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_GENERATE_MIPMAP_HINT
, GL_LINE_SMOOTH_HINT
, GL_PERSPECTIVE_CORRECTION_HINT
, and GL_POINT_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_GENERATE_MIPMAP_HINT
Indicates the desired quality and performance of automatic mipmap level generation.
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,
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.
Copyright © 2003-2004 Silicon Graphics, Inc.
This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.