All of the examples above assume that geometry is represented as a single vertex buffer and a single index buffer. This requires storing all vertex attributes - position, normal, texture coordinate, skinning weights etc. - in a single contiguous struct. However, in some cases using multiple vertex streams may be preferable. In particular, if some passes require only positional data - such as depth pre-pass or shadow map - then it may be beneficial to split it from the rest of the vertex attributes to make sure the bandwidth use during these passes is optimal. On some mobile GPUs a position-only attribute stream also improves efficiency of tiling algorithms.

Most of the functions in this library either only need the index buffer (such as vertex cache optimization) or only need positional information (such as overdraw optimization). However, several tasks require knowledge about all vertex attributes.

For indexing, meshopt_generateVertexRemap assumes that there's just one vertex stream; when multiple vertex streams are used, it's necessary to use meshopt_generateVertexRemapMulti as follows:

meshopt_Stream streams[] = {
    {&unindexed_pos[0], sizeof(float) * 3, sizeof(float) * 3},
    {&unindexed_nrm[0], sizeof(float) * 3, sizeof(float) * 3},
    {&unindexed_uv[0], sizeof(float) * 2, sizeof(float) * 2},
};

std::vector<unsigned int> remap(index_count);
size_t vertex_count = meshopt_generateVertexRemapMulti(&remap[0], NULL, index_count, index_count, streams, sizeof(streams) / sizeof(streams[0]));

After this meshopt_remapVertexBuffer needs to be called once for each vertex stream to produce the correctly reindexed stream.

Instead of calling meshopt_optimizeVertexFetch for reordering vertices in a single vertex buffer for efficiency, calling meshopt_optimizeVertexFetchRemap and then calling meshopt_remapVertexBuffer for each stream again is recommended.

Finally, when compressing vertex data, meshopt_encodeVertexBuffer should be used on each vertex stream separately - this allows the encoder to best utilize corellation between attribute values for different vertices.