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 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_GENERATE_MIPMAP_HINT_EXT: Indicates whether performance or quality is important when generating mipmap images.
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. If a larger filter function is applied, 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. If a larger filter function is applied, 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. Some implementations ignore glHint settings.

EXTENSIONS

Some routines and constants for this function are part of an extension, not part of the core GL command set. The following extension names must be present in the string returned by glGetString when called with argument GL_EXTENSIONS to use these routines and constants.

GL_EXT_generate_mipmap: GL_GENERATE_MIPMAP_HINT_EXT is part of the EXT_generate_mipmap extension.

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.