Merge pull request #1757 from CesiumGS/detect-instanced-features

Make `GetPrimitiveFeatures` work for instanced meshes

Author: timoore

CHANGES.md

@@ -1,5 +1,11 @@
 # Change Log {#changes}
 
+### ? - ?
+
+##### Fixes :wrench:
+
+- Fixed a bug that prevented `UCesiumPrimitiveFeaturesBlueprintLibrary::GetPrimitiveFeatures` from retrieving the features of instanced meshes.
+
 ### v2.21.0 Preview for Unreal Engine 5.7 - 2025-11-17
 
 ##### Additions :tada:

Source/CesiumRuntime/Private/CesiumPrimitiveFeatures.cpp

@@ -44,13 +44,19 @@ FCesiumPrimitiveFeatures::FCesiumPrimitiveFeatures(
 const FCesiumPrimitiveFeatures&
 UCesiumPrimitiveFeaturesBlueprintLibrary::GetPrimitiveFeatures(
     const UPrimitiveComponent* component) {
+  const UCesiumGltfInstancedComponent* pGltfInstancedComponent =
+      Cast<UCesiumGltfInstancedComponent>(component);
+  if (IsValid(pGltfInstancedComponent)) {
+    return pGltfInstancedComponent->getPrimitiveData().Features;
+  }
+
   const UCesiumGltfPrimitiveComponent* pGltfComponent =
       Cast<UCesiumGltfPrimitiveComponent>(component);
-  if (!IsValid(pGltfComponent)) {
-    return EmptyPrimitiveFeatures;
+  if (IsValid(pGltfComponent)) {
+    return pGltfComponent->getPrimitiveData().Features;
   }
 
-  return pGltfComponent->getPrimitiveData().Features;
+  return EmptyPrimitiveFeatures;
 }
 
 const TArray<FCesiumFeatureIdSet>&

Source/CesiumRuntime/Private/Tests/CesiumPrimitiveFeatures.spec.cpp

@@ -1,10 +1,13 @@
 // Copyright 2020-2024 CesiumGS, Inc. and Contributors
 
 #include "CesiumPrimitiveFeatures.h"
-#include "CesiumGltf/ExtensionExtMeshFeatures.h"
+#include "CesiumGltfPrimitiveComponent.h"
 #include "CesiumGltfSpecUtility.h"
 #include "Misc/AutomationTest.h"
 
+#include <CesiumGltf/ExtensionExtInstanceFeatures.h>
+#include <CesiumGltf/ExtensionExtMeshFeatures.h>
+
 BEGIN_DEFINE_SPEC(
     FCesiumPrimitiveFeaturesSpec,
     "Cesium.Unit.PrimitiveFeatures",
@@ -116,6 +119,59 @@ void FCesiumPrimitiveFeaturesSpec::Define() {
     });
   });
 
+  Describe("GetPrimitiveFeatures", [this]() {
+    It("returns for instanced glTF component", [this]() {
+      model = CesiumGltf::Model();
+      model.meshes.emplace_back();
+      CesiumGltf::Node& node = model.nodes.emplace_back();
+      node.mesh = 0;
+
+      CesiumGltf::ExtensionExtInstanceFeatures& instanceFeatures =
+          node.addExtension<CesiumGltf::ExtensionExtInstanceFeatures>();
+      CesiumGltf::ExtensionExtInstanceFeaturesFeatureId& featureId =
+          instanceFeatures.featureIds.emplace_back();
+      featureId.featureCount = 10;
+
+      UCesiumGltfInstancedComponent* pComponent =
+          NewObject<UCesiumGltfInstancedComponent>();
+      pComponent->getPrimitiveData().Features =
+          FCesiumPrimitiveFeatures(model, node, instanceFeatures);
+
+      const FCesiumPrimitiveFeatures& primitiveFeatures =
+          UCesiumPrimitiveFeaturesBlueprintLibrary::GetPrimitiveFeatures(
+              pComponent);
+
+      const TArray<FCesiumFeatureIdSet> featureIDSets =
+          UCesiumPrimitiveFeaturesBlueprintLibrary::GetFeatureIDSets(
+              primitiveFeatures);
+      TestEqual("Number of FeatureIDSets", featureIDSets.Num(), 1);
+    });
+
+    It("gets implicit feature ID", [this]() {
+      model = CesiumGltf::Model();
+      CesiumGltf::Mesh& mesh = model.meshes.emplace_back();
+      pPrimitive = &mesh.primitives.emplace_back();
+      pExtension =
+          &pPrimitive->addExtension<CesiumGltf::ExtensionExtMeshFeatures>();
+      CesiumGltf::FeatureId& featureId = pExtension->featureIds.emplace_back();
+      featureId.featureCount = 10;
+
+      UCesiumGltfPrimitiveComponent* pComponent =
+          NewObject<UCesiumGltfPrimitiveComponent>();
+      pComponent->getPrimitiveData().Features =
+          FCesiumPrimitiveFeatures(model, *pPrimitive, *pExtension);
+
+      const FCesiumPrimitiveFeatures& primitiveFeatures =
+          UCesiumPrimitiveFeaturesBlueprintLibrary::GetPrimitiveFeatures(
+              pComponent);
+
+      const TArray<FCesiumFeatureIdSet> featureIDSets =
+          UCesiumPrimitiveFeaturesBlueprintLibrary::GetFeatureIDSets(
+              primitiveFeatures);
+      TestEqual("Number of FeatureIDSets", featureIDSets.Num(), 1);
+    });
+  });
+
   Describe("GetFeatureIDSetsOfType", [this]() {
     BeforeEach([this]() {
       model = CesiumGltf::Model();

Source/CesiumRuntime/Public/CesiumPrimitiveFeatures.h

@@ -34,8 +34,8 @@ struct CESIUMRUNTIME_API FCesiumPrimitiveFeatures {
   /**
    * Constructs a primitive features instance.
    *
-   * @param Model The model that contains the EXT_mesh_features extension
-   * @param Primitive The mesh primitive that stores EXT_mesh_features
+   * @param Model The model that contains the EXT_mesh_features extension.
+   * @param Primitive The mesh primitive that stores the EXT_mesh_features
    * extension
    * @param Features The EXT_mesh_features of the glTF mesh primitive
    */
@@ -48,9 +48,9 @@ struct CESIUMRUNTIME_API FCesiumPrimitiveFeatures {
    * Constructs an instance feature object.
    *
    * @param Model The model that contains the EXT_instance_features extension
-   * @param Node The node that stores EXT_instance_features
+   * @param Node The node that stores the EXT_instance_features
    * extension
-   * @param InstanceFeatures The EXT_Instance_features of the glTF mesh
+   * @param InstanceFeatures The EXT_instance_features of the glTF mesh
    * primitive
    */
   FCesiumPrimitiveFeatures(