.dds is short for Direct Draw Surface. The .dds extension is the file format for all texures used in game, altough sometimes you can find leftover .tga files. .dds Files can be edited with various DDS Editor, of which DXTBmp is the best and easiest to use, as well as plug-ins for several graphic suites, e.g. Photoshop.
.dds textures in Zoo Tycoon 2 are saved as the following 4 .dds types:
- DDS DXT1
- DDS DXT3
- 565 16 bit
- DDS 888 24 bit
- DXT1 is used to save .dds files so that there is no alpha. This is commonly used for bark, walls, and rocks.
- DXT3 is used to preserve transparency and alphas. This is used for animals, trees, and plants.Also, in some cases icons can be saved in this format.
- 16 bit is used for the default file type for icons.
- 24 bit is used for ground textures such as grass cover or dirt.
You can also use mip maps for skins. But you have to disable them on icons.