Hi All,
I have run in to some trouble with a shader that uses a dynamically
updated uniform (updated rarely but it does change). Everything works as
expected on all nvidia cards I have tried but I cannot get it to work on
an ATI card (FirePro V5700). All systems are running WinXP. I know ATIs
OpenGL drivers are terrible, but has anyone come across this problem and
has a suggestion on how to fix it?
I have made a realy simple shader to replicate the problem:
uniform int numActiveLayers; //updated dynamically
void main() {
vec4 col = texture2D(textures[0], gl_TexCoord[0].st);
if(numActiveLayers == 1) { //at first, always set to 1
gl_FragColor = col;
} else if(numActiveLayers > 999){ //this condition is never true
//} else if(1 > 999) { //if I change to this it all works fine. It
only executes this block if I test against the uniform
//does nothing but causes the problem, which means it is still
executed.
//There is no texture in unit 1 so it is fine to fail but it
shouldn't execute
vec4 layerCol = texture2D(textures[1],gl_TexCoord[0].st);
// Even when it is failing because of the above line, the output
fragment is not red.
gl_FragColor = vec4(1,0,0,1);
}
}
Any ideas would be greatly appreciated as I am completely stuck.
Cheers,
Brad
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