Color Map (Vehicle)

A color map, also incorrectly referred to as a diffuse map, is a texture used for the color and look of an object. This map is what gives a 3D model its distinct characteristics and visual interest.

Components of a Color Map
A vehicle's color map has two distinct parts, each with different specifications:
 * Color channels (RGB)
 * Transparency (Alpha)

These channels make up the base texture of a 3D vehicle model. It must be UV mapped to a vehicle's surface.

Color Channels (RGB)
The color channels are used for mapping color onto an object. This is where all of the designs, decals, images and color are stored. For vehicles, everything from your headlights to the rims on your car are part of the color map. The color map should normally take the most time to create out of the four primary textures for a vehicle. This is due to the amount of design and detail usually incorporated into the texture to give the object a realistic look.

While a color map is normally depicted as 'true color', leaving the rendering engine to generate lighting and shadows, it is good practice to include basic shading on your color map. SimCity's graphics engine does not focus on small lighting details at a vehicle level, so giving your models slight definition in shading and highlights will improve the overall look of your model. Use these shading details in conjunction with the gloss map and  normal map to achieve realistic results.

Transparency (Alpha)
An alpha channel is used in relation to the color palette, which allows random colors to be generated for a vehicle. Any transparent areas of the texture, indicated by the alpha channel, will cause a randomly generated color to appear underneath the base color map.

As part of the SimCityPak and DXT5 file type restrictions, an alpha channel is required on any imported texture. This does not mean that your texture needs transparency; an alpha channel can be blank, rendering your texture with a solid fill. The Nvidia DDS Plugin will automatically generate a filled alpha channel upon export of a DXT5 file.