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
       glapGrid and glEvalesh 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 glEvalesh.  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 glapGrid1 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 glapGrid2
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  com-
puted  from i dot DELTA(u) ] u1 is exactly u2, and if j=m, then the value com-
puted from i dot DELTA(v) ] v1 is exactly v2.

ASOCIATED GETS
       glGet with argument GLMAP1GRIDOMAIN
       glGet with argument GLMAP2GRIDOMAIN
       glGet with argument GLMAP1GRIDSEGMENTS
       glGet with argument GLMAP2GRIDSEGMENTS

SEE ALSO
       glEvalCoord, glEvalesh, glap1, glap2, glapGrid



                                                               GLEVALPOINT(3G)