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_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.

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_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.

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.

Copyright

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/.