glSampleCoverage — specify multisample coverage parameters
void glSampleCoverage( | GLclampf | value, |
| GLboolean | invert); |
value
Specify a single floating-point sample coverage value. The value is
clamped to the range
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, polygons, bitmaps, 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.
GL_INVALID_OPERATION is generated if glSampleCoverage is executed between the
execution of glBegin and the corresponding execution of glEnd.
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
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