Should gl_FragCoord work in something like the Image Filter example project?

Could it be made to work?

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Should gl_FragCoord work in

smokris's picture
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Should gl_FragCoord work in something like the Image Filter example project?

Yes; if I understand correctly, it should and does work.

In test.adjustColorBrightness.c, I replaced the contents of main() with this:

gl_FragColor = vec4(gl_FragCoord.x/640., gl_FragCoord.y/480., 0., 1.);

...and fed it a 640x480 image. It rendered the attached 2D gradient, which I believe is correct. I also tested it in a 3D object shader, and it correctly provides normalized depth coordinates, too.

(For 2D shaders with VuoImageRenderer, it may be easier to use varying vec4 fragmentTextureCoordinate; since that's already normalized to the size of the image.)

Are you seeing or expecting something different?