Don't duplicate vertices for unlit meshes.

CesiumGS · Oct 2, 2024 · eee0450 · eee0450
1 parent 5e326af
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diff --git a/CHANGES.md b/CHANGES.md
@@ -9,6 +9,7 @@
 ##### Fixes :wrench:
 
 - Fixed a bug that caused incorrect lighting for tilesets using `KHR_materials_unlit`.
+- Reduced the memory used by tiles with `KHR_materials_unlit`.
 - `CesiumGlobeAnchor` properties are no longer shown on the main `CesiumSunSky` Details panel, because it is almost never necessary to set these. They can still be set on the component's own Details panel if needed.
 
 ### v2.9.0 - 2024-10-01

diff --git a/Source/CesiumRuntime/Private/CesiumGltfComponent.cpp b/Source/CesiumRuntime/Private/CesiumGltfComponent.cpp
@@ -1367,7 +1367,10 @@ static void loadPrimitive(
   // vertices shared by multiple triangles. If we don't have tangents, but
   // need them, we need to use a tangent space generation algorithm which
   // requires duplicated vertices.
-  bool duplicateVertices = !hasNormals || (needsTangents && !hasTangents);
+  bool normalsAreRequired = !primitiveResult.isUnlit;
+  bool needToGenerateFlatNormals = normalsAreRequired && !hasNormals;
+  bool needToGenerateTangents = needsTangents && !hasTangents;
+  bool duplicateVertices = needToGenerateFlatNormals || needToGenerateTangents;
   duplicateVertices =
       duplicateVertices && primitive.mode != MeshPrimitive::Mode::POINTS;