NAME¶
gl_FragCoord - contains the window-relative coordinates of the current fragment
DECLARATION¶
in vec4 gl_FragCoord ;.SH "DESCRIPTION"
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().
gl_FragCoord may be redeclared with the additional layout qualifier
identifiers
origin_upper_left or
pixel_center_integer. By
default,
gl_FragCoord assumes a lower-left origin for window
coordinates and assumes pixel centers are located at half-pixel centers. For
example, the (x, y) location (0.5, 0.5) is returned for the lower-left-most
pixel in a window. The origin of
gl_FragCoord may be changed by
redeclaring
gl_FragCoord with the
origin_upper_left identifier.
The values returned can also be shifted by half a pixel in both x and y by
pixel_center_integer so it appears the pixels are centered at whole
number pixel offsets. This moves the (x, y) value returned by
gl_FragCoord of (0.5, 0.5) by default to (0.0, 0.0) with
pixel_center_integer.
If
gl_FragCoord is redeclared in any fragment shader in a program, it
must be redeclared in all fragment shaders in that program that have static
use of
gl_FragCoord. Redeclaring
gl_FragCoord with any accepted
qualifier affects only
gl_FragCoord.x and
gl_FragCoord.y. It has
no affect on rasterization, transformation or any other part of the OpenGL
pipline or language features.
VERSION SUPPORT¶
|
OpenGL Shading Language Version |
|
|
|
|
|
|
|
|
|
|
|
Variable Name |
1.10 |
1.20 |
1.30 |
1.40 |
1.50 |
3.30 |
4.00 |
4.10 |
4.20 |
4.30 |
4.40 |
4.50 |
gl_FragCoord |
✔ |
✔ |
✔ |
✔ |
✔ |
✔ |
✔ |
✔ |
✔ |
✔ |
✔ |
✔ |
SEE ALSO¶
gl_FragCoord()
COPYRIGHT¶
Copyright © 2011-2014 Khronos Group. This material may be distributed
subject to the terms and conditions set forth in the Open Publication License,
v 1.0, 8 June 1999.
http://opencontent.org/openpub/.
COPYRIGHT¶
Copyright © 2011-2014 Khronos Group