glSampleCoverage

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Specify multisample coverage parameters.

C Specification[edit]

void glSampleCoverage( GLfloat value, GLboolean invert );


Parameters[edit]

value - Specify a single floating-point sample coverage value. The value is clamped to the range [math][0,1][/math] . The initial value is 1.0.
invert - Specify a single boolean value representing if the coverage masks should be inverted. GL_TRUE and GL_FALSE are accepted. The initial value is GL_FALSE .


Description[edit]

Multisampling samples a pixel multiple times at various implementation-dependent subpixel locations to generate antialiasing effects. Multisampling transparently antialiases points, lines, polygons, and images if it is enabled.

 value is used in constructing a temporary mask used in determining which samples will be used in resolving the final fragment color. This mask is bitwise-anded with the coverage mask generated from the multisampling computation. If the invert flag is set, the temporary mask is inverted (all bits flipped) and then the bitwise-and is computed.

If an implementation does not have any multisample buffers available, or multisampling is disabled, rasterization occurs with only a single sample computing a pixel's final RGB color.

Provided an implementation supports multisample buffers, and multisampling is enabled, then a pixel's final color is generated by combining several samples per pixel. Each sample contains color, depth, and stencil information, allowing those operations to be performed on each sample.


Notes[edit]

The type of the value parameter was changed from GLclampf to GLfloat. This change is transparent to user code and is described in detail on the removedTypes page.


Associated Gets[edit]

 glGet with argument GL_SAMPLE_COVERAGE_VALUE 

 glGet with argument GL_SAMPLE_COVERAGE_INVERT 

 glIsEnabled with argument GL_MULTISAMPLE 

 glIsEnabled with argument GL_SAMPLE_ALPHA_TO_COVERAGE 

 glIsEnabled with argument GL_SAMPLE_ALPHA_TO_ONE 

 glIsEnabled with argument GL_SAMPLE_COVERAGE 


Version Support[edit]

 glSampleCoverage  2.0+

See Also[edit]

 glEnable , removedTypes 


Copyright[edit]

Copyright© 1991-2006 Silicon Graphics, Inc. Copyright© 2010-2014 Khronos Group. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.