Add params scene, mesh to function getAttributes

[BlakeOne]

For the class MaterialPluginBase, add params scene and mesh to the function getAttributes so that they can be used to determine which attributes to use.

Forum: https://forum.babylonjs.com/t/using-custom-attribute-with-material-plugin/31142/7

[sebavan]

Just wondering if it should be the mesh or submesh here ?

[BlakeOne]

should be the mesh or submesh here ?

Hmm I assumed it should be the mesh because that's what prepareDefines passes. For me I would just want to be able to check the mesh to see what attributes it has and maybe check properties on it as well. But maybe it would be good to have the subMesh also thou?

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