@perna: well no, it represents how tinted the specular color is by the diffuse. i interpolate between white and the diffuse color, based on this tint value. so mix(white, diffuse, tint).
I gotta agree with r_fletch_r here, most metals do have low diffuse reflectance and higher specular reflectance, but saying that metals have no diffuse reflectance is incorrect. I mean look at a metal like Copper, it always has that brownish/orangery colour that comes from it's diffuse reflectance value. If you had a…
The main reason for using color or not is to accurately represent the given material, like r_fletch_r mentioned. There is a small benefit to grayscale spec maps though. You can store them in a channel of your diffuse map when importing into a game engine to conserve texture memory.
this is the biggest falsity ever perpetrated. the only way using the alpha channel for spec maps will help is to cut down on texture calls in a material, as you will only call a single texture sample for both diffuse and specular. a DXT5 texture (RGB+A) takes up the same amount of memory as two DXT1 textures (RGB).
there's one historical reason and one physical reason to use colored specular. On one hand using the inverse of the diffuse color is an acceptable way to combat gamma incorrect shader pipelines. But that reason sucks and i'll have none of it. The other, "proper" as you call it, way of using colored specular maps relates to…
Nothing personal mate but this is totally and utterly wrong. Metals dont absorb all light that enters them, they simply tend to be quite smooth and dont diffuse the light which hits them. If they absorbed all light they would be black. I know im being picky here and you had the basic idea right so far as shader balancing…
study your materials really really well and USE ALL THE MAPS AT THE SAME TIME. often if you make your spec after your diffuse, your spec will just turn into an afterthought. you must work with the all your maps at the same time to realistically portray an active, dynamic looking material. as far as i know, with DXT alphas…