gl_FragCoord — contains the window-relative coordinates of the current fragment
in highp vec4 gl_FragCoord ;
Available only in the fragment language,
gl_FragCoord is an input variable that contains the window relative coordinate (x, y, z, 1/w) values for the fragment. If multi-sampling, this value can be for any location within the pixel, or one of the fragment samples. This value is the result of fixed functionality that interpolates primitives after vertex processing to generate fragments. The z component is the depth value that would be used for the fragment's depth if no shader contained any writes to gl_FragDepth.
|OpenGL ES Shading Language Version|
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