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the_ether
11-07-2001, 10:57 AM
What are the different techniques for making something appear to move?

- changes to the x,y,z co-ords of a mesh with transformation
- translation of a decal
- distortion of the mesh
- animation through cycling of textures
- ...?

MikeC
11-07-2001, 02:59 PM
Unanswerably vague question.

Changes to pretty much anything can be used to give the appearance of some sort of movement if you set things up right. That means any of the matrices (modelview, projection, texture, even color at a pinch), any vertex components (position, normal, color, texcoord), viewport, scissor box, texture images, texture palettes, blend/depthtest/stencil ops etc etc. And that's just unextended GL; never mind the zillion flavours of vertex programming.

Basically, anything you can think of, and you'll still miss some. (I remember some of the early Doom clones on the Amiga; because pixel-plotting is dog slow on a planar framebuffer, they used to clear the whole screen to the same color and then used the display coprocessor to poke a new color value into that hardware palette entry for each pixel during scanout...)