implementation model supports index buffers but there is no way to provide it with user-defined data.
index buffer support provides an opportunity to optimize vertex data.
add an index buffer member to vertex_data object. Should be optional, could be done via a default value since models will not generate an ibo if the provided index array is length 0.
add an index buffer member to vertex_data object. Should be optional, could be done via a default value since models will not generate an ibo if the provided index array is length 0.