[Simplify] How to handle One Vertex Buffer and multiple Indices Buffer

[754978334]

Hello! I want to simplify my mesh, its structure like this:

One Mesh have 1 vertex buffer and n indices buffer. Acutually I use one continous memory and n header info to mark every element's range in indices buffer.

I want to know how to use meshoptimizer to simplify this mesh so I can keep my elements structure! Thanks you!

[zeux]

This is documented at the end of https://meshoptimizer.org/#advanced-simplification. Briefly, you could simplify each subset (element) separately, but that is not quite ideal because the boundaries between elements will either need to be locked, or they will be simplified differently which may leave gaps. You can instead make a big index buffer out of all triangles and simplify the entire index buffer in one call; for you to be able to retrieve the materials again, you need to make sure each unique vertex index has only material - which may require duplicating vertices depending on whether this is already the case or not. As long as different elements refer to different vertices, if the vertex position on the boundary matches, the simplifier will correctly preserve the boundary.

[754978334]

Thanks for your answer! for every vertex, now I have material index, should I pass this parameters as vertex attributes? my attr_weights should be what?
Now I already have 5 vertex attributes, they are normals(Vector3) and UV(Vector2)

[zeux]

No, you don’t need to pass the value as an attribute. The only necessary step is that if any vertex is used by two elements at once, it’s duplicated. The id is useful so that after getting the simplified index buffer, you can split it into elements using the ids stored in vertices

[754978334]

Works for me! Thank you!