Shockwaves

do you mean a vortex?

No, actually I wasn''t really talking about shockwaves in particular. I was wondering how to do that heat wave effect that you see above the grill.

Well, if you''re doing it to hardware, then I think the best way to do it would be this:

Render the area to a texture. Then, map that texture onto a grid of quads. Randomly displace some of the verteces in that grid. Now render the quad where the original section would have been.

In a high-quality raytracer, this would involve distorting rays using some sort of volumetric air-density map. This gets into advanced optics I know nothing about.

I''ve seen a vertex shader demo (probably on nvidia''s site) that does a wave effect similar to what you describe. Maybe the same method will work.

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http://www.3dcgi.com/