enderandrew wrote:Understandable, but it is also a chicken and the egg scenario where people may not want to work on bump maps if no engine supports them.
My problem is that I need a realistic setup of textures in order to test how changes to the Doom lighting system will really look. In order to get such an extension accepted by Graf, I have to prove that the extension looks good and is a fitting solution to this particular problem. As he evaluates that just as much by visual testing as by inspection of the code, the test material becomes very important. If the solution does not convince him, it he will reject it based on the fact that a poor solution will just increase code maintenance costs (as he should).
enderandrew wrote:Diffuse, normal and specular maps do rely on directional lighting, but couldn't bump (and maybe displacement) maps be added to create depth on flat walls?
From a technical point of view, what Doom has is only ambient light expressed as a light level. Diffuse and specular light rely on the angle the light source hits the surface of the wall - with just ambient light there is no such thing. The normal map expresses the plane angle of the surface itself, but it has to be paired with the angle the light hits the surface for it to be usable.
Doom had this problem already in 1993 where purely ambient light looks just too flat. The fake contrast feature is actually the faked direction to the light source. There is some chance that this could act as the light source direction for the bump map and specular light as well, but there is also the chance that doing this will reveal to the eye that it's all fake.
I did some tests several months back where I created a fake light direction for the calculations - in some situations that looked very fancy, but in others it looked quite terrible. Part of the reason it varied so much was because I didn't have any specular or normal textures - for some walls that looked excellent for that material, and for others it was a disaster. Had I attempted to PR what I had there, it would most certainly have been rejected on the basis that it violates the Doom light model. Thus, part of the challenge is to prove that such a setup can be shown to work within the boundaries of how light functions in Doom.