If available, use the vertex colors in gltf

[capnm]

PR: #41007
Fixes #21087

This is #41007 for the 3.2 branch. Tested, works as intended.

[fire]

I would reconsider merging this for 3.2. If content has a vertex color the material vertex color would now be on instead of off by default. This is what other gltf importers do. However, this behavior would a large noticeable change.

[capnm]

I would reconsider merging this for 3.2. If content has a vertex color the material vertex color would now be on instead of off by default. This is what other gltf importers do. However, this behavior would a large noticeable change.

I think correctly viewed, this is not an enhancement but a fatal error ;) When you export vertex colors to your glTF file, you probably expect them to be displayed without further ado. Think you have 100 objects where you have to enable an option by hand so that they are displayed correctly. Is a nightmare at least for me.

[akien-mga]

Thanks for the PR, but in such cases it's preferred to use git cherry-pick -x <hash> instead of redoing the commit manually. The former preserves the author information and commit log, and adds a reference to the master commit that is being cherry-picked. This is useful to be able to go back from the cherry-picked commit to the original commit/PR that implemented it, and relevant discussion.

It then looks like this:

commit 13f6efdcc76ce50071e62416049c4673e111e06d (HEAD -> 3.2)
Author:     K. S. Ernest (iFire) Lee <[email protected]>
AuthorDate: Mon Aug 3 11:42:34 2020 -0700
Commit:     Rémi Verschelde <[email protected]>
CommitDate: Tue Sep 29 09:23:10 2020 +0200

    Use the vertex colors by default in gltf.
    
    (cherry picked from commit 43424e132173553201cd26f5aca064ad30e96bda)