The tutti-frutti effect is a texture effect which can appear on walls. The texture is rendered distorted and there are often colors drawn which are not part of the original texture. These colors are the reason behind the name of the effect.
Tutti-frutti can be caused in several ways:
- If a wall is taller than its texture, then the texture is tiled vertically. But the Doom rendering engine starts new tiles only at heights of 128, 256, 384, etc. If the texture is less than 128 units tall, horizontal bands will be left undefined.
- If a texture with transparent areas is used as an upper or lower texture on a two-sided wall, the content of the transparent areas is undefined. (By definition, the player can see the sector behind a wall only through the middle.)
- If a texture with transparent areas is used as the texture on a one-sided wall, the content of the transparent areas is undefined.
In E2M2: Containment Area there is a particular door with the tech wires texture, which has a horizontal green stripe supposed to mark it. That stripe is caused by the tutti-frutti effect.
E2M7: Spawning Vats contains an example of the tutti-frutti effect. One area contains a door consisting of two sectors; by blocking one sector from closing, it is possible to reveal a non-tiling texture which triggers the effect (see demo below).
The tutti-frutti effect was officially fixed in the Atari Jaguar port of Doom.