Specular

Gives you per-pixel control over the color and intensity of specular highlights anywhere on the map. You could eg. make all highlights red, or have them depend on the type of material that a pixel represents, or something more exotic. The alpha channel defines how "polished" the surface looks (glossiness), and the RGB color is the amount of light that gets reflected for each color channel.

Example Specular Texture	Ingame Result
File:Mapdev-specular.jpg	File:Mapdev-spec with.jpg

Specification

mapinfo.lua

The relevant sections of the mapinfo.lua

If specularTex points to a file that does not exist, you will get full unmoderated specularity based on whatever your map's lighting settings are

local mapinfo = {
   resources = {
      ...
      specularTex = "",
      ...
   },
   ...
   lighting = {
      ...
      groundSpecularColor = {0.1, 0.1, 0.1},
      ...
   },
   ...
}

Image File

File Location	./maps/
File Format	PNG, TGA
Colour Depth	8bpp
Channels	RGBA
Resolution	Any, recommended powers of two, will be stretched over the terrain.

The RGB channels will control the red, green, and blue contribution per highlight
The Alpha channel (multiplied by 16) becomes the specular exponent. Or on other words controls the sharpness of the specular highlights, the higher the value the sharper the highlights.
You have to set the RGB values to zero if you want no specular contribution
If you omit the alpha channel, or have a fully opaque image, the specular exponent is at its max and the results are a very sharp specular highlights.

File:Mapdev-spec alpha issue.jpg

Forum Discussion

Make Your Maps Shiny(er) With SSMF