Create reference implementation for BENTLEY_materials_point_style

CHANGES.md

@@ -24,6 +24,10 @@
 
 - Beginning in CesiumJS 1.140, billboards and labels will require device support for WebGL 2, or WebGL 1 with ANGLE_instanced_arrays and MAX_VERTEX_TEXTURE_IMAGE_UNITS > 0. For more information or to share feedback, please see [#13053](https://github.com/CesiumGS/cesium/issues/13053). [#13067](https://github.com/CesiumGS/cesium/issues/13067)
 
+#### Additions :tada:
+
+- Added support for the proposed [BENTLEY_materials_point_style](https://github.com/CesiumGS/glTF/pull/91) glTF extension. This allows point primitives to have a diameter property specified and respected when loaded via glTF.
+
 ## 1.136 - 2025-12-01
 
 ### @cesium/engine

Specs/Data/Models/glTF-2.0/StyledPoints/points-r5-g8-b14-y10.gltf

@@ -0,0 +1,222 @@
+{
+    "asset": {
+        "version": "2.0"
+    },
+    "extensionsUsed": [
+        "BENTLEY_materials_point_style"
+    ],
+    "accessors": [
+        {
+            "bufferView": 0,
+            "byteOffset": 0,
+            "componentType": 5126,
+            "count": 4,
+            "type": "VEC3",
+            "max": [
+                5.0,
+                5.0,
+                5.0
+            ],
+            "min": [
+                -5.0,
+                -5.0,
+                -5.0
+            ]
+        },
+        {
+            "bufferView": 1,
+            "byteOffset": 0,
+            "componentType": 5123,
+            "count": 1,
+            "type": "SCALAR",
+            "max": [
+                0
+            ],
+            "min": [
+                0
+            ]
+        },
+        {
+            "bufferView": 1,
+            "byteOffset": 4,
+            "componentType": 5123,
+            "count": 1,
+            "type": "SCALAR",
+            "max": [
+                1
+            ],
+            "min": [
+                1
+            ]
+        },
+        {
+            "bufferView": 1,
+            "byteOffset": 8,
+            "componentType": 5123,
+            "count": 1,
+            "type": "SCALAR",
+            "max": [
+                2
+            ],
+            "min": [
+                2
+            ]
+        },
+        {
+            "bufferView": 1,
+            "byteOffset": 12,
+            "componentType": 5123,
+            "count": 1,
+            "type": "SCALAR",
+            "max": [
+                3
+            ],
+            "min": [
+                3
+            ]
+        }
+    ],
+    "buffers": [
+        {
+            "byteLength": 64,
+            "uri": "data:application/octet-stream;base64,AACgwAAAoMAAAKDAAACgQAAAoMAAAKDAAAAAAAAAoEAAAKDAAAAAAAAAAAAAAKBAAAAAAAEAAAACAAAAAwAAAA=="
+        }
+    ],
+    "bufferViews": [
+        {
+            "buffer": 0,
+            "byteOffset": 0,
+            "byteLength": 48,
+            "target": 34962
+        },
+        {
+            "buffer": 0,
+            "byteOffset": 48,
+            "byteLength": 16,
+            "target": 34963
+        }
+    ],
+    "materials": [
+        {
+            "name": "Red",
+            "pbrMetallicRoughness": {
+                "baseColorFactor": [
+                    1.0,
+                    0.0,
+                    0.0,
+                    1.0
+                ],
+                "metallicFactor": 0.0
+            },
+            "extensions": {
+                "BENTLEY_materials_point_style": {
+                    "diameter": 5.0
+                }
+            }
+        },
+        {
+            "name": "Green",
+            "pbrMetallicRoughness": {
+                "baseColorFactor": [
+                    0.0,
+                    1.0,
+                    0.0,
+                    1.0
+                ],
+                "metallicFactor": 0.0
+            },
+            "extensions": {
+                "BENTLEY_materials_point_style": {
+                    "diameter": 8.0
+                }
+            }
+        },
+        {
+            "name": "Blue",
+            "pbrMetallicRoughness": {
+                "baseColorFactor": [
+                    0.0,
+                    0.0,
+                    1.0,
+                    1.0
+                ],
+                "metallicFactor": 0.0
+            },
+            "extensions": {
+                "BENTLEY_materials_point_style": {
+                    "diameter": 14.0
+                }
+            }
+        },
+        {
+            "name": "Yellow",
+            "pbrMetallicRoughness": {
+                "baseColorFactor": [
+                    1.0,
+                    1.0,
+                    0.0,
+                    1.0
+                ],
+                "metallicFactor": 0.0
+            },
+            "extensions": {
+                "BENTLEY_materials_point_style": {
+                    "diameter": 10.0
+                }
+            }
+        }
+    ],
+    "meshes": [
+        {
+            "name": "PointCloud",
+            "primitives": [
+                {
+                    "mode": 0,
+                    "material": 0,
+                    "indices": 1,
+                    "attributes": {
+                        "POSITION": 0
+                    }
+                },
+                {
+                    "mode": 0,
+                    "material": 1,
+                    "indices": 2,
+                    "attributes": {
+                        "POSITION": 0
+                    }
+                },
+                {
+                    "mode": 0,
+                    "material": 2,
+                    "indices": 3,
+                    "attributes": {
+                        "POSITION": 0
+                    }
+                },
+                {
+                    "mode": 0,
+                    "material": 3,
+                    "indices": 4,
+                    "attributes": {
+                        "POSITION": 0
+                    }
+                }
+            ]
+        }
+    ],
+    "nodes": [
+        {
+            "name": "PointCloudNode",
+            "mesh": 0
+        }
+    ],
+    "scenes": [
+        {
+            "nodes": [
+                0
+            ]
+        }
+    ],
+    "scene": 0
+}

