CompuServe Thread

Hi Tony — Sorry I'm late — was offline for a spell. The "business about specifying a 2D rectangle" was 'way back in this thread — I was trying to consolidate the comments of a couple of people — what you say about a gas object being attached to a CUBE makes all the difference! Thanks. Watt & Watt is very useful for me. 450 double-columned pages, 1992, ACM Press & Addison-Wesley, hardcover, $45 list. Reviews the basics; treats aliasing well; good handling of illumination models, volume rendering, & RenderMan; excellent treatment of animation (forward & reverse kinematics, soft-body, & procedural). Authors are from England; associated with TDI. Less encyclopedic than Foley & van Dam's "Computer Graphics," but more in-depth. Wonderfully opinionated, too. They describe a flame animation. A 2D rectangle, perpendicular to the camera, is assigned a turbulence map that simulates fire. The flame's color at any coordinate on the rectangle depends on its (x,y) values — the color is yellow towards the center bottom, darkening through red to black at the upper and outer edges. With each frame, the rectangle is moved down in (y), while the position of the flame itself is clamped — identifiable elements in the flame pattern seem to rise, but its general shape and location stay the same. At the same time, the turbulence function itself is moved backward in (z) — this makes the pattern elements vary smoothly over time. The color photos are quite good, but I've yet to try the technique myself. Is this similar to how Aladdin handles gas animation? Other thoughts? regards, jd