glEvalPoint(3G)		       OpenGL Reference		       glEvalPoint(3G)

NAME    [Toc]    [Back]

     glEvalPoint1, glEvalPoint2	- generate and evaluate	a single point in a
     mesh

C SPECIFICATION    [Toc]    [Back]

     void glEvalPoint1(	GLint i	)
     void glEvalPoint2(	GLint i,
			GLint j	)

PARAMETERS    [Toc]    [Back]

     i	Specifies the integer value for	grid domain variable i.

     j	Specifies the integer value for	grid domain variable j (glEvalPoint2
	only).

DESCRIPTION    [Toc]    [Back]

     glMapGrid and glEvalMesh are used in tandem to efficiently	generate and
     evaluate a	series of evenly spaced	map domain values.  glEvalPoint	can be
     used to evaluate a	single grid point in the same gridspace	that is
     traversed by glEvalMesh.  Calling glEvalPoint1 is equivalent to calling


			 .
	  glEvalCoord1(	i Wu + u  );
				  1

     where

	  Wu = (u -u )/n
		   2  1


     and n, u ,	and u  are the arguments to the	most recent glMapGrid1
	     1	     2
     command.  The one absolute	numeric	requirement is that if i = n, then the
			  .
     value computed from i Wu +	u  is exactly u	.
				   1		 2

     In	the two-dimensional case, glEvalPoint2,	let

	  Wu = (u -u )/n
		   2  1

	  Wv = (v -v )/m,
		   2  1

     where n, u	, u , m, v , and v  are	the arguments to the most recent
	       1   2	  1	  2
     glMapGrid2	command.  Then the glEvalPoint2	command	is equivalent to
     calling


			 .	      .
	  glEvalCoord2(	i Wu + u , j Wv	+ v  );
				  1	       1

     The only absolute numeric requirements are	that if	i = n, then the	value
		    .
     computed from i Wu	+ u  is	exactly	u , and	if j = m, then the value
			     1		   2
		    .
     computed from i Wv	+ v  is	exactly	v .
			     1		   2




									Page 1






glEvalPoint(3G)		       OpenGL Reference		       glEvalPoint(3G)

ASSOCIATED GETS    [Toc]    [Back]

     glGet with	argument GL_MAP1_GRID_DOMAIN
     glGet with	argument GL_MAP2_GRID_DOMAIN
     glGet with	argument GL_MAP1_GRID_SEGMENTS
     glGet with	argument GL_MAP2_GRID_SEGMENTS


MACHINE	DEPENDENCIES
     RealityEngine, RealityEngine2, and	VTX systems do not handle 1D maps for
     colors correctly.

SEE ALSO    [Toc]    [Back]

     glEvalCoord, glEvalMesh, glMap1, glMap2, glMapGrid


									PPPPaaaaggggeeee 2222