glSampleCoverage — specify multisample coverage parameters
void glSampleCoverage( | GLclampf value, |
GLboolean invert); |
valueSpecify a single floating-point sample coverage value. The value is clamped to the range . 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.
Multisampling samples a pixel multiple times at various implementation-dependent subpixel locations to generate antialiasing effects. Multisampling transparently antialiases points, lines, and polygons 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.
glGet with argument GL_SAMPLE_COVERAGE_VALUE
glGet with argument GL_SAMPLE_COVERAGE_INVERT
glIsEnabled with argument GL_SAMPLE_ALPHA_TO_COVERAGE
glIsEnabled with argument GL_SAMPLE_COVERAGE
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