NAME¶

glEvalPoint - generate and evaluate a single point in a mesh

C SPECIFICATION¶

void glEvalPoint1(GLint i);

void glEvalPoint2(GLint i, GLint j);

PARAMETERS¶

i

j

DESCRIPTION¶

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


     	                  ⋅


     	                  Δ


     	                  u


     	              


     	              +


     	              


     	                  u


     	                  1


     	              


     	          


               );


         

where Δ u = u 2 - u 1 n

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

In the two-dimensional case, glEvalPoint2, let

Δ u = u 2 - u 1 n

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

glEvalCoord2( 
			
		        
			    
			        i
				⋅
			        Δ
		                u
			    
		            +
		            
		                u
		                1
		            
			    ,
			    
			    
			        j
				⋅
			        Δ
		                v
			    
		            +
		            
		                v
		                1
		            
			
		     );


            

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

ASSOCIATED GETS¶

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

SEE ALSO¶

glEvalCoord(), glEvalMesh(), glMap1(), glMap2(), glMapGrid()

COPYRIGHT¶

Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.

AUTHORS¶

opengl.org