson::Value& value) const {
+  ExtensionKhrGaussianSplattingCompressionSpz2JsonHandler handler(
+      this->_options);
+  return CesiumJsonReader::JsonReader::readJson(value, handler);
+}
+
+CesiumJsonReader::ReadJsonResult<
+    std::vector<CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2>>
+ExtensionKhrGaussianSplattingCompressionSpz2Reader::readArrayFromJson(
+    const rapidjson::Value& value) const {
+  CesiumJsonReader::ArrayJsonHandler<
+      CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2,
+      ExtensionKhrGaussianSplattingCompressionSpz2JsonHandler>
+      handler(this->_options);
+  return CesiumJsonReader::JsonReader::readJson(value, handler);
+}
+
 } // namespace CesiumGltfReader
 // This file was generated by generate-classes.
 // DO NOT EDIT THIS FILE!

CesiumGltfReader/generated/src/registerReaderExtensions.cpp

@@ -16,6 +16,8 @@
 #include "ExtensionExtPrimitiveVoxelsJsonHandler.h"
 #include "ExtensionExtStructuralMetadataJsonHandler.h"
 #include "ExtensionKhrDracoMeshCompressionJsonHandler.h"
+#include "ExtensionKhrGaussianSplattingCompressionSpz2JsonHandler.h"
+#include "ExtensionKhrGaussianSplattingJsonHandler.h"
 #include "ExtensionKhrImplicitShapesJsonHandler.h"
 #include "ExtensionKhrMaterialsUnlitJsonHandler.h"
 #include "ExtensionKhrTextureBasisuJsonHandler.h"
@@ -30,6 +32,7 @@
 
 #include <CesiumGltf/Buffer.h>
 #include <CesiumGltf/BufferView.h>
+#include <CesiumGltf/ExtensionKhrGaussianSplatting.h>
 #include <CesiumGltf/FeatureIdTexture.h>
 #include <CesiumGltf/Material.h>
 #include <CesiumGltf/MaterialNormalTextureInfo.h>
@@ -81,6 +84,9 @@ void registerReaderExtensions(CesiumJsonReader::JsonReaderOptions& options) {
   options.registerExtension<
       CesiumGltf::MeshPrimitive,
       ExtensionExtPrimitiveVoxelsJsonHandler>();
+  options.registerExtension<
+      CesiumGltf::MeshPrimitive,
+      ExtensionKhrGaussianSplattingJsonHandler>();
   options.registerExtension<
       CesiumGltf::Node,
       ExtensionExtInstanceFeaturesJsonHandler>();
@@ -132,5 +138,8 @@ void registerReaderExtensions(CesiumJsonReader::JsonReaderOptions& options) {
   options.registerExtension<
       CesiumGltf::Shape,
       ExtensionExtImplicitCylinderRegionJsonHandler>();
+  options.registerExtension<
+      CesiumGltf::ExtensionKhrGaussianSplatting,
+      ExtensionKhrGaussianSplattingCompressionSpz2JsonHandler>();
 }
 } // namespace CesiumGltfReader

CesiumGltfReader/include/CesiumGltfReader/GltfReader.h

@@ -89,6 +89,13 @@ struct CESIUMGLTFREADER_API GltfReaderOptions {
    */
   bool decodeMeshOptData = true;
 
+  /**
+   * @brief Whether gaussian splatting data are decompressed as part of the load
+   * process, or left in the compressed format according to the
+   * KHR_gaussian_splatting_compression_spz extension.
+   */
+  bool decodeSpz = true;
+
   /**
    * @brief Whether the quantized mesh data are dequantized and converted to
    * floating-point values when loading, according to the KHR_mesh_quantization

CesiumGltfReader/src/GltfReader.cpp

@@ -3,6 +3,7 @@
 #include "decodeDataUrls.h"
 #include "decodeDraco.h"
 #include "decodeMeshOpt.h"
+#include "decodeSpz.h"
 #include "dequantizeMeshData.h"
 #include "registerReaderExtensions.h"
 
@@ -245,7 +246,7 @@ GltfReaderResult readBinaryGltf(
 
     buffer.cesium.data = std::vector<std::byte>(
         binaryChunk.begin(),
-        binaryChunk.begin() + buffer.byteLength);
+        binaryChunk.begin() + (ptrdiff_t)buffer.byteLength);
   }
 
   return result;
@@ -359,6 +360,10 @@ void postprocess(GltfReaderResult& readGltf, const GltfReaderOptions& options) {
     decodeMeshOpt(model, readGltf);
   }
 
+  if (options.decodeSpz && hasSpzExtension(readGltf)) {
+    decodeSpz(readGltf);
+  }
+
   if (options.dequantizeMeshData &&
       std::find(
           model.extensionsUsed.begin(),

CesiumGltfReader/src/ImageDecoder.cpp

@@ -5,7 +5,6 @@
 #include <CesiumUtility/Tracing.h>
 
 #include <ktx.h>
-#include <turbojpeg.h>
 #include <webp/decode.h>
 
 #include <algorithm>
@@ -28,6 +27,10 @@
 #define STB_IMAGE_RESIZE_STATIC
 #include <stb_image_resize2.h>
 
+#ifndef CESIUM_DISABLE_LIBJPEG_TURBO
+#include <turbojpeg.h>
+#endif
+
 namespace CesiumGltfReader {
 
 using namespace CesiumGltf;
@@ -287,6 +290,7 @@ ImageReaderResult ImageDecoder::readImage(
   }
 
   {
+#ifndef CESIUM_DISABLE_LIBJPEG_TURBO
     tjhandle tjInstance = tjInitDecompress();
     int inSubsamp, inColorspace;
     if (!tjDecompressHeader3(
@@ -316,7 +320,9 @@ ImageReaderResult ImageDecoder::readImage(
         result.errors.emplace_back("Unable to decode JPEG");
         result.pImage = nullptr;
       }
-    } else {
+    } else
+#endif // !CESIUM_DISABLE_LIBJPEG_TURBO
+    {
       CESIUM_TRACE("Decode PNG");
       image.bytesPerChannel = 1;
       image.channels = 4;
@@ -349,7 +355,9 @@ ImageReaderResult ImageDecoder::readImage(
         result.errors.emplace_back(stbi_failure_reason());
       }
     }
+#ifndef CESIUM_DISABLE_LIBJPEG_TURBO
     tjDestroy(tjInstance);
+#endif
   }
   return result;
 }

CesiumGltfReader/src/decodeDraco.cpp

@@ -76,7 +76,7 @@ std::unique_ptr<draco::Mesh> decodeBufferViewToDracoMesh(
 
   const std::span<const std::byte> data(
       buffer.cesium.data.data() + bufferView.byteOffset,
-      static_cast<uint64_t>(bufferView.byteLength));
+      static_cast<size_t>(bufferView.byteLength));
 
   draco::DecoderBuffer decodeBuffer;
   decodeBuffer.Init(reinterpret_cast<const char*>(data.data()), data.size());

