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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 dot DELTA(u) + u1 );
where

              DELTA(u) = ( 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 dot DELTA(u) + u1 is exactly u2.

In the two-dimensional case, glEvalPoint2, let

       DELTA(u) = ( u2 - u1 ) / n

       DELTA(v) = ( 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 dot DELTA(u) + u1, j dot DELTA(v) + v1 );
The  only absolute numeric requirements are that if i=n, then the value computed from i dot DELTA(u) + u1 is
exactly u2, and if j=m, then the value computed from i dot DELTA(v) + 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)