NAME

       glClipControl - control clip coordinate to window coordinate behavior

C SPECIFICATION

       void glClipControl(GLenum origin, GLenum depth);

PARAMETERS

       origin
           Specifies the clip control origin. Must be one of GL_LOWER_LEFT or GL_UPPER_LEFT.

       depth
           Specifies the clip control depth mode. Must be one of GL_NEGATIVE_ONE_TO_ONE or
           GL_ZERO_TO_ONE.

DESCRIPTION

       glClipControl controls the clipping volume behavior and the clip coordinate to window
       coordinate transformation behavior.

       The view volume is defined by $$z_{min} \leq z_c \leq w_c$$ where $z_{min} = -w_c$ when
       depth is GL_NEGATIVE_ONE_TO_ONE, and $z_{min} = 0$ when depth is GL_ZERO_TO_ONE.

       The normalized device coordinate $y_d$ is given by $$y_d = { { f \times y_c } \over w_c
       }$$ where $f = 1$ when origin is GL_LOWER_LEFT, and $f = -1$ when origin is GL_UPPER_LEFT.

       The window coordinate $z_w$ is given by $$z_w = s \times z_d + b$$ where $s = { { f - n }
       \over 2 }$ and $b = { {n + f} \over 2 }$ when depth is GL_NEGATIVE_ONE_TO_ONE, and $s = f
       - n$ and $b = n$ when depth is GL_ZERO_TO_ONE. $n$ and $f$ are the near and far depth
       range values set with glDepthRange().

       Finally, the polygon area computation defined by gl_FrontFacing() to determine if a
       polygon is front- or back-facing has its sign negated when origin is GL_UPPER_LEFT.

NOTES

       The default GL clip volume definition is for a origin of GL_LOWER_LEFT and a depth of
       GL_NEGATIVE_ONE_TO_ONE.

       An origin of GL_UPPER_LEFT and a depth of GL_ZERO_TO_ONE corresponds to Direct3D's clip
       volume definition.

       An origin of GL_UPPER_LEFT and a depth of GL_NEGATIVE_ONE_TO_ONE corresponds to the
       upper-left origin of the window coordinate system of Microsoft Windows and the X Window
       System.

       There is extensive discussion of the uses and further consequences of the different clip
       volume settings in the GL_ARB_clip_control extension specification in the OpenGL Registry
       at URL http://www.opengl.org/registry/.

ERRORS

       An GL_INVALID_ENUM error is generated if origin is not GL_LOWER_LEFT or GL_UPPER_LEFT.

       An GL_INVALID_ENUM error is generated if depth is not GL_NEGATIVE_ONE_TO_ONE or
       GL_ZERO_TO_ONE.

VERSION SUPPORT

       ┌──────────────┬───────────────────────────────────────────────────────────────────────┐
       │              │                OpenGL Version                                         │
       ├──────────────┼─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┤
       │Function      │ 2.0 │ 2.1 │ 3.0 │ 3.1 │ 3.2 │ 3.3 │ 4.0 │ 4.1 │ 4.2 │ 4.3 │ 4.4 │ 4.5 │
       │/             │     │     │     │     │     │     │     │     │     │     │     │     │
       │Feature       │     │     │     │     │     │     │     │     │     │     │     │     │
       │Name          │     │     │     │     │     │     │     │     │     │     │     │     │
       ├──────────────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┤
       │glClipControl │  -  │  -  │  -  │  -  │  -  │  -  │  -  │  -  │  -  │  -  │  -  │  ✔  │
       └──────────────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┘

SEE ALSO

       gl_ClipDistance(), gl_CullDistance(), gl_FrontFacing(), glDepthRange().

COPYRIGHT

       Copyright © 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 © 2014 Khronos Group

[FIXME: source]                             01/03/2018                          GLCLIPCONTROL(3G)