fix(textureatlas): Allocate texture space less aggressively on resize

fix(textureatlas): Apply internal padding between images

CHANGES.md

@@ -7,7 +7,9 @@
 #### Fixes :wrench:
 
 - Billboards using `imageSubRegion` now render as expected. [#12585](https://github.com/CesiumGS/cesium/issues/12585)
-- Improved scaling of SVGs in billboards [#TODO](https://github.com/CesiumGS/cesium/issues/TODO)
+- Improved scaling of SVGs in billboards [#13020](https://github.com/CesiumGS/cesium/issues/13020)
+- Fixed unexpected outline artifacts around billboards [#13038](https://github.com/CesiumGS/cesium/issues/13038)
+- Fixed image alignment in large billboard collections [#13042](https://github.com/CesiumGS/cesium/issues/13042)
 
 #### Additions :tada:
 

packages/engine/Source/Core/TexturePacker.js

@@ -122,6 +122,8 @@ TexturePacker.prototype._findNode = function (node, { width, height }) {
       return node;
     }
 
+    const borderPadding = this._borderPadding;
+
     // Vertical split (childNode1 = left half, childNode2 = right half).
     if (widthDifference > heightDifference) {
       node.childNode1 = new TextureNode({
@@ -130,12 +132,18 @@ TexturePacker.prototype._findNode = function (node, { width, height }) {
         width,
         height: nodeHeight,
       });
-      node.childNode2 = new TextureNode({
-        x: rectangle.x + width,
-        y: rectangle.y,
-        width: widthDifference,
-        height: nodeHeight,
-      });
+
+      // Apply padding only along the vertical "cut".
+      const widthDifferencePadded = widthDifference - borderPadding;
+
+      if (widthDifferencePadded > 0) {
+        node.childNode2 = new TextureNode({
+          x: rectangle.x + width + borderPadding,
+          y: rectangle.y,
+          width: widthDifferencePadded,
+          height: nodeHeight,
+        });
+      }
 
       return this._findNode(node.childNode1, { width, height });
     }
@@ -147,12 +155,19 @@ TexturePacker.prototype._findNode = function (node, { width, height }) {
       width: nodeWidth,
       height,
     });
-    node.childNode2 = new TextureNode({
-      x: rectangle.x,
-      y: rectangle.y + height,
-      width: nodeWidth,
-      height: heightDifference,
-    });
+
+    // Apply padding only along the horizontal "cut".
+    const heightDifferencePadded = heightDifference - borderPadding;
+
+    if (heightDifferencePadded > 0) {
+      node.childNode2 = new TextureNode({
+        x: rectangle.x,
+        y: rectangle.y + height + borderPadding,
+        width: nodeWidth,
+        height: heightDifferencePadded,
+      });
+    }
+
     return this._findNode(node.childNode1, { width, height });
   }
 

packages/engine/Source/Renderer/TextureAtlas.js

@@ -364,26 +364,17 @@ TextureAtlas.prototype._resize = function (context, queueOffset = 0) {
     toPack.push(queue[i]);
   }
 
-  // At minimum, the texture will need to scale to accommodate the largest width and height
-  width = Math.max(maxWidth, width);
-  height = Math.max(maxHeight, height);
+  // At minimum, atlas must fit its largest input images. Texture coordinates are
+  // compressed to 0–1 with 12-bit precision, so use power-of-two size to align pixels.
+  width = CesiumMath.nextPowerOfTwo(Math.max(maxWidth, width));
+  height = CesiumMath.nextPowerOfTwo(Math.max(maxHeight, height));
 
-  if (!context.webgl2) {
-    width = CesiumMath.nextPowerOfTwo(width);
-    height = CesiumMath.nextPowerOfTwo(height);
-  }
-
-  // Determine by what factor the texture need to be scaled by at minimum
-  const areaDifference = areaQueued;
-  let scalingFactor = 1.0;
-  while (areaDifference / width / height >= 1.0) {
-    scalingFactor *= 2.0;
-
-    // Resize by one dimension
+  // Iteratively double the smallest dimension until atlas area is (approximately) sufficient.
+  while (areaQueued >= width * height) {
     if (width > height) {
-      height *= scalingFactor;
+      height *= 2;
     } else {
-      width *= scalingFactor;
+      width *= 2;
     }
   }