From 933c3e387172f69474551d8d27cf3c27fd5e807a Mon Sep 17 00:00:00 2001
From: keyboardspecialist <jason.sobotka@cesium.com>
Date: Fri, 24 Jan 2025 12:05:48 -0600
Subject: [PATCH] added splat indexes to vertex attributes updates geometry
 pipeline stage to use modelutility to find attributes

---
 .../Scene/Model/GeometryPipelineStage.js      | 29 ++++++++++++-------
 .../Source/Scene/VertexAttributeSemantic.js   | 14 +++++++++
 2 files changed, 33 insertions(+), 10 deletions(-)

diff --git a/packages/engine/Source/Scene/Model/GeometryPipelineStage.js b/packages/engine/Source/Scene/Model/GeometryPipelineStage.js
index 300b1c4669a4..fd503f71dcad 100644
--- a/packages/engine/Source/Scene/Model/GeometryPipelineStage.js
+++ b/packages/engine/Source/Scene/Model/GeometryPipelineStage.js
@@ -143,18 +143,27 @@ GeometryPipelineStage.process = function (
       model?.style?.showGaussianSplatting ?? model.showGaussianSplatting;
 
     if (gaussianSplatsEnabled === true) {
-      primitive.attributes.find((a) => a.name === "POSITION").instanceDivisor =
-        showSplats ? 1 : 0;
-      primitive.attributes.find((a) => a.name === "_SCALE").instanceDivisor =
-        showSplats ? 1 : 0;
-      primitive.attributes.find((a) => a.name === "_ROTATION").instanceDivisor =
-        showSplats ? 1 : 0;
-      primitive.attributes.find((a) => a.name === "COLOR_0").instanceDivisor =
-        showSplats ? 1 : 0;
+      ModelUtility.getAttributeBySemantic(
+        primitive,
+        VertexAttributeSemantic.POSITION,
+      ).instanceDivisor = showSplats ? 1 : 0;
+      ModelUtility.getAttributeBySemantic(
+        primitive,
+        VertexAttributeSemantic.SCALE,
+      ).instanceDivisor = showSplats ? 1 : 0;
+      ModelUtility.getAttributeBySemantic(
+        primitive,
+        VertexAttributeSemantic.ROTATION,
+      ).instanceDivisor = showSplats ? 1 : 0;
+      ModelUtility.getAttributeBySemantic(
+        primitive,
+        VertexAttributeSemantic.COLOR,
+      ).instanceDivisor = showSplats ? 1 : 0;
 
       if (primitive.hasGaussianSplatTexture) {
-        primitive.attributes.find(
-          (a) => a.name === "_SPLAT_INDEXES",
+        ModelUtility.getAttributeBySemantic(
+          primitive,
+          VertexAttributeSemantic.SPLAT_INDEXES,
         ).instanceDivisor = showSplats ? 1 : 0;
       }
 
diff --git a/packages/engine/Source/Scene/VertexAttributeSemantic.js b/packages/engine/Source/Scene/VertexAttributeSemantic.js
index 0225bf5d3fba..db3cb3e39252 100644
--- a/packages/engine/Source/Scene/VertexAttributeSemantic.js
+++ b/packages/engine/Source/Scene/VertexAttributeSemantic.js
@@ -87,6 +87,13 @@ const VertexAttributeSemantic = {
    * @constant
    */
   ROTATION: "_ROTATION",
+  /**
+   * Gaussian Splat Attribute Texture Index
+   *
+   * @type {string}
+   * @constant
+   */
+  SPLAT_INDEXES: "_SPLAT_INDEXES",
 };
 
 function semanticToVariableName(semantic) {
@@ -111,6 +118,8 @@ function semanticToVariableName(semantic) {
       return "scale";
     case VertexAttributeSemantic.ROTATION:
       return "rotation";
+    case VertexAttributeSemantic.SPLAT_INDEXES:
+      return "splatIndex";
     //>>includeStart('debug', pragmas.debug);
     default:
       throw new DeveloperError("semantic is not a valid value.");
@@ -144,6 +153,7 @@ VertexAttributeSemantic.hasSetIndex = function (semantic) {
     case VertexAttributeSemantic.FEATURE_ID:
     case VertexAttributeSemantic.SCALE:
     case VertexAttributeSemantic.ROTATION:
+    case VertexAttributeSemantic.SPLAT_INDEXES:
       return true;
     //>>includeStart('debug', pragmas.debug);
     default:
@@ -196,6 +206,8 @@ VertexAttributeSemantic.fromGltfSemantic = function (gltfSemantic) {
       return VertexAttributeSemantic.SCALE;
     case "_ROTATION":
       return VertexAttributeSemantic.ROTATION;
+    case "_SPLAT_INDEXES":
+      return VertexAttributeSemantic.SPLAT_INDEXES;
   }
 
   return undefined;
@@ -269,6 +281,8 @@ VertexAttributeSemantic.getGlslType = function (semantic) {
       return "vec3";
     case VertexAttributeSemantic.ROTATION:
       return "vec4";
+    case VertexAttributeSemantic.SPLAT_INDEXES:
+      return "int";
     //>>includeStart('debug', pragmas.debug);
     default:
       throw new DeveloperError("semantic is not a valid value.");