Merge pull request #1697 from CesiumGS/default-null-feature

Change default null feature ID to `-1` instead of `0`

Author: kring

CHANGES.md

@@ -1,5 +1,12 @@
 # Change Log {#changes}
 
+### ? - ?
+
+##### Breaking Changes :mega:
+
+- Feature IDs that are encoded by `UCesiumFeaturesMetadataComponent` will now use a default null feature ID of `-1` instead of `0`.
+- Materials generated by `UCesiumFeaturesMetadataComponent` now always check for null feature IDs, assuming a default value of `-1`.
+
 ### v2.16.1 - 2025-06-02
 
 ##### Additions :tada:

Source/CesiumRuntime/Private/CesiumFeaturesMetadataComponent.cpp

@@ -317,10 +317,6 @@ void AutoFillFeatureIdSetDescriptions(
       pDescription->PropertyTableName = getNameForPropertyTable(propertyTable);
     }
 
-    pDescription->bHasNullFeatureId =
-        UCesiumFeatureIdSetBlueprintLibrary::GetNullFeatureID(featureIDSet) >
-        -1;
-
     if (type == ECesiumFeatureIdSetType::Texture) {
       FCesiumFeatureIdTexture featureIdTexture =
           UCesiumFeatureIdSetBlueprintLibrary::GetAsFeatureIDTexture(
@@ -1362,7 +1358,7 @@ void GenerateNodesForNullFeatureId(
   UMaterialExpressionScalarParameter* NullFeatureId =
       NewObject<UMaterialExpressionScalarParameter>(TargetMaterialLayer);
   NullFeatureId->ParameterName = FName(SafeName + MaterialNullFeatureIdSuffix);
-  NullFeatureId->DefaultValue = 0;
+  NullFeatureId->DefaultValue = -1.0f;
   NullFeatureId->MaterialExpressionEditorX = NodeX;
   NullFeatureId->MaterialExpressionEditorY = NodeY;
   AutoGeneratedNodes.Add(NullFeatureId);
@@ -2349,23 +2345,23 @@ void GenerateMaterialNodes(
       }
     }
 
-    if (featureIdSet.bHasNullFeatureId) {
-      // Spatial nitpicking; this aligns the if statement to the same Y as the
-      // PropertyTableFunction node then resets the Y so that the next section
-      // appears below all of the just-generated nodes.
-      int32 OriginalY = NodeY;
-      NodeY = BeginSectionY;
+    // Spatial nitpicking; this aligns the if statement to the same Y as the
+    // PropertyTableFunction node then resets the Y so that the next section
+    // appears below all of the just-generated nodes.
+    int32 OriginalY = NodeY;
+    NodeY = BeginSectionY;
 
-      GenerateNodesForNullFeatureId(
-          featureIdSet,
-          MaterialState.AutoGeneratedNodes,
-          pComponent->TargetMaterialLayer,
-          NodeX,
-          NodeY,
-          LastNode);
+    // Even if a feature ID set doesn't specify a `nullFeatureId`, we use -1
+    // as the default.
+    GenerateNodesForNullFeatureId(
+        featureIdSet,
+        MaterialState.AutoGeneratedNodes,
+        pComponent->TargetMaterialLayer,
+        NodeX,
+        NodeY,
+        LastNode);
 
-      NodeY = OriginalY;
-    }
+    NodeY = OriginalY;
     MaximumSectionX = FMath::Max(MaximumSectionX, NodeX);
 
     NodeX = BeginSectionX;

Source/CesiumRuntime/Private/CesiumGltfComponent.cpp

@@ -390,7 +390,7 @@ void copyFeatureIds(
       vertices.SetVertexUV(
           i,
           textureCoordinateIndex,
-          FVector2f(glm::max(featureId, 0.0f), 0.0f));
+          FVector2f(featureId, 0.0f));
     }
   } else {
     for (int64_t i = 0; i < vertices.GetNumVertices(); ++i) {
@@ -400,7 +400,7 @@ void copyFeatureIds(
       vertices.SetVertexUV(
           i,
           textureCoordinateIndex,
-          FVector2f(glm::max(featureId, 0.0f), 0.0f));
+          FVector2f(featureId, 0.0f));
     }
   }
 }

Source/CesiumRuntime/Public/CesiumFeaturesMetadataDescription.h

@@ -68,15 +68,6 @@ struct CESIUMRUNTIME_API FCesiumFeatureIdSetDescription {
    */
   UPROPERTY(EditAnywhere, Category = "Cesium")
   FString PropertyTableName;
-
-  /**
-   * The null feature ID for the feature ID set. This value indicates that no
-   * feature is associated with the vertex or texel containing the value. If no
-   * such value is specified, this defaults to -1, which prevents it from being
-   * unnecessarily included in the generated material.
-   */
-  UPROPERTY(EditAnywhere, Category = "Cesium")
-  bool bHasNullFeatureId = false;
 };
 
 /**