Add formal constant for voxel extension

CHANGES.md

@@ -10,6 +10,7 @@
 
 - Added a constructor overload for `Cesium3DTilesSelection::ITwinCesiumCuratedContentLoaderFactory` to override the iTwin Cesium Curated Content base URL. This makes it possible to connect to alternate servers (e.g., staging, QA, mock servers).
 - Added `ViewUpdateResult::tileScreenSpaceErrorThisFrame`, which stores the screen space errors computed for tiles in `tilesToRenderThisFrame`.
+- Added `CesiumGltf::ExtensionExtPrimitiveVoxels::MODE`, representing the primitive mode constant used by the extension.
 
 ##### Fixes :wrench:
 

CesiumGltf/generated/include/CesiumGltf/ExtensionExtPrimitiveVoxels.h → CesiumGltf/generated/include/CesiumGltf/ExtensionExtPrimitiveVoxelsSpec.h

@@ -17,7 +17,7 @@ namespace CesiumGltf {
  * @brief `EXT_primitive_voxels` extension for a primitive in a glTF model to
  * indicate voxel-based volumetric data
  */
-struct CESIUMGLTF_API ExtensionExtPrimitiveVoxels final
+struct CESIUMGLTF_API ExtensionExtPrimitiveVoxelsSpec
     : public CesiumUtility::ExtensibleObject {
   /**
    * @brief The original name of this type.
@@ -60,7 +60,7 @@ struct CESIUMGLTF_API ExtensionExtPrimitiveVoxels final
    */
   int64_t getSizeBytes() const {
     int64_t accum = 0;
-    accum += int64_t(sizeof(ExtensionExtPrimitiveVoxels));
+    accum += int64_t(sizeof(ExtensionExtPrimitiveVoxelsSpec));
     accum += CesiumUtility::ExtensibleObject::getSizeBytes() -
              int64_t(sizeof(CesiumUtility::ExtensibleObject));
     accum += int64_t(sizeof(int64_t) * this->dimensions.capacity());
@@ -77,5 +77,12 @@ struct CESIUMGLTF_API ExtensionExtPrimitiveVoxels final
     }
     return accum;
   }
+
+protected:
+  /**
+   * @brief This class is not meant to be instantiated directly. Use {@link ExtensionExtPrimitiveVoxels} instead.
+   */
+  ExtensionExtPrimitiveVoxelsSpec() = default;
+  friend struct ExtensionExtPrimitiveVoxels;
 };
 } // namespace CesiumGltf

CesiumGltf/include/CesiumGltf/ExtensionExtPrimitiveVoxels.h

@@ -0,0 +1,19 @@
+#pragma once
+
+#include <CesiumGltf/ExtensionExtPrimitiveVoxelsSpec.h>
+
+namespace CesiumGltf {
+
+/** @copydoc ExtensionExtPrimitiveVoxelsSpec */
+struct CESIUMGLTF_API ExtensionExtPrimitiveVoxels final
+    : public ExtensionExtPrimitiveVoxelsSpec {
+  /**
+   * @brief The constant used to indicate a voxel primitive in \ref
+   * CesiumGltf::MeshPrimitive::mode.
+   */
+  static constexpr int32_t MODE = 2147483647;
+
+  ExtensionExtPrimitiveVoxels() = default;
+};
+
+} // namespace CesiumGltf

tools/generate-classes/glTF.json

@@ -162,7 +162,8 @@
       "overrideName": "ExtensionExtImplicitCylinderRegion"
     },
     "EXT_primitive_voxels glTF Mesh Primitive extension": {
-      "overrideName": "ExtensionExtPrimitiveVoxels"
+      "overrideName": "ExtensionExtPrimitiveVoxels",
+      "toBeInherited": true
     },
     "KHR_gaussian_splatting glTF Mesh Primitive Extension": {
       "overrideName": "ExtensionKhrGaussianSplatting",