Add Function ColladaParser::ReadPrimTriStrips.

This does the index mangling for reading tristrips.

code/ColladaParser.cpp

@@ -2122,6 +2122,10 @@ void ColladaParser::ReadPrimitives( Mesh* pMesh, std::vector<InputChannel>& pPer
 				for (size_t currentVertex = 0; currentVertex < numPoints; currentVertex++)
 					CopyPrimitive(currentVertex, numOffsets, numPoints, perVertexOffset, pMesh, pPerIndexChannels, currentPrimitive, indices);
 				break;
+			case Prim_TriStrips:
+				numPoints = 3;
+				ReadPrimTriStrips(numOffsets, perVertexOffset, pMesh, pPerIndexChannels, currentPrimitive, indices);
+				break;
 			case Prim_Polylist: 
 				numPoints = pVCount[currentPrimitive];
 				for (size_t currentVertex = 0; currentVertex < numPoints; currentVertex++)
@@ -2134,7 +2138,7 @@ void ColladaParser::ReadPrimitives( Mesh* pMesh, std::vector<InputChannel>& pPer
 					CopyPrimitive(currentVertex, numOffsets, numPoints, perVertexOffset, pMesh, pPerIndexChannels, currentPrimitive, indices);
 				break;
 			default:
-				// LineStrip and TriStrip not supported due to expected index unmangling
+				// LineStrip is not supported due to expected index unmangling
 				ThrowException( "Unsupported primitive type.");
 				break;
 		}
@@ -2171,6 +2175,20 @@ void ColladaParser::CopyPrimitive(size_t currentVertex, size_t numOffsets, size_
 	pMesh->mFacePosIndices.push_back(vindex[perVertexOffset]);
 }
 
+void ColladaParser::ReadPrimTriStrips(size_t numOffsets, size_t perVertexOffset, Mesh* pMesh, std::vector<InputChannel>& pPerIndexChannels, size_t currentPrimitive, const std::vector<size_t>& indices){
+	if (currentPrimitive % 2 != 0){
+		//odd tristrip triangles need their indices mangled, to preserve winding direction
+		CopyPrimitive(1, numOffsets, 1, perVertexOffset, pMesh, pPerIndexChannels, currentPrimitive, indices);
+		CopyPrimitive(0, numOffsets, 1, perVertexOffset, pMesh, pPerIndexChannels, currentPrimitive, indices);
+		CopyPrimitive(2, numOffsets, 1, perVertexOffset, pMesh, pPerIndexChannels, currentPrimitive, indices);
+	}
+	else {//for non tristrips or even tristrip triangles
+		CopyPrimitive(0, numOffsets, 1, perVertexOffset, pMesh, pPerIndexChannels, currentPrimitive, indices);
+		CopyPrimitive(1, numOffsets, 1, perVertexOffset, pMesh, pPerIndexChannels, currentPrimitive, indices);
+		CopyPrimitive(2, numOffsets, 1, perVertexOffset, pMesh, pPerIndexChannels, currentPrimitive, indices);
+	}
+}
+
 // ------------------------------------------------------------------------------------------------
 // Extracts a single object from an input channel and stores it in the appropriate mesh data array 
 void ColladaParser::ExtractDataObjectFromChannel( const InputChannel& pInput, size_t pLocalIndex, Mesh* pMesh)

code/ColladaParser.h

@@ -185,6 +185,10 @@ protected:
 		Collada::Mesh* pMesh, std::vector<Collada::InputChannel>& pPerIndexChannels,
 		size_t currentPrimitive, const std::vector<size_t>& indices);
 
+	/** Reads one triangle of a tristrip into the mesh */
+	void ReadPrimTriStrips(size_t numOffsets, size_t perVertexOffset, Collada::Mesh* pMesh,
+		std::vector<Collada::InputChannel>& pPerIndexChannels, size_t currentPrimitive, const std::vector<size_t>& indices);
+
 	/** Extracts a single object from an input channel and stores it in the appropriate mesh data array */
 	void ExtractDataObjectFromChannel( const Collada::InputChannel& pInput, size_t pLocalIndex, Collada::Mesh* pMesh);