GLAPI/glSampleCoverage

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glSampleCoverage
Core in version 4.4
Core since version 3.0

glSampleCoverage: specify multisample coverage parameters

Function Definition

 void glSampleCoverage(GLfloat value​, GLboolean invert​);
value
Specify a single floating-point sample coverage value. The value is clamped to the range [0, 1]. 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

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

The type of the value​ parameter was changed from GLclampf to GLfloat. This change is transparent to user code.

Associated Gets

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​

See Also

glSampleMask, glEnable(GL_SAMPLE_COVERAGE)

Copyright

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