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[nilsk]

I was trying to do a simple stipple pattern in a glsl fragment shader via

doesn't work
ivec2 pixel = ivec2(gl_FragCoord.xy); if( ((pixel.x+pixel.y)%2)) discard;

but this doesn't discard any fragments at all. The silly thing is that if I add a not it works as expected. It also works if I explicitly convert the expression in the if clause to a bool.

does work
ivec2 pixel = ivec2(gl_FragCoord.xy); if( !((pixel.x+pixel.y)%2)) discard; //if( bool((pixel.x+pixel.y)%2)) discard;//works too

This happens pretty much in any shader I tried regardless of the other GL-state.

Os: Windows 7 64

Graphics Chipset    ATI Radeon HD 5800 Series

Device ID    6898

Driver Packaging Version    8.982-120727a-145524C-ATI

Catalyst Version: 12.8

OpenGL Version: 6.14.10.11762

[gsellers]

Hi,

This sounds like the compiler is having issues promoting the integer expression to a Boolean. Do you see any warnings from the shader compiler (glGetShaderInfoLog) or any output from a debug context? Also, could you try updating your driver to Catalyst 12.10? Let us know what you find and we'll go investigate.

Cheers,

Graham

[nilsk]

Same problem with version 12.10. With version 12.8 the infologs always contained something along the lines "fragment shader compiled successfully", with version 12.10 I get an empty info log.

[gsellers]

Okay, thanks. We'll dig deeper into this to see what's going on.

The change in info log output is expected. We recently removed the "shader compiled successfully" message because a number of applications were expecting an empty log on successful compilation rather than testing the COMPILE_STATUS flag.

Thanks,

Graham