glHint.3gl

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.	 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 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.

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Last Edited: Fri Dec 6 11:18:03 EST 1996 by AFV
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