CesiumGltfReader/src/decodeSpz.cpp

@@ -0,0 +1,483 @@
+#include "decodeSpz.h"
+
+#include <CesiumGltf/Accessor.h>
+#include <CesiumGltf/Buffer.h>
+#include <CesiumGltf/BufferView.h>
+#include <CesiumGltf/ExtensionKhrGaussianSplatting.h>
+#include <CesiumGltf/ExtensionKhrGaussianSplattingCompressionSpz2.h>
+#include <CesiumGltf/Mesh.h>
+#include <CesiumGltf/MeshPrimitive.h>
+#include <CesiumGltf/Model.h>
+#include <CesiumGltfReader/GltfReader.h>
+#include <CesiumUtility/Assert.h>
+#include <CesiumUtility/JsonValue.h>
+#include <CesiumUtility/Tracing.h>
+
+#include <fmt/format.h>
+#include <glm/fwd.hpp>
+#include <load-spz.h>
+#include <splat-types.h>
+
+#include <cmath>
+#include <cstdint>
+#include <cstdlib>
+#include <cstring>
+#include <memory>
+#include <string>
+#include <unordered_map>
+#include <utility>
+#include <vector>
+
+namespace CesiumGltfReader {
+namespace {
+
+const float SH_C0 = 0.282095f;
+
+const std::string ALTERNATE_EXT_NAME1 = "KHR_spz_gaussian_splats_compression";
+const std::string ALTERNATE_EXT_NAME2 =
+    "KHR_gaussian_splatting_compression_spz";
+
+std::unique_ptr<spz::GaussianCloud> decodeBufferViewToGaussianCloud(
+    GltfReaderResult& readGltf,
+    CesiumGltf::MeshPrimitive& /* primitive */,
+    const CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2& spz) {
+  CESIUM_TRACE("CesiumGltfReader::decodeBufferViewToGaussianCloud");
+  CESIUM_ASSERT(readGltf.model);
+  CesiumGltf::Model& model = readGltf.model.value();
+
+  CesiumGltf::BufferView* pBufferView =
+      CesiumGltf::Model::getSafe(&model.bufferViews, spz.bufferView);
+  if (!pBufferView) {
+    readGltf.warnings.emplace_back("SPZ bufferView index is invalid.");
+    return nullptr;
+  }
+
+  const CesiumGltf::BufferView& bufferView = *pBufferView;
+
+  CesiumGltf::Buffer* pBuffer =
+      CesiumGltf::Model::getSafe(&model.buffers, bufferView.buffer);
+  if (!pBuffer) {
+    readGltf.warnings.emplace_back(
+        "SPZ bufferView has an invalid buffer index.");
+    return nullptr;
+  }
+
+  CesiumGltf::Buffer& buffer = *pBuffer;
+
+  if (bufferView.byteOffset < 0 || bufferView.byteLength < 0 ||
+      bufferView.byteOffset + bufferView.byteLength >
+          static_cast<int64_t>(buffer.cesium.data.size())) {
+    readGltf.warnings.emplace_back("SPZ bufferView extends beyond its buffer.");
+    return nullptr;
+  }
+
+  spz::GaussianCloud gaussians = spz::loadSpz(
+      reinterpret_cast<uint8_t*>(
+          buffer.cesium.data.data() + bufferView.byteOffset),
+      static_cast<int32_t>(bufferView.byteLength),
+      spz::UnpackOptions{spz::CoordinateSystem::UNSPECIFIED});
+
+  return std::make_unique<spz::GaussianCloud>(std::move(gaussians));
+}
+
+CesiumGltf::Accessor* findAccessor(
+    GltfReaderResult& readGltf,
+    CesiumGltf::MeshPrimitive& primitive,
+    const std::string& attributeName) {
+  const std::unordered_map<std::string, int32_t>::iterator attributeIt =
+      primitive.attributes.find(attributeName);
+  if (attributeIt == primitive.attributes.end()) {
+    readGltf.warnings.emplace_back(
+        "Failed to find " + attributeName +
+        " attribute on KHR_gaussian_splatting_compression_spz_2 primitive");
+    return nullptr;
+  }
+
+  CESIUM_ASSERT(readGltf.model);
+
+  CesiumGltf::Accessor* pAccessor = CesiumGltf::Model::getSafe(
+      &readGltf.model->accessors,
+      attributeIt->second);
+  if (!pAccessor) {
+    readGltf.warnings.emplace_back(
+        "Failed to find accessor at index " +
+        std::to_string(attributeIt->second));
+    return nullptr;
+  }
+
+  return pAccessor;
+}
+
+void copyShCoeff(
+    GltfReaderResult& readGltf,
+    CesiumGltf::MeshPrimitive& primitive,
+    CesiumGltf::Buffer& buffer,
+    spz::GaussianCloud* pGaussian,
+    int degree,
+    int coeffIndex) {
+  size_t base = 0;
+  size_t stride = 0;
+  if (degree == 1) {
+    stride = 9;
+  } else if (degree == 2) {
+    stride = 24;
+    base = 9;
+  } else if (degree == 3) {
+    stride = 45;
+    base = 24;
+  }
+
+  CesiumGltf::Accessor* pAccessor = findAccessor(
+      readGltf,
+      primitive,
+      fmt::format(
+          "KHR_gaussian_splatting:SH_DEGREE_{}_COEF_{}",
+          degree,
+          coeffIndex));
+  if (!pAccessor) {
+    return;
+  }
+
+  CESIUM_ASSERT(readGltf.model);
+
+  // Some gaussian splats seem to set this value as VEC4, even though the spec
+  // requires VEC3.
+  pAccessor->type = CesiumGltf::Accessor::Type::VEC3;
+
+  pAccessor->bufferView =
+      static_cast<int32_t>(readGltf.model->bufferViews.size());
+  CesiumGltf::BufferView& bufferView =
+      readGltf.model->bufferViews.emplace_back();
+  bufferView.buffer = static_cast<int32_t>(readGltf.model->buffers.size() - 1);
+  bufferView.byteLength = static_cast<int64_t>(
+      sizeof(float) * static_cast<size_t>(pGaussian->numPoints) * 3);
+
+  size_t start = buffer.cesium.data.size();
+  bufferView.byteOffset = static_cast<int64_t>(start);
+  buffer.cesium.data.resize(start + static_cast<size_t>(bufferView.byteLength));
+  for (size_t i = 0; i < static_cast<size_t>(pGaussian->numPoints); i++) {
+    const size_t idx = i * stride + base + static_cast<size_t>(coeffIndex) * 3;
+    std::memcpy(
+        buffer.cesium.data.data() + start,
+        pGaussian->sh.data() + idx,
+        sizeof(float) * 3);
+    start += sizeof(float) * 3;
+  }
+}
+
+void decodePrimitive(
+    GltfReaderResult& readGltf,
+    CesiumGltf::MeshPrimitive& primitive,
+    CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2& spz) {
+  CESIUM_TRACE("CesiumGltfReader::decodePrimitive");
+  CESIUM_ASSERT(readGltf.model);
+
+  // TODO: handle different accessor component types
+
+  std::unique_ptr<spz::GaussianCloud> pGaussian =
+      decodeBufferViewToGaussianCloud(readGltf, primitive, spz);
+  if (!pGaussian) {
+    return;
+  }
+
+  const size_t bufferLength =
+      sizeof(float) * (pGaussian->positions.size() + pGaussian->scales.size() +
+                       pGaussian->scales.size() + pGaussian->rotations.size() +
+                       pGaussian->alphas.size() + pGaussian->colors.size() +
+                       pGaussian->sh.size());
+
+  CesiumGltf::Buffer& buffer = readGltf.model->buffers.emplace_back();
+  buffer.byteLength = static_cast<int64_t>(bufferLength);
+  buffer.cesium.data.reserve(bufferLength);
+
+  // Position and rotation can be copied verbatim
+  CesiumGltf::Accessor* pPosAccessor =
+      findAccessor(readGltf, primitive, "POSITION");
+  if (pPosAccessor) {
+    pPosAccessor->type = CesiumGltf::Accessor::Type::VEC3;
+    pPosAccessor->bufferView =
+        static_cast<int32_t>(readGltf.model->bufferViews.size());
+    CesiumGltf::BufferView& bufferView =
+        readGltf.model->bufferViews.emplace_back();
+    bufferView.buffer =
+        static_cast<int32_t>(readGltf.model->buffers.size() - 1);
+    bufferView.byteLength =
+        static_cast<int64_t>(sizeof(float) * pGaussian->positions.size());
+
+    size_t start = buffer.cesium.data.size();
+    bufferView.byteOffset = static_cast<int64_t>(start);
+    buffer.cesium.data.resize(
+        start + static_cast<size_t>(bufferView.byteLength));
+    memcpy(
+        buffer.cesium.data.data() + start,
+        pGaussian->positions.data(),
+        sizeof(float) * pGaussian->positions.size());
+  }
+
+  CesiumGltf::Accessor* pRotAccessor =
+      findAccessor(readGltf, primitive, "KHR_gaussian_splatting:ROTATION");
+  if (pRotAccessor) {
+    pRotAccessor->type = CesiumGltf::Accessor::Type::VEC4;
+    pRotAccessor->bufferView =
+        static_cast<int32_t>(readGltf.model->bufferViews.size());
+    CesiumGltf::BufferView& bufferView =
+        readGltf.model->bufferViews.emplace_back();
+    bufferView.buffer =
+        static_cast<int32_t>(readGltf.model->buffers.size() - 1);
+    bufferView.byteLength =
+        static_cast<int64_t>(sizeof(float) * pGaussian->rotations.size());
+
+    size_t start = buffer.cesium.data.size();
+    bufferView.byteOffset = static_cast<int64_t>(start);
+    buffer.cesium.data.resize(
+        start + static_cast<size_t>(bufferView.byteLength));
+    memcpy(
+        buffer.cesium.data.data() + start,
+        pGaussian->rotations.data(),
+        sizeof(float) * pGaussian->rotations.size());
+  }
+
+  // Color needs to be interleaved with alphas and have its values converted
+  CesiumGltf::Accessor* pColorAccessor =
+      findAccessor(readGltf, primitive, "COLOR_0");
