Extract Vector glTF tile data into BufferPrimitiveCollection

Apps/SampleData/vector/sample-cities-spain.tileset.json

@@ -0,0 +1,17 @@
+{
+  "asset": { "version": "1.1" },
+  "extensionsUsed": [ "3DTILES_content_gltf" ],
+  "extensions": {
+    "3DTILES_content_gltf": {
+      "extensionsRequired": [ "CESIUM_mesh_vector" ],
+      "extensionsUsed": [ "CESIUM_mesh_vector" ]
+    }
+  },
+  "geometricError": 2000000.0,
+  "root": {
+    "boundingVolume": { "region": [ -0.14912553056282754, 0.630603674286057, 0.038089971913258434, 0.7585433514898835, -1000, 1000 ] },
+    "geometricError": 0.0,
+    "refine": "REPLACE",
+    "content": { "uri": "sample-cities-spain.glb" }
+  }
+}

Apps/SampleData/vector/sample-us-outline.tileset.json

@@ -0,0 +1,17 @@
+{
+  "asset": { "version": "1.1" },
+  "extensionsUsed": [ "3DTILES_content_gltf" ],
+  "extensions": {
+    "3DTILES_content_gltf": {
+      "extensionsRequired": [ "CESIUM_mesh_vector" ],
+      "extensionsUsed": [ "CESIUM_mesh_vector" ]
+    }
+  },
+  "geometricError": 2000000.0,
+  "root": {
+    "boundingVolume": { "region": [ -3.1267109291897386, 0.31214887295348465, 3.13772622569785, 1.2453371191800977, -1000, 1000 ] },
+    "geometricError": 0.0,
+    "refine": "REPLACE",
+    "content": { "uri": "sample-us-outline.glb" }
+  }
+}

Apps/SampleData/vector/sample-us-states.tileset.json

@@ -0,0 +1,17 @@
+{
+  "asset": { "version": "1.1" },
+  "extensionsUsed": [ "3DTILES_content_gltf" ],
+  "extensions": {
+    "3DTILES_content_gltf": {
+      "extensionsRequired": [ "CESIUM_mesh_vector" ],
+      "extensionsUsed": [ "CESIUM_mesh_vector" ]
+    }
+  },
+  "geometricError": 2000000.0,
+  "root": {
+    "boundingVolume": { "region": [ -3.1267109291897386, 0.31214887295348465, 3.13772622569785, 1.2453371191800977, -1000, 1000 ] },
+    "geometricError": 0.0,
+    "refine": "REPLACE",
+    "content": { "uri": "sample-us-states.glb" }
+  }
+}

packages/engine/Source/Scene/Cesium3DTileContentFactory.js

@@ -4,6 +4,7 @@ import Implicit3DTileContent from "./Implicit3DTileContent.js";
 import Model3DTileContent from "./Model/Model3DTileContent.js";
 import Tileset3DTileContent from "./Tileset3DTileContent.js";
 import Vector3DTileContent from "./Vector3DTileContent.js";
+import VectorGltf3DTileContent from "./VectorGltf3DTileContent.js";
 import GaussianSplat3DTileContent from "./GaussianSplat3DTileContent.js";
 import RuntimeError from "../Core/RuntimeError.js";
 
@@ -100,6 +101,10 @@ const Cesium3DTileContentFactory = {
       return GaussianSplat3DTileContent.fromGltf(tileset, tile, resource, glb);
     }
 
+    if (tileset.isGltfExtensionUsed("CESIUM_mesh_vector")) {
+      return VectorGltf3DTileContent.fromGltf(tileset, tile, resource, glb);
+    }
+
     return Model3DTileContent.fromGltf(tileset, tile, resource, glb);
   },
   gltf: function (tileset, tile, resource, json) {
@@ -109,6 +114,10 @@ const Cesium3DTileContentFactory = {
       return GaussianSplat3DTileContent.fromGltf(tileset, tile, resource, json);
     }
 
