Billboard clamping

CHANGES.md

@@ -10,6 +10,7 @@
 - Fixed error when there are duplicated points in polygon/polyline geometries with `ArcType.RHUMB` [#12460](https://github.com/CesiumGS/cesium/pull/12460)
 - Fixed ground atmosphere shaders in 3D orthographic mode [#12484](https://github.com/CesiumGS/cesium/pull/12484)
 - Fixed zoom in 3D orthographic mode [#12483](https://github.com/CesiumGS/cesium/pull/12483)
+- Fixed issue with billboards not clamping properly when nested inside a PrimitiveCollection [#12482](https://github.com/CesiumGS/cesium/pull/12482)
 
 ## 1.126 - 2025-02-03
 

CONTRIBUTORS.md

@@ -425,3 +425,4 @@ See [CONTRIBUTING.md](CONTRIBUTING.md) for details on how to contribute to Cesiu
 - [Parth Petkar](https://github.com/parthpetkar)
 - [Yutao Liu](https://github.com/liuyutao)
 - [Andrew Dassonville](https://github.com/andrewda)
+- [Cody Butler](https://github.com/CodyBu)

packages/engine/Source/Scene/Scene.js

@@ -3805,6 +3805,38 @@ function getGlobeHeight(scene) {
   return scene.getHeight(cartographic);
 }
 
+function getMaxPrimitiveHeight(primitive, cartographic, scene) {
+  let maxHeight = Number.NEGATIVE_INFINITY;
+
+  if (defined(primitive.length)) {
+    // If it's a PrimitiveCollection, iterate through its children
+    const length = primitive.length;
+    for (let i = 0; i < length; ++i) {
+      const subPrimitive = primitive.get(i);
+      const subHeight = getMaxPrimitiveHeight(
+        subPrimitive,
+        cartographic,
+        scene,
+      );
+      if (defined(subHeight) && subHeight > maxHeight) {
+        maxHeight = subHeight;
+      }
+    }
+  } else if (
+    primitive.isCesium3DTileset &&
+    primitive.show &&
+    primitive.enableCollision
+  ) {
+    // If it's an individual primitive, check its height
+    const result = primitive.getHeight(cartographic, scene);
+    if (defined(result) && result > maxHeight) {
+      return result;
+    }
+  }
+
+  return maxHeight;
+}
+
 /**
  * Gets the height of the loaded surface at the cartographic position.
  * @param {Cartographic} cartographic The cartographic position.
@@ -3831,21 +3863,13 @@ Scene.prototype.getHeight = function (cartographic, heightReference) {
   let maxHeight = Number.NEGATIVE_INFINITY;
 
   if (!ignore3dTiles) {
-    const length = this.primitives.length;
-    for (let i = 0; i < length; ++i) {
-      const primitive = this.primitives.get(i);
-      if (
-        !primitive.isCesium3DTileset ||
-        !primitive.show ||
-        !primitive.enableCollision
-      ) {
-        continue;
-      }
-
-      const result = primitive.getHeight(cartographic, this);
-      if (defined(result) && result > maxHeight) {
-        maxHeight = result;
-      }
+    const maxPrimitiveHeight = getMaxPrimitiveHeight(
+      this.primitives,
+      cartographic,
+      this,
+    );
+    if (defined(maxPrimitiveHeight) && maxPrimitiveHeight > maxHeight) {
+      maxHeight = maxPrimitiveHeight;
     }
   }
 

packages/engine/Specs/Scene/SceneSpec.js

@@ -47,6 +47,7 @@ import {
   PerInstanceColorAppearance,
   ColorGeometryInstanceAttribute,
   Resource,
+  HeightReference,
 } from "../../index.js";
 
 import createCanvas from "../../../../Specs/createCanvas.js";
@@ -2944,6 +2945,37 @@ describe(
 
       expect(mockTileset.updateHeight).toHaveBeenCalled();
     });
+
+    it("adds nested primitive collection to scene", function () {
+      const expectedHeight = 100;
+
+      const mockTileset = new TilesetMockPrimitive();
+      mockTileset.enableCollision = true;
+      mockTileset.getHeight = function () {
+        return expectedHeight;
+      };
+      mockTileset.heightReference = HeightReference.CLAMP_TO_GROUND;
+
+      const mockTileset2 = new TilesetMockPrimitive();
+      mockTileset2.enableCollision = true;
+      mockTileset2.getHeight = function () {
+        return 80;
+      };
+      mockTileset2.heightReference = HeightReference.CLAMP_TO_GROUND;
+
+      const nestedCollection = new PrimitiveCollection();
+      nestedCollection.add(mockTileset);
+      nestedCollection.add(mockTileset2);
+
+      scene.primitives.add(nestedCollection);
+
+      const actualHeight = scene.getHeight(
+        scene.camera.positionCartographic,
+        HeightReference.CLAMP_TO_GROUND,
+      );
+
+      expect(actualHeight).toEqual(expectedHeight);
+    });
   },
 
   describe("pickMetadata", () => {