+  if (pColorAccessor) {
+    pColorAccessor->type = CesiumGltf::Accessor::Type::VEC4;
+    pColorAccessor->componentType = CesiumGltf::Accessor::ComponentType::FLOAT;
+    pColorAccessor->bufferView =
+        static_cast<int32_t>(readGltf.model->bufferViews.size());
+    CesiumGltf::BufferView& bufferView =
+        readGltf.model->bufferViews.emplace_back();
+    bufferView.buffer =
+        static_cast<int32_t>(readGltf.model->buffers.size() - 1);
+    bufferView.byteLength = static_cast<int64_t>(
+        (pGaussian->colors.size() + pGaussian->alphas.size()) * sizeof(float));
+
+    size_t start = buffer.cesium.data.size();
+    buffer.cesium.data.resize(
+        start + static_cast<size_t>(bufferView.byteLength));
+    bufferView.byteOffset = static_cast<int64_t>(start);
+    for (size_t i = 0; i < pGaussian->alphas.size(); i++) {
+      glm::fvec4 color(
+          0.5 + pGaussian->colors[i * 3] * SH_C0,
+          0.5 + pGaussian->colors[i * 3 + 1] * SH_C0,
+          0.5 + pGaussian->colors[i * 3 + 2] * SH_C0,
+          1.0 / (1.0 + exp(-pGaussian->alphas[i])));
+      memcpy(
+          buffer.cesium.data.data() + start + i * sizeof(glm::fvec4),
+          &color,
+          sizeof(glm::fvec4));
+    }
+  }
+
+  // Scale needs to be converted
+  CesiumGltf::Accessor* pScaleAccessor =
+      findAccessor(readGltf, primitive, "KHR_gaussian_splatting:SCALE");
+  if (pScaleAccessor) {
+    pScaleAccessor->type = CesiumGltf::Accessor::Type::VEC3;
+    pScaleAccessor->bufferView =
+        static_cast<int32_t>(readGltf.model->bufferViews.size());
+    CesiumGltf::BufferView& bufferView =
+        readGltf.model->bufferViews.emplace_back();
+    bufferView.buffer =
+        static_cast<int32_t>(readGltf.model->buffers.size() - 1);
+    bufferView.byteLength =
+        static_cast<int64_t>(sizeof(float) * pGaussian->scales.size());
+
+    size_t start = buffer.cesium.data.size();
+    buffer.cesium.data.resize(
+        start + static_cast<size_t>(bufferView.byteLength));
+    bufferView.byteOffset = static_cast<int64_t>(start);
+    for (size_t i = 0; i < pGaussian->scales.size(); i++) {
+      float scale = exp(pGaussian->scales[i]);
+      memcpy(
+          buffer.cesium.data.data() + start + i * sizeof(float),
+          &scale,
+          sizeof(float));
+    }
+  }
+
+  if (pGaussian->shDegree > 0) {
+    for (int i = 0; i < 3; i++) {
+      copyShCoeff(readGltf, primitive, buffer, pGaussian.get(), 1, i);
+    }
+  }
+
+  if (pGaussian->shDegree > 1) {
+    for (int i = 0; i < 5; i++) {
+      copyShCoeff(readGltf, primitive, buffer, pGaussian.get(), 2, i);
+    }
+  }
+
+  if (pGaussian->shDegree > 2) {
+    for (int i = 0; i < 7; i++) {
+      copyShCoeff(readGltf, primitive, buffer, pGaussian.get(), 3, i);
+    }
+  }
+}
+
+CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2*
+addExtensionFromJsonValue(
+    const std::string& extName,
+    CesiumGltfReader::GltfReaderResult& readGltf,
+    CesiumGltf::ExtensionKhrGaussianSplatting& splatting,
+    CesiumUtility::JsonValue* pKhrJson) {
+  if (!pKhrJson->isObject()) {
+    readGltf.errors.push_back(fmt::format("Invalid {} extension", extName));
+    return nullptr;
+  }
+
+  const CesiumUtility::JsonValue::Object::const_iterator it =
+      pKhrJson->getObject().find("bufferView");
+  if (it == pKhrJson->getObject().end()) {
+    readGltf.errors.push_back(
+        fmt::format("No `bufferView` property found on {} extension", extName));
+    return nullptr;
+  }
+
+  if (!it->second.isInt64() && !it->second.isUint64()) {
+    readGltf.errors.push_back(fmt::format(
+        "`bufferView` property on {} extension must be an integer value",
+        extName));
+    return nullptr;
+  }
+
+  CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2& ext =
+      splatting.addExtension<
+          CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2>();
+  ext.bufferView = it->second.isInt64()
+                       ? static_cast<int32_t>(it->second.getInt64())
+                       : static_cast<int32_t>(it->second.getUint64());
+  return &ext;
+}
+
+// Maps attribute names from older versions of the extension to the names from
+// the current version of the extension.
+void fixAttributeNames(CesiumGltf::MeshPrimitive& primitive) {
+  std::vector<std::string> attributesToConvert;
+  attributesToConvert.reserve(primitive.attributes.size());
+  for (std::pair<const std::string, int32_t>& attribute :
+       primitive.attributes) {
+    if (attribute.first == "_SCALE" || attribute.first == "_ROTATION" ||
+        attribute.first.starts_with("_SH_DEGREE_")) {
+      attributesToConvert.push_back(attribute.first);
+    }
+  }
+
+  for (const std::string& oldName : attributesToConvert) {
+    const int32_t accessorIndex = primitive.attributes[oldName];
+    primitive.attributes.erase(oldName);
+    primitive.attributes.emplace(
+        "KHR_gaussian_splatting:" + oldName.substr(1),
+        accessorIndex);
+  }
+}
+
+CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2*
+getAndMaybeConvertSpzExtension(
+    CesiumGltfReader::GltfReaderResult& readGltf,
+    CesiumGltf::MeshPrimitive& primitive,
+    CesiumGltf::ExtensionKhrGaussianSplatting& splatting) {
+
+  // Check for the real thing.
+  CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2* pSpz =
+      splatting.getExtension<
+          CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2>();
+  if (pSpz) {
+    return pSpz;
+  }
+
+  // Check for the old versions.
+  CesiumUtility::JsonValue* pKhrSpz =
+      primitive.getGenericExtension(ALTERNATE_EXT_NAME1);
+  if (pKhrSpz != nullptr) {
+    CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2* pResult =
+        addExtensionFromJsonValue(
+            ALTERNATE_EXT_NAME1,
+            readGltf,
+            splatting,
+            pKhrSpz);
+    primitive.extensions.erase(ALTERNATE_EXT_NAME1);
+    return pResult;
+  }
+
+  CesiumUtility::JsonValue* pSpzNoVersion =
+      splatting.getGenericExtension(ALTERNATE_EXT_NAME2);
+  if (pSpzNoVersion != nullptr) {
+    CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2* pResult =
+        addExtensionFromJsonValue(
+            ALTERNATE_EXT_NAME2,
+            readGltf,
+            splatting,
+            pSpzNoVersion);
+    primitive.extensions.erase(ALTERNATE_EXT_NAME2);
+    return pResult;
+  }
+
+  return nullptr;
+}
+} // namespace
+
+void decodeSpz(CesiumGltfReader::GltfReaderResult& readGltf) {
+  CESIUM_TRACE("CesiumGltfReader::decodeSpz");
+  if (!readGltf.model) {
+    return;
+  }
+
+  CesiumGltf::Model& model = readGltf.model.value();
+
+  for (CesiumGltf::Mesh& mesh : model.meshes) {
+    for (CesiumGltf::MeshPrimitive& primitive : mesh.primitives) {
+      // KHR_spz_gaussian_splats_compression has no KHR_gaussian_splatting
+      // extension attached Just throw one on there to make this easier
+      if (primitive.extensions.contains(ALTERNATE_EXT_NAME1)) {
+        primitive.addExtension<CesiumGltf::ExtensionKhrGaussianSplatting>();
+      }
+
+      CesiumGltf::ExtensionKhrGaussianSplatting* pSplat =
+          primitive.getExtension<CesiumGltf::ExtensionKhrGaussianSplatting>();
+      if (!pSplat) {
+        continue;
+      }
+
+      CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2* pSpz =
+          getAndMaybeConvertSpzExtension(readGltf, primitive, *pSplat);
+      if (!pSpz) {
+        continue;
+      }
+
+      fixAttributeNames(primitive);
+      decodePrimitive(readGltf, primitive, *pSpz);
+
+      // Remove the SPZ extension as it no longer applies.
+      pSplat->extensions.erase(
+          CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2::
+              ExtensionName);
+    }
+  }
+
+  model.removeExtensionRequired(
+      CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2::ExtensionName);
+  model.removeExtensionRequired(ALTERNATE_EXT_NAME1);
+  model.removeExtensionRequired(ALTERNATE_EXT_NAME2);
+}
+
+bool hasSpzExtension(GltfReaderResult& readGltf) {
+  CESIUM_ASSERT(readGltf.model);
+
+  if (readGltf.model->isExtensionUsed(
+          CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2::
+              ExtensionName)) {
+    return true;
+  }
+
+  if (readGltf.model->isExtensionUsed(ALTERNATE_EXT_NAME1)) {
+    return true;
+  }
+
+  if (readGltf.model->isExtensionUsed(ALTERNATE_EXT_NAME2)) {
+    return true;
+  }
+
+  return false;
+}
+} // namespace CesiumGltfReader

