Rassilon wrote:LOL well suppose I could start using that but will it really make a difference relitive to size? png or 2 jpg files....I'll look into it I suppose
It can . . . But if you use two png or jpg files--one for specular and one for color--you'll end up using twice as much texture memory as if you combine them in a single texture. However, you can usually get away with using a half-resolution texture for specular. The big win with separate specular textures is when you're using compressed textures. With a combined spec/color texture, you have to use DXT5, which is twice the size of a DXT1 texture. With separate textures, you can use DXT1 for both. There's no advantage if they're the same size, but if you use a half res spec texture, you'll use 37.5% less texture memory . . .
It works like this (and I'll ignore mipmaps for these calculations)
Let's say you have an 8k x 4k texture . . .
Uncompressed color map:
8k x 4k x 32bpp = 128 M
Uncompressed color+spec map - same as color only - 128 M
Uncompressed spec map:
8k x 4k x (32 or 8 bpp) = 128 or 32 M (depends on if your graphics card supports luminance textures)
Uncompressed half res spec map:
4k x 2k x (32 or 8 bpp) = 32 or 8 M
DXT1 color map:
8k x 4k x 4bpp = 16 M
DXT1 spec map - same as DXT1 color map - 16 M
DXT1 half res spec map:
4k x 2k x 4bpp = 4 M
DXT5 color+spec:
8k x 4k x 8bpp = 32 M
Uncompressed 8k x 4k uses 128 M, which is not going to happen on any current consumer graphics hardware.
DXT5 color+spec is 32 M total
DXT1 color + DXT1 spec uses 16 M for color and 16 M for spec, or 32 M total
DXT1 color + DXT1 half res spec uses 16 M for color and 4 M for spec, or 20 M total
The main reason that I added support for separate specular maps is for the DXT1 color + DXT1 half res specular case. It's an excellent way to save a lot of texture memory on your planets that need specular highlights. Also, if the entire planet is reflective (e.g. an ocean planet), you can omit the specular texture completely.
--Chris