mirror of https://github.com/CesiumGS/cesium.git
94 lines
2.9 KiB
JavaScript
94 lines
2.9 KiB
JavaScript
import * as Cesium from "cesium";
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const terrainProvider =
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await Cesium.Cesium3DTilesTerrainProvider.fromIonAssetId(3923568, {
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requestVertexNormals: true, // Needed for hillshade lighting
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requestWaterMask: true, // Needed to distinguish land from water
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});
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const viewer = new Cesium.Viewer("cesiumContainer", {
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terrainProvider: terrainProvider,
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scene3DOnly: true,
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sceneModePicker: false,
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navigationHelpButton: false,
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});
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// Create a globe material for shading elevation only on land
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const customElevationMaterial = new Cesium.Material({
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fabric: {
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type: "ElevationLand",
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materials: {
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waterMaskMaterial: {
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type: "WaterMask",
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},
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elevationRampMaterial: {
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type: "ElevationRamp",
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},
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},
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components: {
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diffuse: "elevationRampMaterial.diffuse",
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alpha: "1.0 - waterMaskMaterial.alpha", // We'll need the inverse of the watermask to shade land
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},
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},
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translucent: false,
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});
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const minHeight = -414.0; // approximate dead sea elevation
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const maxHeight = 8777.0; // approximate everest elevation
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const elevationRamp = [0.0, 0.045, 0.45, 0.5, 0.55, 1.0];
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function getColorRamp() {
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const ramp = document.createElement("canvas");
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ramp.width = 100;
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ramp.height = 1;
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const ctx = ramp.getContext("2d");
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const values = elevationRamp;
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const grd = ctx.createLinearGradient(0, 0, 100, 0);
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// See https://gis.stackexchange.com/questions/25099/choosing-colour-ramp-to-use-for-elevation
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grd.addColorStop(values[0], "#344f31");
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grd.addColorStop(values[1], "#5b8742");
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grd.addColorStop(values[2], "#e6daa5");
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grd.addColorStop(values[3], "#fdc771");
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grd.addColorStop(values[4], "#b99d89");
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grd.addColorStop(values[5], "#f0f0f0");
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ctx.fillStyle = grd;
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ctx.fillRect(0, 0, 100, 1);
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return ramp;
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}
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const globe = viewer.scene.globe;
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const material = customElevationMaterial;
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const shadingUniforms = material.materials.elevationRampMaterial.uniforms;
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globe.showWaterEffect = false;
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globe.enableLighting = true;
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shadingUniforms.minimumHeight = minHeight;
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shadingUniforms.maximumHeight = maxHeight;
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shadingUniforms.image = getColorRamp();
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globe.material = material;
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// Light the scene with a hillshade effect similar to https://pro.arcgis.com/en/pro-app/latest/tool-reference/3d-analyst/how-hillshade-works.htm
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const scene = viewer.scene;
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scene.light = new Cesium.DirectionalLight({
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direction: new Cesium.Cartesian3(1, 0, 0), // Updated every frame
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});
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// Update the light position base on the camera
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const scratchNormal = new Cesium.Cartesian3();
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scene.preRender.addEventListener(function (scene, time) {
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const surfaceNormal = Cesium.Ellipsoid.WGS84.geodeticSurfaceNormal(
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scene.camera.positionWC,
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scratchNormal,
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);
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const negativeNormal = Cesium.Cartesian3.negate(surfaceNormal, surfaceNormal);
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scene.light.direction = Cesium.Cartesian3.normalize(
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Cesium.Cartesian3.add(negativeNormal, scene.camera.rightWC, surfaceNormal),
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scene.light.direction,
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);
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});
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