mesh simplify with attributes, how to handle independent index on position/uv

[754978334]

Hello! I want use meshopt_simplifyWithAttributes to simplify my obj file, which triangle like

f x/x/x means position index/ normal index / uv index
I find that the the position and uv have independent index. But parameters of meshopt_simplifyWithAttributes seems like position and uv have same index.
I want to know whether I need to do some preprocess on my model data. Such like turn [data+index form] to [x1, y1, z1, x2, y2, z2 ... form]. Is there any code that I can use as a reference?
I am a beginner of mesh processing so my question maybe seems silly. Thanks for you all!

[zeux]

meshoptimizer works with "graphics ready" meshes, which basically implies the existence of a vertex buffer and a single index buffer. For formats that specify the data in some other way you typically need to build an unindexed mesh and then reindex it, see https://meshoptimizer.org/#indexing. You can see examples of doing so in this repository, such as https://github.com/zeux/meshoptimizer/blob/master/demo/main.cpp#L68-L145