From 948556133829386dbc54b7830d65916894377ae1 Mon Sep 17 00:00:00 2001
From: Kevin Ring <kevin@kotachrome.com>
Date: Tue, 24 Dec 2024 15:08:24 +1100
Subject: [PATCH] Add a little explanation of the index being a vertex or
 instance index.

---
 .../CesiumRuntime/Private/CesiumFeatureIdAttribute.cpp |  4 ++--
 Source/CesiumRuntime/Public/CesiumFeatureIdAttribute.h | 10 +++++++++-
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/Source/CesiumRuntime/Private/CesiumFeatureIdAttribute.cpp b/Source/CesiumRuntime/Private/CesiumFeatureIdAttribute.cpp
index f1d7c5eec..60936b34e 100644
--- a/Source/CesiumRuntime/Private/CesiumFeatureIdAttribute.cpp
+++ b/Source/CesiumRuntime/Private/CesiumFeatureIdAttribute.cpp
@@ -82,8 +82,8 @@ int64 UCesiumFeatureIdAttributeBlueprintLibrary::GetCount(
 
 int64 UCesiumFeatureIdAttributeBlueprintLibrary::GetFeatureID(
     UPARAM(ref) const FCesiumFeatureIdAttribute& FeatureIDAttribute,
-    int64 VertexIndex) {
+    int64 Index) {
   return std::visit(
-      CesiumGltf::FeatureIdFromAccessor{VertexIndex},
+      CesiumGltf::FeatureIdFromAccessor{Index},
       FeatureIDAttribute._featureIdAccessor);
 }
diff --git a/Source/CesiumRuntime/Public/CesiumFeatureIdAttribute.h b/Source/CesiumRuntime/Public/CesiumFeatureIdAttribute.h
index 875914efe..7604a1239 100644
--- a/Source/CesiumRuntime/Public/CesiumFeatureIdAttribute.h
+++ b/Source/CesiumRuntime/Public/CesiumFeatureIdAttribute.h
@@ -29,7 +29,8 @@ enum class ECesiumFeatureIdAttributeStatus : uint8 {
 /**
  * @brief A blueprint-accessible wrapper for a feature ID attribute from a glTF
  * model. Provides access to feature IDs which can be used with the
- * corresponding {@link FCesiumPropertyTable} to access metadata.
+ * corresponding {@link FCesiumPropertyTable} to access metadata. These feature
+ * IDs may be defined per-vertex or per-instance.
  */
 USTRUCT(BlueprintType)
 struct CESIUMRUNTIME_API FCesiumFeatureIdAttribute {
@@ -133,6 +134,9 @@ class CESIUMRUNTIME_API UCesiumFeatureIdAttributeBlueprintLibrary
    * Gets the number of elements in the attribute. This is distinct from the
    * number of unique feature IDs within the attribute.
    *
+   * For a feature ID attribute of a regular mesh, this is the number of
+   * vertices. For a per-instance feature ID, this is the number of instances.
+   *
    * If the feature ID attribute is invalid, this returns 0.
    */
   UFUNCTION(
@@ -146,6 +150,10 @@ class CESIUMRUNTIME_API UCesiumFeatureIdAttributeBlueprintLibrary
    * Gets the feature ID at the given index. A feature ID can be used with a
    * FCesiumPropertyTable to retrieve the metadata for that ID. If the feature
    * ID attribute is invalid, this returns -1.
+   *
+   * For a feature ID attribute of a regular mesh, the provided Index is the
+   * index of a vertex within the mesh. For a per-instance feature ID, the
+   * provided Index is the index of the instance.
    */
   UFUNCTION(
       BlueprintCallable,