FragCoord
FragCoord
Decorating a variable with the FragCoord built-in decoration will make
that variable contain the framebuffer coordinate
of the fragment being processed.
The (x,y) coordinate (0,0) is the upper left corner of the upper
left pixel in the framebuffer.
When Sample Shading is enabled, the x and
y components of FragCoord reflect the location of one of the
samples corresponding to the shader invocation.
Otherwise, the x and y components of FragCoord reflect the
location of the center of the fragment.
The z component of FragCoord is the interpolated depth value of
the primitive.
The w component is the interpolated .
The Centroid interpolation decoration is ignored, but allowed, on
FragCoord.
Valid Usage
VUID-FragCoord-FragCoord-04210
The FragCoord decoration must be used only within the
Fragment Execution Model
VUID-FragCoord-FragCoord-04211
The variable decorated with FragCoord must be declared using the
Input Storage Class
VUID-FragCoord-FragCoord-04212
The variable decorated with FragCoord must be declared as a
four-component vector of 32-bit floating-point values