CesiumGltfReader/src/decodeSpz.h

@@ -0,0 +1,8 @@
+#pragma once
+
+namespace CesiumGltfReader {
+struct GltfReaderResult;
+
+void decodeSpz(GltfReaderResult& readGltf);
+bool hasSpzExtension(GltfReaderResult& readGltf);
+} // namespace CesiumGltfReader

CesiumGltfReader/test/TestGltfReader.cpp

@@ -813,3 +813,54 @@ TEST_CASE("GltfReader::postprocessGltf") {
     CHECK(s == "test");
   }
 }
+
+TEST_CASE("SPZ decoding works properly") {
+  SUBCASE("Basic model with one vertex no spherical harmonics") {
+    GltfReader reader;
+    GltfReaderResult result = reader.readGltf(readFile(
+        std::filesystem::path(CesiumGltfReader_TEST_DATA_DIR) / "SpzSplat" /
+        "basic.glb"));
+    REQUIRE(result.model);
+    const Model& model = result.model.value();
+
+    REQUIRE(model.meshes.size() == 1);
+    REQUIRE(model.meshes[0].primitives.size() == 1);
+
+    const std::unordered_map<std::string, int32_t>& attributes =
+        model.meshes[0].primitives[0].attributes;
+
+    CHECK(attributes.size() == 4);
+
+    REQUIRE(attributes.contains("POSITION"));
+    AccessorView<glm::vec3> positionView(model, attributes.at("POSITION"));
+    REQUIRE(positionView.status() == AccessorViewStatus::Valid);
+    REQUIRE(positionView.size() == 1);
+    CHECK(positionView[0] == glm::vec3(1.0, 2.0, 3.0));
+
+    REQUIRE(attributes.contains("COLOR_0"));
+    AccessorView<glm::vec4> colorView(model, attributes.at("COLOR_0"));
+    REQUIRE(colorView.status() == AccessorViewStatus::Valid);
+    REQUIRE(colorView.size() == 1);
+    CHECK(
+        colorView[0] ==
+        glm::vec4(0.570062876, 0.643813193, 0.710188448, 0.501960814));
+
+    REQUIRE(attributes.contains("KHR_gaussian_splatting:ROTATION"));
+    AccessorView<glm::vec4> rotationView(
+        model,
+        attributes.at("KHR_gaussian_splatting:ROTATION"));
+    REQUIRE(rotationView.status() == AccessorViewStatus::Valid);
+    REQUIRE(rotationView.size() == 1);
+    CHECK(
+        rotationView[0] ==
+        glm::vec4(0.003921628, -0.709803939, 0.709804058, 0.0));
+
+    REQUIRE(attributes.contains("KHR_gaussian_splatting:SCALE"));
+    AccessorView<glm::vec3> scaleView(
+        model,
+        attributes.at("KHR_gaussian_splatting:SCALE"));
+    REQUIRE(scaleView.status() == AccessorViewStatus::Valid);
+    REQUIRE(scaleView.size() == 1);
+    CHECK(scaleView[0] == glm::vec3(20.085537, 7.38905621, 2.71828175));
+  }
+}

CesiumGltfWriter/generated/src/ModelJsonWriter.cpp

@@ -38,6 +38,8 @@
 #include <CesiumGltf/ExtensionExtPrimitiveVoxels.h>
 #include <CesiumGltf/ExtensionExtStructuralMetadata.h>
 #include <CesiumGltf/ExtensionKhrDracoMeshCompression.h>
+#include <CesiumGltf/ExtensionKhrGaussianSplatting.h>
+#include <CesiumGltf/ExtensionKhrGaussianSplattingCompressionSpz2.h>
 #include <CesiumGltf/ExtensionKhrImplicitShapes.h>
 #include <CesiumGltf/ExtensionKhrMaterialsUnlit.h>
 #include <CesiumGltf/ExtensionKhrTextureBasisu.h>
@@ -218,6 +220,16 @@ void writeJson(
     CesiumJsonWriter::JsonWriter& jsonWriter,
     const CesiumJsonWriter::ExtensionWriterContext& context);
 
+void writeJson(
+    const CesiumGltf::ExtensionKhrGaussianSplatting& obj,
+    CesiumJsonWriter::JsonWriter& jsonWriter,
+    const CesiumJsonWriter::ExtensionWriterContext& context);
+
+void writeJson(
+    const CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2& obj,
+    CesiumJsonWriter::JsonWriter& jsonWriter,
+    const CesiumJsonWriter::ExtensionWriterContext& context);
+
 void writeJson(
     const CesiumGltf::Padding& obj,
     CesiumJsonWriter::JsonWriter& jsonWriter,
@@ -1174,6 +1186,56 @@ void writeJson(
   jsonWriter.EndObject();
 }
 
+void writeJson(
+    const CesiumGltf::ExtensionKhrGaussianSplatting& obj,
+    CesiumJsonWriter::JsonWriter& jsonWriter,
+    const CesiumJsonWriter::ExtensionWriterContext& context) {
+  jsonWriter.StartObject();
+
+  if (obj.kernel != "ellipse") {
+    jsonWriter.Key("kernel");
+    writeJson(obj.kernel, jsonWriter, context);
+  }
+
+  if (obj.projection !=
+      CesiumGltf::ExtensionKhrGaussianSplatting::Projection::perspective) {
+    jsonWriter.Key("projection");
+    writeJson(obj.projection, jsonWriter, context);
+  }
+
+  if (obj.sortingMethod != CesiumGltf::ExtensionKhrGaussianSplatting::
+                               SortingMethod::cameraDistance) {
+    jsonWriter.Key("sortingMethod");
+    writeJson(obj.sortingMethod, jsonWriter, context);
+  }
+
+  if (obj.colorSpace !=
+      CesiumGltf::ExtensionKhrGaussianSplatting::ColorSpace::BT_709) {
+    jsonWriter.Key("colorSpace");
+    writeJson(obj.colorSpace, jsonWriter, context);
+  }
+
+  writeExtensibleObject(obj, jsonWriter, context);
+
+  jsonWriter.EndObject();
+}
+
+void writeJson(
+    const CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2& obj,
+    CesiumJsonWriter::JsonWriter& jsonWriter,
+    const CesiumJsonWriter::ExtensionWriterContext& context) {
+  jsonWriter.StartObject();
+
+  if (obj.bufferView > -1) {
+    jsonWriter.Key("bufferView");
+    writeJson(obj.bufferView, jsonWriter, context);
+  }
+
+  writeExtensibleObject(obj, jsonWriter, context);
+
+  jsonWriter.EndObject();
+}
+
 void writeJson(
     const CesiumGltf::Padding& obj,
     CesiumJsonWriter::JsonWriter& jsonWriter,
@@ -2892,6 +2954,20 @@ void ExtensionExtPrimitiveVoxelsJsonWriter::write(
   writeJson(obj, jsonWriter, context);
 }
 
+void ExtensionKhrGaussianSplattingJsonWriter::write(
+    const CesiumGltf::ExtensionKhrGaussianSplatting& obj,
+    CesiumJsonWriter::JsonWriter& jsonWriter,
+    const CesiumJsonWriter::ExtensionWriterContext& context) {
+  writeJson(obj, jsonWriter, context);
+}
+
+void ExtensionKhrGaussianSplattingCompressionSpz2JsonWriter::write(
+    const CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2& obj,
+    CesiumJsonWriter::JsonWriter& jsonWriter,
+    const CesiumJsonWriter::ExtensionWriterContext& context) {
+  writeJson(obj, jsonWriter, context);
+}
+
 void PaddingJsonWriter::write(
     const CesiumGltf::Padding& obj,
     CesiumJsonWriter::JsonWriter& jsonWriter,

CesiumGltfWriter/generated/src/ModelJsonWriter.h

@@ -34,6 +34,8 @@ struct ExtensionKhrImplicitShapes;
 struct ExtensionExtImplicitEllipsoidRegion;
 struct ExtensionExtImplicitCylinderRegion;
 struct ExtensionExtPrimitiveVoxels;
+struct ExtensionKhrGaussianSplatting;
+struct ExtensionKhrGaussianSplattingCompressionSpz2;
 struct Padding;
 struct Shape;
 struct Cylinder;
@@ -402,6 +404,33 @@ struct ExtensionExtPrimitiveVoxelsJsonWriter {
       const CesiumJsonWriter::ExtensionWriterContext& context);
 };
 
+struct ExtensionKhrGaussianSplattingJsonWriter {
+  using ValueType = CesiumGltf::ExtensionKhrGaussianSplatting;
+
+  /** @brief The official name of the extension. This should be the same as its
+   * key in the `extensions` object. */
+  static constexpr const char* ExtensionName = "KHR_gaussian_splatting";
+
+  static void write(
+      const CesiumGltf::ExtensionKhrGaussianSplatting& obj,
+      CesiumJsonWriter::JsonWriter& jsonWriter,
+      const CesiumJsonWriter::ExtensionWriterContext& context);
+};
+
+struct ExtensionKhrGaussianSplattingCompressionSpz2JsonWriter {
+  using ValueType = CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2;
+
+  /** @brief The official name of the extension. This should be the same as its
+   * key in the `extensions` object. */
+  static constexpr const char* ExtensionName =
+      "KHR_gaussian_splatting_compression_spz_2";
+
+  static void write(
+      const CesiumGltf::ExtensionKhrGaussianSplattingCompressionSpz2& obj,
+      CesiumJsonWriter::JsonWriter& jsonWriter,
+      const CesiumJsonWriter::ExtensionWriterContext& context);
+};
+
 struct PaddingJsonWriter {
   using ValueType = CesiumGltf::Padding;
 

