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propan
08-02-2004, 04:05 AM
Hi There!

I have a simple question concerning projection shadows. at the moment i'm only rendering simple projected shadows (no stencil buffer used in my main application). they are - of course - black. this works fine on every gfx card around here. i calculate a projection matrix that is multiplicated with the current modelview matrix. after that i set the color to black while re-rendering the model. looks okay.

when enabling GL_FOG, i get a weird problem. on all NVidia Cards, the shadows are fogged correctly, but on ATI they have only the fog color. nothing else... my shadows don't disappear in the fog, they already are completely fogged.

some screenshots may give you a better explanation:

i reproduced my problem in a simple GLUT test application. all those teapots are indicating the fog color, and the center teapot casts a shadow.

B]this shot is from a NVidia graphics board (gf4)[/B]
http://pro.dword.org/nvidia.jpg

and this from ATI (radeon9600)
http://pro.dword.org/ati.jpg

I have really nice fogged shadows on the GF4, but not on ATI.

i'm stuck with this for a couple of days now, and i don't have any real solution :( (

can you give me some advice?

i would post the source code, if necessary.

thanks in advance,

thomas