mutateIndexing(sourceIndexBuffers, vertexBuffers, indexBuffer) -> (int, int)
This method gets called to allow the generator to mutate the data for a custom index stream using information stored in the vertex buffers.
* sourceIndexBuffers (MComponentDataIndexingList) - Current values for the index buffers.
* vertexBuffers (MVertexBufferArray) - All vertex buffers generated for this primitive.
* indexBuffer [OUT] (MIndexBuffer) - The index buffer to fill.
Returns the type of primitive of the generated indexing and the stride of the generated indexing, only valid when the returned primitive type is kPatch
See MGeometry.primitiveString() description for a list of valid primitive types.