+    if (tileset.isGltfExtensionUsed("CESIUM_mesh_vector")) {
+      return VectorGltf3DTileContent.fromGltf(tileset, tile, resource, json);
+    }
+
     return Model3DTileContent.fromGltf(tileset, tile, resource, json);
   },
   geoJson: function (tileset, tile, resource, json) {

packages/engine/Source/Scene/Cesium3DTileset.js

@@ -3674,6 +3674,7 @@ Cesium3DTileset.supportedExtensions = {
   "3DTILES_bounding_volume_S2": true,
   "3DTILES_batch_table_hierarchy": true,
   "3DTILES_draco_point_compression": true,
+  CESIUM_mesh_vector: true,
   MAXAR_content_geojson: true,
 };
 

packages/engine/Source/Scene/GltfLoader.js

@@ -2055,6 +2055,10 @@ function loadPrimitive(loader, gltfPrimitive, hasInstances, frameState) {
   }
 
   const extensions = gltfPrimitive.extensions ?? Frozen.EMPTY_OBJECT;
+  const meshVectorExtension = extensions.CESIUM_mesh_vector;
+  if (defined(meshVectorExtension)) {
+    primitive.meshVector = loadMeshVectorExtension(loader, meshVectorExtension);
+  }
 
   let needsPostProcessing = false;
   const outlineExtension = extensions.CESIUM_primitive_outline;
@@ -2238,6 +2242,48 @@ function loadPrimitiveOutline(loader, outlineExtension) {
   return loadAccessor(loader, accessor, useQuaternion);
 }
 
+function loadMeshVectorExtension(loader, meshVectorExtension) {
+  if (!defined(meshVectorExtension)) {
+    return undefined;
+  }
+
+  const result = {
+    vector: meshVectorExtension.vector,
+    count: meshVectorExtension.count,
+  };
+
+  const accessors = loader.gltfJson.accessors;
+  function loadVectorAccessor(accessorId, name) {
+    if (!defined(accessorId)) {
+      return undefined;
+    }
+    const accessor = accessors[accessorId];
+    if (!defined(accessor)) {
+      throw new RuntimeError(`CESIUM_mesh_vector ${name} accessor not found!`);
+    }
+    return loadAccessor(loader, accessor);
+  }
+
+  result.polygonAttributeOffsets = loadVectorAccessor(
+    meshVectorExtension.polygonAttributeOffsets,
+    "polygonAttributeOffsets",
+  );
+  result.polygonHoleCounts = loadVectorAccessor(
+    meshVectorExtension.polygonHoleCounts,
+    "polygonHoleCounts",
+  );
+  result.polygonHoleOffsets = loadVectorAccessor(
+    meshVectorExtension.polygonHoleOffsets,
+    "polygonHoleOffsets",
+  );
+  result.polygonIndicesOffsets = loadVectorAccessor(
+    meshVectorExtension.polygonIndicesOffsets,
+    "polygonIndicesOffsets",
+  );
+
+  return result;
+}
+
 // For EXT_mesh_features
 function loadPrimitiveFeatures(
   loader,
@@ -2512,6 +2558,7 @@ function loadNode(loader, gltfNode, frameState) {
   const nodeExtensions = gltfNode.extensions ?? Frozen.EMPTY_OBJECT;
   const instancingExtension = nodeExtensions.EXT_mesh_gpu_instancing;
   const articulationsExtension = nodeExtensions.AGI_articulations;
+  const meshVectorExtension = nodeExtensions.CESIUM_mesh_vector;
 
   if (defined(instancingExtension)) {
     if (loader._loadForClassification) {
@@ -2526,6 +2573,10 @@ function loadNode(loader, gltfNode, frameState) {
     node.articulationName = articulationsExtension.articulationName;
   }
 
+  if (defined(meshVectorExtension)) {
+    node.meshVector = meshVectorExtension;
+  }
+
   const meshId = gltfNode.mesh;
   if (defined(meshId)) {
     const mesh = loader.gltfJson.meshes[meshId];