glEvalPoint2

GLEVALPOINT(3G)						      GLEVALPOINT(3G)



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


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


PARAMETERS
       i  Specifies the integer value for grid domain variable i.

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

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⋅Δu+u1 );

where

	      Δu=(u2−u1)/n


and  n,	 u1,  and u2 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⋅Δu+u1 is exactly u2.

In the two-dimensional case, glEvalPoint2, let

       Δu=(u2−u1)/n

       Δv=(v2−v1)/m,

where  n,  u1,	u2,  m,	 v1,  and  v2  are  the	 arguments to the most recent
glMapGrid2 command.  Then the glEvalPoint2 command is equivalent to calling


       glEvalCoord2( i⋅Δu+u1, j⋅Δv+v1 );

The only absolute numeric requirements are that if i=n, then the  value	 com-
puted  from  i⋅Δu+u1  is exactly u2, and if j=m, then the value computed from
i⋅Δv+v1 is exactly v2.

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(3G), glEvalMesh(3G), glMap1(3G), glMap2(3G), glMapGrid(3G)



							      GLEVALPOINT(3G)