heat effect

knock knock ...

I don''t think it''s cool at all.

some kind of dissortion. Seems like kind of random lines of the starting pixel''s color (all lines in same direction) and then again the other.

but as I stated, I rather find it UGLY

Maybe the way it appears in single frame doesn''t do the animated look justice.

i guess so, probably we should see the game, or an animation. Anyway, that is the effect i''d like to have, i.e. a sort of heat effect due to a jet engine steam. Would texture pixel disturb/distortion a way to do it ? I heard smt about this tecnique at the opengl forum, but couldn''t find any tutorial or explanation.

You have different possibilities to do that. A very neat way is using pixelshaders to select a certain mipmap level per pixel. That way, you can blur the image on per-pixel level (selecting a larger mipmap level will make the image look more blurred). AFAIK, there was a paper at nVidia''s dev site about a similar technique.

But you don''t get distortions using that technique. If you want refraction, then using a projective render-texture is always a good way. Copy the part of the framebuffer you''d like your heat-haze to be applied to into a texture (or render directly into it). Then project the texture back in screenspace, using a fine quad-mesh. If you warp the texture coordinates of the mesh while rendering it back, you automatically distort the rendered image. Compute an approximation of Snell''s law at each vertex, modulating the IOR (index of refraction) through a Perlin noise field. This technique gives extremely good results, but is quite CPU intensive.