packages/engine/Source/Scene/GltfLoader.js

@@ -1811,6 +1811,16 @@ function loadMaterial(loader, gltfMaterial, frameState) {
   material.alphaCutoff = gltfMaterial.alphaCutoff;
   material.doubleSided = gltfMaterial.doubleSided;
 
+  // BENTLEY_materials_point_style extension
+  const pointStyleExtension = extensions.BENTLEY_materials_point_style;
+  if (defined(pointStyleExtension) && defined(pointStyleExtension.diameter)) {
+    const diameter = pointStyleExtension.diameter;
+    // Validate that diameter is a positive integer as the extension specification requires.
+    if (diameter > 0 && Math.floor(diameter) === diameter) {
+      material.pointDiameter = diameter;
+    }
+  }
+
   return material;
 }
 

packages/engine/Source/Scene/Model/MaterialPipelineStage.js

@@ -167,6 +167,23 @@ MaterialPipelineStage.process = function (
     alphaOptions.alphaCutoff = material.alphaCutoff;
   }
 
+  // Configure and handle point diameter for POINTS primitives (BENTLEY_materials_point_style extension).
+  if (defined(material.pointDiameter)) {
+    shaderBuilder.addDefine(
+      "HAS_POINT_DIAMETER",
+      undefined,
+      ShaderDestination.VERTEX,
+    );
+    shaderBuilder.addUniform(
+      "float",
+      "u_pointDiameter",
+      ShaderDestination.VERTEX,
+    );
+    uniformMap.u_pointDiameter = function () {
+      return material.pointDiameter * frameState.pixelRatio;
+    };
+  }
+
   shaderBuilder.addFragmentLines(MaterialStageFS);
 
   if (material.doubleSided) {

packages/engine/Source/Scene/ModelComponents.js

@@ -1623,6 +1623,16 @@ function Material() {
    * @private
    */
   this.unlit = false;
+
+  /**
+   * The point diameter in pixels for POINTS primitives. This is set by the
+   * BENTLEY_materials_point_style extension.
+   *
+   * @type {number}
+   * @default undefined
+   * @private
+   */
+  this.pointDiameter = undefined;
 }
 
