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gl_FragDepth & gl_FragCoord.z

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Hi, I want to output custom depth values in my shader. If I simple pass the gl_FragCoord.z into the gl_FragDepth all is well. However I want to displace it, does anyone know how gl_FragCoord is calculate by the fixed function pipeline as this might give me some clues. I tried this for my depth correction....
gl_FragDepth = ((gl_FragCoord.z*gl_FragCoord.w) +depthOffset) / gl_FragCoord.w;


But this gave view dependent results, i.e the close I was to the object the more the depth was offset. Any help, clues would be greatly appreciated. GOCP

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Hi,

I am not sure, but I think the problem is that in the fragment shader perspective division has already occured so gl_FragCoord.w is always 1.0, and thus that is why adding your depth offset is view dependent. When considering depth offset, i think using gl_polygon_offset may be more adapted.

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