CesiumGltfWriter/generated/src/registerWriterExtensions.cpp

@@ -7,6 +7,7 @@
 
 #include <CesiumGltf/Buffer.h>
 #include <CesiumGltf/BufferView.h>
+#include <CesiumGltf/ExtensionKhrGaussianSplatting.h>
 #include <CesiumGltf/FeatureIdTexture.h>
 #include <CesiumGltf/Material.h>
 #include <CesiumGltf/MaterialNormalTextureInfo.h>
@@ -34,6 +35,8 @@
 #include <CesiumGltf/ExtensionExtPrimitiveVoxels.h>
 #include <CesiumGltf/ExtensionExtStructuralMetadata.h>
 #include <CesiumGltf/ExtensionKhrDracoMeshCompression.h>
+#include <CesiumGltf/ExtensionKhrGaussianSplatting.h>
+#include <CesiumGltf/ExtensionKhrGaussianSplattingCompressionSpz2.h>
 #include <CesiumGltf/ExtensionKhrImplicitShapes.h>
 #include <CesiumGltf/ExtensionKhrMaterialsUnlit.h>
 #include <CesiumGltf/ExtensionKhrTextureBasisu.h>
@@ -86,6 +89,9 @@ void registerWriterExtensions(
   context.registerExtension<
       CesiumGltf::MeshPrimitive,
       ExtensionExtPrimitiveVoxelsJsonWriter>();
+  context.registerExtension<
+      CesiumGltf::MeshPrimitive,
+      ExtensionKhrGaussianSplattingJsonWriter>();
   context.registerExtension<
       CesiumGltf::Node,
       ExtensionExtInstanceFeaturesJsonWriter>();
@@ -136,5 +142,8 @@ void registerWriterExtensions(
   context.registerExtension<
       CesiumGltf::Shape,
       ExtensionExtImplicitCylinderRegionJsonWriter>();
+  context.registerExtension<
+      CesiumGltf::ExtensionKhrGaussianSplatting,
+      ExtensionKhrGaussianSplattingCompressionSpz2JsonWriter>();
 }
 } // namespace CesiumGltfWriter

CesiumGltfWriter/test/TestGltfWriter.cpp

@@ -613,6 +613,7 @@ TEST_CASE("Writes glb with binaryChunkByteAlignment of 8") {
   REQUIRE(glbBytesExtraPadding.size() == 88);
 }
 
+#ifndef __EMSCRIPTEN__
 TEST_CASE("Reports an error if asked to write a GLB larger than 4GB") {
   CesiumGltf::Model model;
   model.asset.version = "2.0";
@@ -628,3 +629,4 @@ TEST_CASE("Reports an error if asked to write a GLB larger than 4GB") {
   REQUIRE(!result.errors.empty());
   CHECK(result.gltfBytes.empty());
 }
+#endif // __EMSCRIPTEN__

CesiumITwinClient/test/TestConnection.cpp

@@ -23,7 +23,7 @@ using namespace CesiumNativeTests;
 using namespace CesiumUtility;
 
 namespace {
-const std::string& REDIRECT_PATH = "/dummy/auth/path";
+const std::string REDIRECT_PATH = "/dummy/auth/path";
 const int REDIRECT_PORT = 49013;
 
 std::shared_ptr<Connection>
@@ -169,4 +169,4 @@ TEST_CASE("CesiumITwinClient::Connection::geospatialFeatureCollections") {
         collection.storageCrs ==
         "https://www.opengis.net/def/crs/EPSG/0/32615");
   }
-}
+}

CesiumNativeTests/CMakeLists.txt

@@ -38,6 +38,14 @@ cesium_glob_files(test_headers
 )
 set(test_include_directories ${CMAKE_CURRENT_LIST_DIR}/include)
 
+if(CESIUM_TARGET_WASM)
+    target_link_options(
+        cesium-native-tests
+        PRIVATE
+        "-sEXIT_RUNTIME=1" 
+    )
+endif()
+
 # Iterate through all targets, extracting their private sources and test sources / test headers
 foreach(target ${cesium_native_targets})
     get_target_property(target_test_sources ${target} TEST_SOURCES)
@@ -75,6 +83,41 @@ foreach(target ${cesium_native_targets})
     endif()
 endforeach()
 
+if(CESIUM_TARGET_WASM)
+  file(GLOB directories_list LIST_DIRECTORIES true "${CMAKE_SOURCE_DIR}/Cesium*")
+  set(FILE_PACKAGER_ARGS "")
+  set(TEST_DATA_FILES "")
+  foreach(dir ${directories_list})
+    if(IS_DIRECTORY ${dir}/test/data)
+      list(APPEND FILE_PACKAGER_ARGS "--embed" "${dir}/test/data")
+
+      file(GLOB_RECURSE data_files "${dir}/test/data/*")
+      list(APPEND TEST_DATA_FILES ${data_files})
+    endif()
+  endforeach()
+
+  list(APPEND FILE_PACKAGER_ARGS "--embed" "${CMAKE_SOURCE_DIR}/data")
+
+  if(CESIUM_WASM64)
+    list(APPEND FILE_PACKAGER_ARGS "--wasm64")
+  endif()
+
+  set(CESIUM_NATIVE_TESTS_DATA_OBJ ${CMAKE_CURRENT_BINARY_DIR}/cesium-native-tests-data.o)
+  add_custom_command(
+    COMMENT "Generating test data object file"
+    OUTPUT ${CESIUM_NATIVE_TESTS_DATA_OBJ}
+    COMMAND ${EMSCRIPTEN_ROOT_PATH}/tools/file_packager none.data ${FILE_PACKAGER_ARGS} --obj-output=${CESIUM_NATIVE_TESTS_DATA_OBJ}
+    VERBATIM
+    DEPENDS ${TEST_DATA_FILES}
+  )
+
+  target_sources(
+    cesium-native-tests
+    PRIVATE
+      ${CESIUM_NATIVE_TESTS_DATA_OBJ}
+  )
+endif()
+
 target_sources(
     cesium-native-tests
     PRIVATE
@@ -99,9 +142,12 @@ PRIVATE
 
 target_compile_definitions(cesium-native-tests
 PRIVATE
-  CESIUM_NATIVE_DATA_DIR=\"${CMAKE_CURRENT_LIST_DIR}/../data\"
+  CESIUM_NATIVE_DATA_DIR=\"${CMAKE_SOURCE_DIR}/data\"
 )
 
 include(CTest)
 include(doctest)
-doctest_discover_tests(cesium-native-tests)
+if(NOT CESIUM_TARGET_WASM)
+    # doctest_discover_tests can't handle the target being an html file, so we just avoid it on a wasm build
+    doctest_discover_tests(cesium-native-tests)
+endif()

CesiumNativeTests/src/FileAccessor.cpp

@@ -43,10 +43,10 @@ std::unique_ptr<SimpleAssetResponse> readFileUri(const std::string& uri) {
   if (!file) {
     return response(404);
   }
-  std::streamsize size = file.tellg();
+  std::streamoff size = file.tellg();
   file.seekg(0, std::ios::beg);
-  result.resize(static_cast<size_t>(size));
-  file.read(reinterpret_cast<char*>(result.data()), size);
+  result.resize(size_t(size));
+  file.read(reinterpret_cast<char*>(result.data()), std::streamsize(size));
   if (!file) {
     return response(503);
   } else {

CesiumNativeTests/src/readFile.cpp

@@ -12,11 +12,11 @@ std::vector<std::byte> readFile(const std::filesystem::path& fileName) {
   std::ifstream file(fileName, std::ios::binary | std::ios::ate);
   REQUIRE(file);
 
-  std::streamsize size = file.tellg();
+  std::streamoff size = file.tellg();
   file.seekg(0, std::ios::beg);
 
-  std::vector<std::byte> buffer(static_cast<size_t>(size));
-  file.read(reinterpret_cast<char*>(buffer.data()), size);
+  std::vector<std::byte> buffer{size_t(size)};
+  file.read(reinterpret_cast<char*>(buffer.data()), std::streamsize(size));
 
   return buffer;
 }

CesiumQuantizedMeshTerrain/src/QuantizedMeshLoader.cpp

@@ -506,7 +506,7 @@ void addSkirts(
       westEdgeIndices.begin(),
       westEdgeIndices.end(),
       sortEdgeIndices.begin(),
-      sortEdgeIndices.begin() + westVertexCount,
+      sortEdgeIndices.begin() + ptrdiff_t(westVertexCount),
       [&uvsAndHeights](auto lhs, auto rhs) noexcept {
         return uvsAndHeights[lhs].y < uvsAndHeights[rhs].y;
       });
@@ -539,7 +539,7 @@ void addSkirts(
       southEdgeIndices.begin(),
       southEdgeIndices.end(),
       sortEdgeIndices.begin(),
-      sortEdgeIndices.begin() + southVertexCount,
+      sortEdgeIndices.begin() + ptrdiff_t(southVertexCount),
       [&uvsAndHeights](auto lhs, auto rhs) noexcept {
         return uvsAndHeights[lhs].x > uvsAndHeights[rhs].x;
       });
@@ -572,7 +572,7 @@ void addSkirts(
       eastEdgeIndices.begin(),
       eastEdgeIndices.end(),
       sortEdgeIndices.begin(),
-      sortEdgeIndices.begin() + eastVertexCount,
+      sortEdgeIndices.begin() + ptrdiff_t(eastVertexCount),
       [&uvsAndHeights](auto lhs, auto rhs) noexcept {
         return uvsAndHeights[lhs].y > uvsAndHeights[rhs].y;
       });
@@ -605,7 +605,7 @@ void addSkirts(
       northEdgeIndices.begin(),
       northEdgeIndices.end(),
       sortEdgeIndices.begin(),
-      sortEdgeIndices.begin() + northVertexCount,
+      sortEdgeIndices.begin() + ptrdiff_t(northVertexCount),
       [&uvsAndHeights](auto lhs, auto rhs) noexcept {
         return uvsAndHeights[lhs].x < uvsAndHeights[rhs].x;
       });
@@ -754,11 +754,10 @@ QuantizedMeshMetadataResult processMetadata(
   // decode position without skirt, but preallocate position buffer to include
   // skirt as well
   std::vector<std::byte> outputPositionsBuffer(
-      static_cast<uint64_t>((vertexCount + skirtVertexCount) * 3) *
-      sizeof(float));
+      size_t((vertexCount + skirtVertexCount) * 3) * sizeof(float));
   std::span<float> outputPositions(
       reinterpret_cast<float*>(outputPositionsBuffer.data()),
-      static_cast<size_t>((vertexCount + skirtVertexCount) * 3));
+      size_t((vertexCount + skirtVertexCount) * 3));
   size_t positionOutputIndex = 0;
 
