GLHINT() MachTen Programmer’s Manual GLHINT()

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 con-
stant indicating the behavior to be controlled, and mode
is another symbolic constant indicating the desired behav-
ior. 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 speci-
fied 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
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 inter-
polation is not efficiently supported
by the GL implementation, hinting
GL_DONT_CARE or GL_FASTEST can result
in simple linear interpolation of col-
ors and/or texture coordinates.

GL_POINT_SMOOTH_HINT
Indicates the sampling quality of
antialiased points. If a larger fil-
ter function is applied, hinting
GL_NICEST can result in more pixel
fragments being generated during ras-
terization,

GL_POLYGON_SMOOTH_HINT
Indicates the sampling quality of
antialiased polygons. Hinting
GL_NICEST can result in more pixel
fragments being generated during ras-
terization, if a larger filter func-
tion 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
execution of glEnd.

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