Use more material information

[Mick van Gelderen]

I want to have a

• diffuse map
• specular map
• bump map
• mask map

for every material.

• Need to maintain a map from texture file path to texture to deduplicate texture loading.
• Need to create artificial 1x1 maps for materials that use a constant.

Unsolved

Alpha channel vs separate mask?
Have extra uniforms to decide whether to sample from a texture or use a uniform value? Or just create a texture for everything?