   const glm::dvec3 center(

CesiumRasterOverlays/CMakeLists.txt

@@ -51,6 +51,7 @@ target_link_libraries(CesiumRasterOverlays
         CesiumUtility
         CesiumVectorData
         nonstd::expected-lite
+        spdlog::spdlog
     PRIVATE
         tinyxml2::tinyxml2
 )

CesiumRasterOverlays/src/RasterOverlayUtilities.cpp

@@ -591,7 +591,7 @@ RasterOverlayUtilities::upsampleGltfForRasterOverlays(
       // We're assuming here that nothing references primitives by index, so we
       // can remove them without any drama.
       if (!keep) {
-        mesh.primitives.erase(mesh.primitives.begin() + int64_t(i));
+        mesh.primitives.erase(mesh.primitives.begin() + ptrdiff_t(i));
         --i;
       }
       containsPrimitives |= !mesh.primitives.empty();

CesiumUtility/include/CesiumUtility/Hash.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <cstddef>
+#include <cstdint>
 
 namespace CesiumUtility {
 
@@ -17,7 +18,7 @@ struct Hash {
    * @param second The second hash value.
    * @return A new hash value which is a combination of the two.
    */
-  static std::size_t combine(std::size_t first, std::size_t second);
+  static size_t combine(size_t first, size_t second);
 };
 
 } // namespace CesiumUtility

CesiumUtility/src/Hash.cpp

@@ -1,6 +1,8 @@
 #include <CesiumUtility/Hash.h>
 
+#include <climits>
 #include <cstddef>
+#include <cstdint>
 
 namespace CesiumUtility {
 
@@ -59,23 +61,50 @@ namespace CesiumUtility {
 // (https://mostlymangling.blogspot.com/2019/12/stronger-better-morer-moremur-better.html)
 namespace {
 
-inline std::size_t mix(std::size_t x) {
-  std::size_t const m = 0xe9846af9b1a615d;
+template <size_t Bits> struct hash_mix_impl;
 
-  x ^= x >> 32;
-  x *= m;
-  x ^= x >> 32;
-  x *= m;
-  x ^= x >> 28;
+template <> struct hash_mix_impl<64> {
+  inline static uint64_t fn(uint64_t x) {
+    uint64_t const m = 0xe9846af9b1a615d;
 
-  return x;
-}
+    x ^= x >> 32;
+    x *= m;
+    x ^= x >> 32;
+    x *= m;
+    x ^= x >> 28;
+
+    return x;
+  }
+};
+
+// This function is adapted from Boost v1.86.0, `hash_mix_impl<32>` function.
+//
+// hash_mix for 32 bit size_t
+//
+// We use the "best xmxmx" implementation from
+// https://github.com/skeeto/hash-prospector/issues/19
+template <> struct hash_mix_impl<32> {
+  inline static uint32_t fn(uint32_t x) {
+    uint32_t const m1 = 0x21f0aaad;
+    uint32_t const m2 = 0x735a2d97;
+
+    x ^= x >> 16;
+    x *= m1;
+    x ^= x >> 15;
+    x *= m2;
+    x ^= x >> 15;
+
+    return x;
+  }
+};
 
 } // namespace
 
 // This function is adapted from Boost's `hash_combine`.
-std::size_t Hash::combine(std::size_t first, std::size_t second) {
-  return mix(first + 0x9e3779b9 + second);
+size_t Hash::combine(size_t first, size_t second) {
+  // This will truncate bits on 32-bit builds.
+  return hash_mix_impl<sizeof(size_t) * CHAR_BIT>::fn(
+      first + size_t(0x9e3779b9) + second);
 }
 
 } // namespace CesiumUtility

CesiumVectorData/CMakeLists.txt

@@ -44,7 +44,7 @@ cesium_target_include_directories(
         ${CMAKE_CURRENT_LIST_DIR}/src
 )
 
-if(NOT IOS AND NOT VCPKG_CMAKE_SYSTEM_NAME MATCHES "iOS")
+if(NOT CESIUM_TARGET_WASM AND NOT IOS AND NOT VCPKG_CMAKE_SYSTEM_NAME MATCHES "iOS")
     set(CESIUM_VECTOR_DATA_ASMJIT_DEPENDENCY asmjit::asmjit)
 endif()
 

CesiumVectorData/src/VectorRasterizer.cpp

@@ -94,7 +94,7 @@ VectorRasterizer::VectorRasterizer(
       imageHeight,
       BL_FORMAT_PRGB32,
       reinterpret_cast<void*>(pData),
-      (int64_t)imageWidth * (int64_t)this->_imageAsset->channels);
+      intptr_t(imageWidth) * intptr_t(this->_imageAsset->channels));
 
   this->_context.begin(this->_image);
   // Initialize the image as all transparent.

cmake/compiler.cmake

@@ -3,3 +3,14 @@
 # else()
 #     add_compile_options(-Werror -Wall -Wextra -Wconversion -Wpedantic -Wshadow -Wsign-conversion)
 # endif()
+
+if(CESIUM_TARGET_WASM)
+  add_compile_options(-pthread -msimd128 -mnontrapping-fptoint -mbulk-memory -fwasm-exceptions -sSUPPORT_LONGJMP=wasm)
+  add_link_options(-pthread -sALLOW_MEMORY_GROWTH=1 -sPTHREAD_POOL_SIZE=4 -sMAXIMUM_MEMORY=4294967296 -sMIN_NODE_VERSION=200000 -sINITIAL_MEMORY=268435456 -sSTACK_SIZE=1048576 -fwasm-exceptions -mbulk-memory -mnontrapping-fptoint -msse4.2 -sWASM_BIGINT -sSUPPORT_LONGJMP=wasm -sFORCE_FILESYSTEM -sPROXY_TO_PTHREAD)
+  add_link_options($<$<CONFIG:Debug>:-gsource-map>)
+
+  if (CESIUM_WASM64)
+    add_compile_options(-sMEMORY64=1)
+    add_link_options(-sMEMORY64=1)
+  endif()
+endif()

cmake/config/Config.cmake.in

@@ -21,6 +21,7 @@ find_dependency(meshoptimizer CONFIG REQUIRED)
 find_dependency(OpenSSL REQUIRED)
 find_dependency(s2 CONFIG REQUIRED)
 find_dependency(spdlog CONFIG REQUIRED)
+find_dependency(spz CONFIG REQUIRED)
 find_dependency(tinyxml2 CONFIG REQUIRED)
 find_dependency(unofficial-sqlite3 CONFIG REQUIRED)
 find_dependency(WebP CONFIG REQUIRED)

cmake/detect-vcpkg-triplet.cmake

@@ -1,4 +1,6 @@
-if(ANDROID)
+if(CESIUM_TARGET_WASM)
+    set(DETECTED_VCPKG_TRIPLET "wasm32-emscripten")
+elseif(ANDROID)
     if(CMAKE_SYSTEM_PROCESSOR STREQUAL "x86_64")
         set(DETECTED_VCPKG_TRIPLET "x64-android")
     else()

cmake/ezvcpkg/ezvcpkg.cmake

@@ -161,7 +161,7 @@ macro(EZVCPKG_BOOTSTRAP)
 endmacro()
 
 macro(EZVCPKG_BUILD)
-    set(INSTALL_COMMAND "${EZVCPKG_EXE}" --vcpkg-root "${EZVCPKG_DIR}" install --triplet ${VCPKG_TRIPLET})
+    set(INSTALL_COMMAND "${EZVCPKG_EXE}" --allow-unsupported --vcpkg-root "${EZVCPKG_DIR}" install --triplet ${VCPKG_TRIPLET})
 
     if (DEFINED VCPKG_OVERLAY_PORTS)
         if (CMAKE_HOST_WIN32)

