Lighting

What sets Doom 64 apart from other Doom games is its lighting system. In general lighting is defined at the sector-level. Then from here there are two types of lighting in Doom 64: gradient lighting and additive lighting.

Doom 64's gradient lighting is based upon gouraud shading. Here color gradients are defined across polygon vertices and are multiplied against the textures. This allows the brightness along walls to be changed and texture color to be changed. Since it is color multiplicative process, the output ends up being darkened. Thus this is the root cause for Doom 64's notorious darkness. The page below describes gradient lighting in more detail.

• Gradient Lighting

The second kind of lighting is additive lighting. As opposed to multiplicative lighting, greyscale color is added to the texture, thus brightening the texture. This lighting is animated in Doom 64 and results in the flickering, glowing, and strobing light effects in the game. The page below describes additive lighting in more detail.

• Additive Lighting