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glHint(3G)


NAME

  glHint - specify implementation-specific hints


SYNOPSIS

  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_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,

  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,

  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.


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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