• "Besides godot gives me a lot of useful stuff." If it's not even allowing you to use basic aspects of a shader like gl_VertexID, then I would seriously contest that statement. I'm fairly sure that other engines can provide whatever "lot of useful stuff" that Godot does without Godot's pointless limitations. For example, my suggestion would be to use a buffer texture or an SSBO for such "attributes", but given that it doesn't even allow you to use gl_VertexID, I would be surprised if it let you use those features. – Nicol Bolas Feb 8 at 18:28
• The problem is that I don't know what Godot will allow you to do, so I can't advise you. For example, I know how to make the texture-based idea work in a way that offers most if not all of the features of a vertex attribute. But I don't know if Godot will actually let you do those things needed to make it work. Again, if it's not letting you touch basic OpenGL functionality like gl_VertexID, who knows? Does it allow you to use floating-point image formats? What about integer textures? What about the GLSL functions for doing integer normalization? What about texelFetch? Etc. – Nicol Bolas Feb 8 at 18:47