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glHint - specify implementation-specific hints
void
glHint( GLenum target,
GLenum mode )
- target
- Specifies a symbolic constant indicating the behavior
to be controlled. GL_FOG_HINT, GL_LINE_SMOOTH_HINT, GL_PERSPECTIVE_CORRECTION_HINT,
GL_POINT_SMOOTH_HINT, and GL_POLYGON_SMOOTH_HINT are accepted.
- mode
- Specifies
a symbolic constant indicating the desired behavior. GL_FASTEST, GL_NICEST,
and GL_DONT_CARE are accepted.
Certain aspects of GL behavior,
when there is room for interpretation, can be controlled with hints. A hint
is specified with two arguments. target is a symbolic constant indicating
the behavior to be controlled, and mode is another symbolic constant indicating
the desired behavior. The initial value for each target is GL_DONT_CARE.
mode can be one of the following:
- GL_FASTEST
- The most efficient option
should be chosen.
- GL_NICEST
- The most correct, or highest quality, option
should be chosen.
- GL_DONT_CARE
- No preference.
Though the implementation aspects
that can be hinted are well defined, the interpretation of the hints depends
on the implementation. The hint aspects that can be specified with target,
along with suggested semantics, are as follows:
- GL_FOG_HINT
- Indicates the
accuracy of fog calculation. If per-pixel fog calculation is not efficiently
supported by the GL implementation, hinting GL_DONT_CARE or GL_FASTEST
can result in per-vertex calculation of fog effects.
- GL_LINE_SMOOTH_HINT
- Indicates the sampling quality of antialiased lines. If a larger filter
function is applied, hinting GL_NICEST can result in more pixel fragments
being generated during rasterization,
- GL_PERSPECTIVE_CORRECTION_HINT
- Indicates
the quality of color and texture coordinate interpolation. If perspective-corrected
parameter interpolation is not efficiently supported by the GL implementation,
hinting GL_DONT_CARE or GL_FASTEST can result in simple linear interpolation
of colors and/or texture coordinates.
- GL_POINT_SMOOTH_HINT
- Indicates the
sampling quality of antialiased points. If a larger filter function is applied,
hinting GL_NICEST can result in more pixel fragments being generated during
rasterization,
- GL_POLYGON_SMOOTH_HINT
- Indicates the sampling quality of
antialiased polygons. Hinting GL_NICEST can result in more pixel fragments
being generated during rasterization, if a larger filter function is applied.
The interpretation of hints depends on the implementation. Some implementations
ignore glHint settings.
GL_INVALID_ENUM is generated if either target
or mode is not an accepted value.
GL_INVALID_OPERATION is generated if glHint
is executed between the execution of glBegin and the corresponding execution
of glEnd.
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