Store material as vertex attribute

Question

I'm rendering multiple objects with multiple material. Usually material is represented as uniform in shader, and to render the whole scene we call draw for each material.

Can I represent material (Kd, Ka etc) as vertex attribute and send it to fragment shader with flat interpolation? This way we can draw with just a single command. What is the disadvantage of this approach?

Answer 1

You can definitely do this; simply define the material as a vertex attribute just as you would for color, normal, or position. I wouldn't worry too much about sending 2 extra floats (diffuse, ambient) per vertex to a modern graphics card. There might be a slight performance difference, but not much. If this is what you need, then using a vertex attribute is the cleanest approach.