cmake/modules/Findmodp_b64.cmake

@@ -9,7 +9,7 @@ find_library(modp_b64_DEBUG_LIBRARIES
 
 # vcpkg specific locations for debug libraries if they are not already found
 set(modpbase64SavePrefixPath ${CMAKE_PREFIX_PATH})
-list(FILTER CMAKE_PREFIX_PATH INCLUDE REGEX "/debug")
+list(FILTER CMAKE_PREFIX_PATH INCLUDE REGEX "/debug$")
 find_library(modp_b64_DEBUG_LIBRARIES
   NAMES
   modpbase64
@@ -18,7 +18,7 @@ find_library(modp_b64_DEBUG_LIBRARIES
 set(CMAKE_PREFIX_PATH ${modpbase64SavePrefixPath})
 
 set(modpbase64SavePrefixPath ${CMAKE_PREFIX_PATH})
-list(FILTER CMAKE_PREFIX_PATH EXCLUDE REGEX "/debug")
+list(FILTER CMAKE_PREFIX_PATH EXCLUDE REGEX "/debug$")
 find_library(modp_b64_LIBRARIES NAMES modpbase64 libmodpbase64)
 set(CMAKE_PREFIX_PATH ${modpbase64SavePrefixPath})
 

extern/CMakeLists.txt

@@ -19,4 +19,4 @@ target_include_directories(earcut INTERFACE "${EARCUT_HPP_INCLUDE_DIRS}")
 add_library(picosha2::picosha2 IMPORTED INTERFACE GLOBAL)
 set_target_properties(picosha2::picosha2 PROPERTIES
     INTERFACE_INCLUDE_DIRECTORIES "${PACKAGE_BUILD_DIR}/include"
-)
+)

extern/vcpkg/ports/ktx/portfile.cmake

@@ -0,0 +1,77 @@
+vcpkg_from_github(
+    OUT_SOURCE_PATH SOURCE_PATH
+    REPO kring/KTX-Software # KhronosGroup/KTX-Software
+    REF "v${VERSION}"
+    SHA512 fa20457fc0f0b117f4d6b406baa338091a85bcc46f60ca440dcd483388c67c550c81da3618d70d748e12850e32e0c1d82e9e8dc8522849074f40cc455723ac97
+    HEAD_REF master
+)
+file(REMOVE "${SOURCE_PATH}/other_include/zstd_errors.h")
+file(REMOVE_RECURSE "${SOURCE_PATH}/external/basisu/zstd")
+file(REMOVE_RECURSE "${SOURCE_PATH}/lib/basisu/zstd")
+
+vcpkg_list(SET OPTIONS)
+if(VCPKG_TARGET_IS_WINDOWS)
+    vcpkg_acquire_msys(MSYS_ROOT
+        PACKAGES
+            bash
+        DIRECT_PACKAGES
+            # Required for "getopt"
+            "https://mirror.msys2.org/msys/x86_64/util-linux-2.40.2-2-x86_64.pkg.tar.zst"
+            bf45b16cd470f8d82a9fe03842a09da2e6c60393c11f4be0bab354655072c7a461afc015b9c07f9f5c87a0e382cd867e4f079ede0d42f1589aa99ebbb3f76309
+            # Required for "dos2unix"
+            "https://mirror.msys2.org/msys/x86_64/dos2unix-7.5.3-1-x86_64.pkg.tar.zst"
+            ab5f88b10577b1d195d9b7b74c1a46d9e715c5fac21e8da3d590f345294190ed1ce7fde37d765f51ba01c2f6706c077123d4c69cfd0981729fdcb3d30f85bc6d
+    )
+    vcpkg_add_to_path("${MSYS_ROOT}/usr/bin")
+    vcpkg_list(APPEND OPTIONS "-DBASH_EXECUTABLE=${MSYS_ROOT}/usr/bin/bash.exe")
+endif()
+
+vcpkg_check_features(OUT_FEATURE_OPTIONS FEATURE_OPTIONS
+    FEATURES
+        tools   KTX_FEATURE_TOOLS
+        vulkan  LIBKTX_FEATURE_VK_UPLOAD
+        js      KTX_FEATURE_JS
+)
+
+vcpkg_cmake_configure(
+    SOURCE_PATH "${SOURCE_PATH}"
+    OPTIONS
+        -DKTX_GIT_VERSION_FULL=v${VERSION}
+        -DKTX_FEATURE_TESTS=OFF
+        -DKTX_FEATURE_LOADTEST_APPS=OFF
+        -DKTX_FEATURE_EMBEDDED_ZSTD=OFF
+        -DKTX_FEATURE_EMBEDDED_TOOLS_DEPENDENCIES=OFF
+        -DLIBKTX_FEATURE_APPLE_FRAMEWORK=OFF
+        ${FEATURE_OPTIONS}
+        ${OPTIONS}
+    DISABLE_PARALLEL_CONFIGURE
+)
+
+vcpkg_cmake_install()
+
+if(tools IN_LIST FEATURES)
+    vcpkg_copy_tools(
+        TOOL_NAMES
+            ktx
+            toktx
+            ktxsc
+            ktxinfo
+            ktx2ktx2
+            ktx2check
+        AUTO_CLEAN
+    )
+else()
+    vcpkg_copy_pdbs()
+endif()
+
+vcpkg_cmake_config_fixup(CONFIG_PATH lib/cmake/ktx)
+
+file(REMOVE_RECURSE "${CURRENT_PACKAGES_DIR}/debug/include")
+
+if(VCPKG_LIBRARY_LINKAGE STREQUAL "static")
+    file(REMOVE_RECURSE "${CURRENT_PACKAGES_DIR}/bin" "${CURRENT_PACKAGES_DIR}/debug/bin")
+endif()
+
+file(GLOB LICENSE_FILES "${SOURCE_PATH}/LICENSES/*")
+file(COPY ${LICENSE_FILES} DESTINATION "${CURRENT_PACKAGES_DIR}/share/${PORT}/LICENSES")
+vcpkg_install_copyright(FILE_LIST "${SOURCE_PATH}/LICENSE.md")

extern/vcpkg/ports/ktx/vcpkg.json

@@ -0,0 +1,46 @@
+{
+  "name": "ktx",
+  "version-semver": "4.4.2-plus-vcpkg-patches",
+  "description": [
+    "The Khronos KTX library and tools.",
+    "Functions for writing and reading KTX files, and instantiating OpenGL®, OpenGL ES™️ and Vulkan® textures from them."
+  ],
+  "homepage": "https://github.com/KhronosGroup/KTX-Software",
+  "license": null,
+  "supports": "arm64 | x64 | !windows",
+  "dependencies": [
+    {
+      "name": "vcpkg-cmake",
+      "host": true
+    },
+    {
+      "name": "vcpkg-cmake-config",
+      "host": true
+    },
+    "zstd"
+  ],
+  "features": {
+    "tools": {
+      "description": "Build tools",
+      "supports": "!android & !uwp",
+      "dependencies": [
+        "cxxopts",
+        "fmt"
+      ]
+    },
+    "vulkan": {
+      "description": "Build Vulkan support",
+      "supports": "!emscripten"
+    },
+    "js": {
+      "description": "Build JavaScript interface wrappers",
+      "supports": "emscripten"
+    }
+  },
+  "default-features": [
+    {
+      "name": "js",
+      "platform": "emscripten"
+    }
+  ]
+}

extern/vcpkg/triplets/wasm32-emscripten-cesium.cmake

@@ -0,0 +1,29 @@
+set(VCPKG_ENV_PASSTHROUGH_UNTRACKED EMSCRIPTEN_ROOT EMSDK PATH EM_CONFIG)
+
+if(NOT DEFINED ENV{EMSCRIPTEN_ROOT})
+   find_path(EMSCRIPTEN_ROOT "emcc")
+else()
+   set(EMSCRIPTEN_ROOT "$ENV{EMSCRIPTEN_ROOT}")
+endif()
+
+if(NOT EMSCRIPTEN_ROOT)
+   if(NOT DEFINED ENV{EMSDK})
+      message(FATAL_ERROR "The emcc compiler not found in PATH")
+   endif()
+   set(EMSCRIPTEN_ROOT "$ENV{EMSDK}/upstream/emscripten")
+endif()
+
+if(NOT EXISTS "${EMSCRIPTEN_ROOT}/cmake/Modules/Platform/Emscripten.cmake")
+   message(FATAL_ERROR "Emscripten.cmake toolchain file not found")
+endif()
+
+set(VCPKG_TARGET_ARCHITECTURE wasm32)
+set(VCPKG_CRT_LINKAGE dynamic)
+set(VCPKG_LIBRARY_LINKAGE static)
+set(VCPKG_CMAKE_SYSTEM_NAME Emscripten)
+set(VCPKG_CHAINLOAD_TOOLCHAIN_FILE "${EMSCRIPTEN_ROOT}/cmake/Modules/Platform/Emscripten.cmake")
+
+# These lines are the key difference between this triplet and the wasm32-emscripten that comes with vcpkg.
+# They set specific compiler and linker flags needed to use cesium-native on the web, particularly as part of Unity.
+set(_configureFlags "-pthread -msimd128 -mnontrapping-fptoint -mbulk-memory -fwasm-exceptions -sSUPPORT_LONGJMP=wasm -DSIZEOF_SIZE_T=4")
+set(VCPKG_CMAKE_CONFIGURE_OPTIONS -DCMAKE_C_FLAGS=${_configureFlags} -DCMAKE_CXX_FLAGS=${_configureFlags} -DCMAKE_EXE_LINKER_FLAGS=${_configureFlags})

