Visual Glitches
In the classic first-person shooter Doom (but less common in newer titles, and completely removed when a skybox is present), an effect known as the 'Hall of Mirrors' can occur as a result of design error or player experimentation.
Games of the day had been programmed under the assumption that the player's viewpoint would always be completely contained within sealed areas.
This made it unnecessary to erase the contents of the screen before drawing the next frame; the new frame would completely cover its predecessor anyway. However, when the player used noclip mode to maneuver the virtual camera so as to violate this assumption, the game would generate frames with "holes" in them where there was no content to display. These frames would fail to completely cover the older ones, leaving whatever had been drawn a moment before still visible in certain regions of the screen. As the player further moved the virtual camera, numerous un-erased regions would blend together to produce visual patterns resembling those encountered in a physical hall of mirrors.
Typing "gl_clear 1" in Quake engine games is a way to empty the buffer of the image of what was last rendered. With this setting, a magenta color is drawn outside of the world, clearing the screen and aiding navigation when outside of the level.
Read more about this topic: Noclip Mode
Famous quotes containing the word visual:
“Unlike any other visual image, a photograph is not a rendering, an imitation or an interpretation of its subject, but actually a trace of it. No painting or drawing, however naturalist, belongs to its subject in the way that a photograph does.”
—John Berger (b. 1926)