gl_SamplePosition.3G man page
gl_SamplePosition — contains the location of the current sample within the current fragment
in vec2 gl_SamplePosition ;.SH "DESCRIPTION"
gl_SamplePosition is a fragment language input variable that contains the location within a fragment of the sample currently being processed. The x and y components of gl_SamplePosition contain the sub-pixel coordinate of the current sample and will have values in the range 0.0 to 1.0. The sub-pixel coordinates of the center of the pixel are always (0.5, 0.5). Any static use of gl_SamplePosition causes the entire fragment shader to be evaluated per-sample rather than per-fragment. When rendering to a non-multisample buffer, or if multisample rasterization is disabled, gl_SamplePosition will be (0.5, 0.5).
|OpenGL Shading Language Version|
gl_SampleID(), gl_SampleMask(), gl_FragCoord()
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Copyright © 2011-2014 Khronos Group