glHint

GLHINT(3G)							   GLHINT(3G)



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 con-
       trolled, 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 sup-
			   ported   by	 the   GL   implementation,   hinting
			   GL_DONT_CARE	 or GL_FASTEST can result in per-ver-
			   tex 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	frag-
			   ments being generated during rasterization,

       GL_PERSPECTIVE_CORRECTION_HINT
			   Indicates the quality of color and texture coordi-
			   nate	 interpolation.	   If	perspective-corrected
			   parameter  interpolation  is	 not efficiently sup-
			   ported   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  rasteriza-
			   tion, 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.



								   GLHINT(3G)