glHint

glHint

NAME

glHint -- specify implementation-specific hints

C SPECIFICATION

void glHint(GLenum target,

GLenum mod)

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. 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

The client doesn't have a 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. Hinting GL_NICEST can result in more pixel fragments being generated during rasterization, if a larger filter function is applied.

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. Hinting GL_NICEST can result in more pixel fragments being generated during rasterization, if a larger filter function is applied.

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. glHint can be ignored.

ERRORS

GL_INVALID_ENUM is generated if target or mode is not an accepted value.

GL_INVALID_OPERATION is generated if glHint is called between a call to glBegin and the corresponding call to glEnd.