glHint Subroutine

OpenGL 1.1 for AIX: Reference Manual

glHint Subroutine

Purpose

Specifies implementation-specific hints.

Library

OpenGL C bindings library: libGL.a

C Syntax

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. Mode can be one of the following three:

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 does not have a preference. This is the initial setting for all hints.

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:

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 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.
GL_SUBPIXEL_HINT_IBM	Indicates if primitives are rendered using subpixel sampling techniques. Hinting GL_NICEST can result in a greater accuracy of pixels turned on when a primitive is rendered. GL_FASTEST and GL_DONT_CARE may result in faster, non-subpixel positioned, rendering of some primitives.

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.

Notes

The interpretation of hints depends on the implementation. The glHint subroutine can be ignored.

Errors

GL_INVALID_ENUM	Either Target or Mode is not an accepted value.
GL_INVALID_OPERATION	The glHint subroutine is called between a call to glBegin and the corresponding call to glEnd.

Files

/usr/include/GL/gl.h

Contains C language constants, variable type definitions, and ANSI function prototypes for OpenGL.

Related Information

The glBegin or glEnd subroutine.

OpenGL Overview.