 /**

packages/engine/Source/Shaders/Model/ModelFS.glsl

@@ -29,6 +29,14 @@ SelectedFeature selectedFeature;
 
 void main()
 {
+    #ifdef PRIMITIVE_TYPE_POINTS
+    // Render points as circles
+    float distanceToCenter = length(gl_PointCoord - vec2(0.5));
+    if (distanceToCenter > 0.5) {
+        discard;
+    }
+    #endif
+
     #ifdef HAS_POINT_CLOUD_SHOW_STYLE
         if (v_pointCloudShow == 0.0)
         {

packages/engine/Source/Shaders/Model/ModelVS.glsl

@@ -142,6 +142,8 @@ void main()
         gl_PointSize = vsOutput.pointSize;
         #elif defined(HAS_POINT_CLOUD_POINT_SIZE_STYLE) || defined(HAS_POINT_CLOUD_ATTENUATION)
         gl_PointSize = pointCloudPointSizeStylingStage(attributes, metadata);
+        #elif defined(HAS_POINT_DIAMETER)
+        gl_PointSize = u_pointDiameter;
         #else
         gl_PointSize = 1.0;
         #endif

packages/engine/Specs/Scene/GltfLoaderSpec.js

@@ -128,6 +128,8 @@ describe(
       "./Data/Models/glTF-2.0/BoxAnisotropy/glTF/BoxAnisotropy.gltf";
     const clearcoatTestData =
       "./Data/Models/glTF-2.0/BoxClearcoat/glTF/BoxClearcoat.gltf";
+    const pointStyleTestData =
+      "./Data/Models/glTF-2.0/StyledPoints/points-r5-g8-b14-y10.gltf";
     const meshPrimitiveRestartTestData =
       "./Data/Models/glTF-2.0/MeshPrimitiveRestart/glTF/MeshPrimitiveRestart.gltf";
     const edgeVisibilityTestData =
@@ -4176,6 +4178,57 @@ describe(
       expect(clearcoatNormalTexture.texture.width).toBe(256);
     });
 
+    it("loads model with BENTLEY_materials_point_style extension", async function () {
+      const gltfLoader = await loadGltf(pointStyleTestData);
+
+      // The test model has 4 primitives with different materials. Let's verify they all exist.
+      const primitives = gltfLoader.components.nodes[0].primitives;
+      expect(primitives.length).toBe(4);
+
+      // Check that pointDiameter was loaded correctly for each material. Each primitive has a different diameter.
+      expect(primitives[0].material.pointDiameter).toBe(5);
+      expect(primitives[1].material.pointDiameter).toBe(8);
+      expect(primitives[2].material.pointDiameter).toBe(14);
+      expect(primitives[3].material.pointDiameter).toBe(10);
+    });
+
+    it("ignores BENTLEY_materials_point_style with invalid negative diameter", async function () {
+      function modifyGltf(gltf) {
+        // Set an invalid negative diameter (diameters must be >0).
+        gltf.materials[0].extensions.BENTLEY_materials_point_style.diameter =
+          -5;
+        return gltf;
+      }
+
+      const gltfLoader = await loadModifiedGltfAndTest(
+        pointStyleTestData,
+        undefined,
+        modifyGltf,
+      );
+
+      // The invalid negative diameter should be ignored; property should be undefined once the glTF is loaded.
+      const material = gltfLoader.components.nodes[0].primitives[0].material;
+      expect(material.pointDiameter).toBeUndefined();
+    });
+
+    it("ignores BENTLEY_materials_point_style with non-integer diameter", async function () {
+      function modifyGltf(gltf) {
+        // Set an invalid non-integer diameter (diameters must be integers).
+        gltf.materials[0].extensions.BENTLEY_materials_point_style.diameter = 5.5;
+        return gltf;
+      }
+
+      const gltfLoader = await loadModifiedGltfAndTest(
+        pointStyleTestData,
+        undefined,
+        modifyGltf,
+      );
+
+      // Invalid non-integer diameter should be ignored; property should be undefined once the glTF is loaded.
+      const material = gltfLoader.components.nodes[0].primitives[0].material;
+      expect(material.pointDiameter).toBeUndefined();
+    });
+
     it("loads model with EXT_mesh_primitive_restart extension", async function () {
       const gltf = await Resource.fetchJson({
         url: meshPrimitiveRestartTestData,