Overview

This is the texture representing the specular intensity and color of material highlights defined as the "shininess" and color of specular reflections.

In most cases this is a modified black and white diffuse merged with perhaps different rendered maps such as cavity maps to achieve a desired look.

Some notes to keep in mind which often determine a good specular texture are:

• High contrast, variations between black and white are easily visible.
• White is absolute specularity/reflectivity while black is no reflection whatsoever.
• Artists often use the specular to help exaggerate definitions with the other maps to make details more visible.

Choosing how to utilize your specular map

CryENGINE computes specular by using P and M:

• Power of specular (controls how hard/strong/blurry reflection is).
• Multiplier (or scaler) for computed specular (0-1 range, from "no specular" to "normal specular" output). I call it "anti-dirtyness".

Presets and material settings used dictate from where those P and M come.

Below are three options:

1. Specular data is in the alpha channel of the diffuse image.
Requires "gloss map in diff alpha" enabled in material.
Image uses preset DiffusewithAlpha_XXX, alpha channel contains M.
Image produces single texture, DXT5 format.
P comes from material settings (called glossiness level or so), so it's same P for every texel.

2. Specular data is in a separate image (no alpha channel), diffuse image has no alpha channel.
First image uses preset Diffuse_xxxx, second image uses Specular_xxxx (color channels contain M).
First image produces DXT1 texture, second one produces DXT1 texture. Total size of those two textures is same as size of single texture in option #1.
P comes from material settings (called glossiness level or so), so it's same P value for every texel.
Note that comparing to option #1, you have per-color-channel M, so you can control how much of each of R/G/B is reflected per-pixel.

3. Specular data is in a separate image (should have alpha channel), diffuse image has no alpha channel.
First image uses preset Diffuse_xxxx, second image uses Specular_xxxx (color channels contain M same as in option #2; alpha contains multiplier for P, see below).
First image produces DXT1 texture, second one produces DXT5 texture. Total size of textures is 50% bigger than size in options #1 and #2.
P comes from material settings (called glossiness level or so) multiplied by values from alpha channel of the second image, so it's per-texel. So, you can control hardness of specular on per-texel level.
Same as in #2 you can control how much of each of R/G/B is reflected per-pixel.

Note that if you are tight on memory and you don't care about having high-precision specular, then sometimes it's better to use #2 instead of #1, because it will allow you to use different resolutions for diffuse and specular textures. For example your diffuse texture is 1024x1024 and specular texture is 256x256.