GLHINT(3G) GLHINT(3G)
NAME
glHint - specify implementation-specific hints
C SPECIFICATION
void glHint( GLenum target,
GLenum mode )
PARAMETERS
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.
DESCRIPTION
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 perspec-tive-corrected perspective-corrected
tive-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 func-tion function
tion is applied, hinting GL_NICEST can result in more pixel fragments being gen-erated generated
erated 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.
NOTES
The interpretation of hints depends on the implementation. Some implementations ignore glHint set-tings. settings.
tings.
ERRORS
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 cor-responding corresponding
responding execution of glEnd.
GLHINT(3G)
|