extern/vcpkg/triplets/wasm64-emscripten-cesium.cmake

@@ -0,0 +1,29 @@
+set(VCPKG_ENV_PASSTHROUGH_UNTRACKED EMSCRIPTEN_ROOT EMSDK PATH EM_CONFIG)
+
+if(NOT DEFINED ENV{EMSCRIPTEN_ROOT})
+   find_path(EMSCRIPTEN_ROOT "emcc")
+else()
+   set(EMSCRIPTEN_ROOT "$ENV{EMSCRIPTEN_ROOT}")
+endif()
+
+if(NOT EMSCRIPTEN_ROOT)
+   if(NOT DEFINED ENV{EMSDK})
+      message(FATAL_ERROR "The emcc compiler not found in PATH")
+   endif()
+   set(EMSCRIPTEN_ROOT "$ENV{EMSDK}/upstream/emscripten")
+endif()
+
+if(NOT EXISTS "${EMSCRIPTEN_ROOT}/cmake/Modules/Platform/Emscripten.cmake")
+   message(FATAL_ERROR "Emscripten.cmake toolchain file not found")
+endif()
+
+set(VCPKG_TARGET_ARCHITECTURE wasm32)
+set(VCPKG_CRT_LINKAGE dynamic)
+set(VCPKG_LIBRARY_LINKAGE static)
+set(VCPKG_CMAKE_SYSTEM_NAME Emscripten)
+set(VCPKG_CHAINLOAD_TOOLCHAIN_FILE "${EMSCRIPTEN_ROOT}/cmake/Modules/Platform/Emscripten.cmake")
+
+# These lines are the key difference between this triplet and the wasm32-emscripten that comes with vcpkg.
+# They set specific compiler and linker flags needed to use cesium-native on the web, particularly as part of Unity.
+set(_configureFlags "-sMEMORY64=1 -pthread -msimd128 -mnontrapping-fptoint -mbulk-memory -fwasm-exceptions -sSUPPORT_LONGJMP=wasm -DSIZEOF_SIZE_T=8")
+set(VCPKG_CMAKE_CONFIGURE_OPTIONS -DCMAKE_C_FLAGS=${_configureFlags} -DCMAKE_CXX_FLAGS=${_configureFlags} -DCMAKE_EXE_LINKER_FLAGS=${_configureFlags})

package.json

@@ -1,6 +1,6 @@
 {
   "name": "cesium-native",
-  "version": "0.53.0",
+  "version": "0.54.0",
   "description": "Cesium 3D Geospatial for C++",
   "main": "index.js",
   "directories": {
@@ -12,7 +12,8 @@
     "generate-gltf": "cd tools/generate-classes && npm run generate-gltf && cd ../.. && npm run format",
     "generate-3d-tiles": "cd tools/generate-classes && npm run generate-3d-tiles && cd ../.. && npm run format",
     "generate-quantized-mesh-terrain": "cd tools/generate-classes && npm run generate-quantized-mesh-terrain && cd ../.. && npm run format",
-    "conform-includes": "node tools/conform-includes.js"
+    "conform-includes": "node tools/conform-includes.js",
+    "test-wasm": "node tools/test-wasm-server"
   },
   "repository": {
     "type": "git",
@@ -31,6 +32,7 @@
   "homepage": "https://github.com/CesiumGS/cesium-native#readme",
   "devDependencies": {
     "clang-format": "^1.5.0",
-    "doxygen-awesome-css": "https://github.com/jothepro/doxygen-awesome-css#v2.3.4"
+    "doxygen-awesome-css": "https://github.com/jothepro/doxygen-awesome-css#v2.3.4",
+    "express": "^5.1.0"
   }
 }

tools/generate-classes/glTF.json

@@ -163,6 +163,12 @@
     },
     "EXT_primitive_voxels glTF Mesh Primitive extension": {
       "overrideName": "ExtensionExtPrimitiveVoxels"
+    },
+    "KHR_gaussian_splatting glTF Mesh Primitive Extension": {
+      "overrideName": "ExtensionKhrGaussianSplatting"
+    },
+    "KHR_gaussian_splatting_compression_spz_2 glTF Mesh Primitive Extension": {
+      "overrideName": "ExtensionKhrGaussianSplattingCompressionSpz2"
     }
   },
   "extensions": [
@@ -287,6 +293,20 @@
     {
       "extensionName": "EXT_primitive_voxels",
       "schema": "Vendor/EXT_primitive_voxels/schema/mesh.primitive.EXT_primitive_voxels.schema.json"
+    },
+    {
+      "extensionName": "KHR_gaussian_splatting",
+      "schema": "Khronos/KHR_gaussian_splatting/schema/mesh.primitive.KHR_gaussian_splatting.schema.json",
+      "attachTo": [
+        "mesh.primitive"
+      ]
+    },
+    {
+      "extensionName": "KHR_gaussian_splatting_compression_spz_2",
+      "schema": "Khronos/KHR_gaussian_splatting_compression_spz_2/schema/mesh.primitive.KHR_gaussian_splatting_compression_spz_2.schema.json",
+      "attachTo": [
+        "mesh.primitive.KHR_gaussian_splatting"
+      ]
     }
   ]
 }

tools/generate-classes/makeIdentifier.js

@@ -1,5 +1,5 @@
 function makeIdentifier(s) {
-  return s.replace(/\//g, "_");
+  return s.replace(/[\/\.-]/g, "_");
 }
 
 module.exports = makeIdentifier;

tools/test-wasm-server/index.js

@@ -0,0 +1,56 @@
+const express = require("express");
+const fs = require("fs");
+
+const app = express();
+const port = 3123;
+
+app.use(express.static("./", {
+  setHeaders: (res, path, stat) => {
+    res.set("Cross-Origin-Opener-Policy", "same-origin");
+    res.set("Cross-Origin-Embedder-Policy", "require-corp");
+  }
+}));
+
+const emsdk = process.env.EMSDK;
+
+if (emsdk && emsdk.length > 0) {
+  console.log(`Using emsdk at: ${emsdk}`);
+
+  app.use("/emsdk/emscripten", express.static(`${emsdk}/upstream/emscripten`, {
+    setHeaders: (res, path, stat) => {
+      res.set("Cross-Origin-Opener-Policy", "same-origin");
+      res.set("Cross-Origin-Embedder-Policy", "require-corp");
+    }
+  }));
+
+  app.use("/emsdk/upstream", express.static(`${emsdk}/upstream`, {
+    setHeaders: (res, path, stat) => {
+      res.set("Cross-Origin-Opener-Policy", "same-origin");
+      res.set("Cross-Origin-Embedder-Policy", "require-corp");
+    }
+  }));
+} else {
+  console.log("Not mapping emsdk path because EMSDK environment variable is not set.");
+}
+
+const ezvcpkg = process.env.EZVCPKG_BASEDIR;
+if (!ezvcpkg || ezvcpkg.length === 0) {
+  ezvcpkg = `${process.env.HOME ?? ""}/.ezvcpkg`;
+}
+
+if (fs.existsSync(ezvcpkg)) {
+  console.log(`Using ezvcpkg at: ${ezvcpkg}`);
+  
+  app.use("/ezvcpkg", express.static(ezvcpkg, {
+    setHeaders: (res, path, stat) => {
+      res.set("Cross-Origin-Opener-Policy", "same-origin");
+      res.set("Cross-Origin-Embedder-Policy", "require-corp");
+    }
+  }));
+} else {
+  console.log("Not mapping ezvcpkg path because EZVCPKG_BASEDIR environment variable is not set or directory does not exist.");
+}
+
+app.listen(port, () => {
+  console.log(`listening on port ${port}`);
+});

vcpkg-configuration.json

@@ -1,7 +1,7 @@
 {
     "default-registry": {
         "kind": "git",
-        "baseline": "4334d8b4c8916018600212ab4dd4bbdc343065d1",
+        "baseline": "afc0a2e01ae104a2474216a2df0e8d78516fd5af",
         "repository": "https://github.com/microsoft/vcpkg"
     },
     "registries": [

vcpkg.json

@@ -2,7 +2,10 @@
   "$schema": "https://raw.githubusercontent.com/microsoft/vcpkg-tool/main/docs/vcpkg.schema.json",
   "dependencies": [
     "asyncplusplus",
-    "curl",
+    {
+      "name": "curl",
+      "platform": "!wasm32"
+    },
     "doctest",
     "expected-lite",
     "glm",
@@ -24,7 +27,10 @@
     "zlib-ng",
     "picosha2",
     "earcut-hpp",
-    "cpp-httplib",
+    {
+      "name": "cpp-httplib",
+      "platform": "!wasm32"
+    },
     "libmorton",
     "zstd",
     {
@@ -33,14 +39,16 @@
       "features": [
         {
           "name": "jit",
-          "platform": "!ios"
+          "platform": "!ios&!wasm32"
         }
       ]
     },
     {
       "name": "asmjit",
-      "platform": "!ios"
-    }
+      "platform": "!ios&!wasm32"
+    },
+    "spz",
+    "zlib"
   ]
 }