2 files changed, 10 insertions, 16 deletions

diff --git a/indra/llmath/llvolume.cpp b/indra/llmath/llvolume.cpp
index ae753fc0f3..559d790d77 100644
--- a/indra/llmath/llvolume.cpp
+++ b/indra/llmath/llvolume.cpp
@@ -2783,7 +2783,7 @@ bool LLVolume::unpackVolumeFaces(std::istream& is, S32 size)
 		}
 	}
 
-	if (!cacheOptimize())
+	if (!cacheOptimize(true))
 	{
 		// Out of memory?
 		LL_WARNS() << "Failed to optimize!" << LL_ENDL;
@@ -2824,11 +2824,11 @@ void LLVolume::copyVolumeFaces(const LLVolume* volume)
 	mSculptLevel = 0;
 }
 
-bool LLVolume::cacheOptimize()
+bool LLVolume::cacheOptimize(bool gen_tangents)
 {
 	for (S32 i = 0; i < mVolumeFaces.size(); ++i)
 	{
-		if (!mVolumeFaces[i].cacheOptimize())
+		if (!mVolumeFaces[i].cacheOptimize(gen_tangents))
 		{
 			return false;
 		}
@@ -5478,18 +5478,13 @@ struct MikktData
 };
 
 
-bool LLVolumeFace::cacheOptimize()
+bool LLVolumeFace::cacheOptimize(bool gen_tangents)
 { //optimize for vertex cache according to Forsyth method: 
     LL_PROFILE_ZONE_SCOPED_CATEGORY_VOLUME;
 	llassert(!mOptimized);
 	mOptimized = TRUE;
 
-    if (!mNormals || !mTexCoords)
-    { // can't perform this operation without normals and texture coordinates
-        return false;
-    }
-
-    if (mMikktSpaceTangents == nullptr)
+    if (mMikktSpaceTangents == nullptr && gen_tangents && mNormals && mTexCoords)
     { // make sure to generate mikkt space tangents for cache optimizing since the index buffer may change
         allocateTangents(mNumVertices, true);
 
diff --git a/indra/llmath/llvolume.h b/indra/llmath/llvolume.h
index e373d0175d..6ea12c6920 100644
--- a/indra/llmath/llvolume.h
+++ b/indra/llmath/llvolume.h
@@ -907,7 +907,7 @@ public:
     void remap();
 
 	void optimize(F32 angle_cutoff = 2.f);
-	bool cacheOptimize();
+	bool cacheOptimize(bool gen_tangents = false);
 
 	void createOctree(F32 scaler = 0.25f, const LLVector4a& center = LLVector4a(0,0,0), const LLVector4a& size = LLVector4a(0.5f,0.5f,0.5f));
 
@@ -957,10 +957,6 @@ public:
     // indexes for mPositions/mNormals/mTexCoords
 	U16* mIndices;
 
-	// vertex buffer filled in by LLFace to cache this volume face geometry in vram 
-	// (declared as a LLPointer to LLRefCount to avoid dependency on LLVertexBuffer)
-	mutable LLPointer<LLRefCount> mVertexBuffer; 
-
 	std::vector<S32>	mEdge;
 
 	//list of skin weights for rigged volumes
@@ -1089,7 +1085,10 @@ public:
 	void copyVolumeFaces(const LLVolume* volume);
 	void copyFacesTo(std::vector<LLVolumeFace> &faces) const;
 	void copyFacesFrom(const std::vector<LLVolumeFace> &faces);
-	bool cacheOptimize();
+
+    // use meshoptimizer to optimize index buffer for vertex shader cache
+    //  gen_tangents - if true, generate MikkTSpace tangents if needed before optimizing index buffer
+	bool cacheOptimize(bool gen_tangents = false);
 
 private:
 	void sculptGenerateMapVertices(U16 sculpt_width, U16 sculpt_height, S8 sculpt_components, const U8* sculpt_data, U8 sculpt_type);