GLHINT(3G) UNIX Programmer's Manual 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 calcula-
tion. 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 cal-
culation of fog effects.
GL_LINE_SMOOTH_HINT Indicates the sampling quality of
antialiased lines. If a larger filter
function is applied, hinting GL_NICEST
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GLHINT(3G) UNIX Programmer's Manual GLHINT(3G)
can result in more pixel fragments being
generated during rasterization,
GL_PERSPECTIVE_CORRECTION_HINT
Indicates the quality of color and tex-
ture coordinate interpolation. If
perspective-corrected parameter interpo-
lation 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.
NOTES
The interpretation of hints depends on the implementation.
Some implementations ignore glHint settings.
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 corresponding exe-
cution of glEnd.
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