NAME
fglEvalPoint1, fglEvalPoint2 - generate and evaluate a
single point in a mesh
FORTRAN SPECIFICATION
SUBROUTINE fglEvalPoint1( INTEGER*4 i )
SUBROUTINE fglEvalPoint2( INTEGER*4 i,
INTEGER*4 j )
PARAMETERS
i Specifies the integer value for grid domain variable i.
j Specifies the integer value for grid domain variable j
(fglEvalPoint2 only).
DESCRIPTION
fglMapGrid and fglEvalMesh are used in tandem to efficiently
generate and evaluate a series of evenly spaced map domain
values. fglEvalPoint can be used to evaluate a single grid
point in the same gridspace that is traversed by
fglEvalMesh. Calling fglEvalPoint1 is equivalent to calling
glEvalCoord1(i . DELTA u + u );
1
where
DELTA u = (u - u ) / n
2 1
and n, u , and u
1 2
are the arguments to the most recent fglMapGrid1 command.
The one absolute numeric requirement is that if i = n, then
the value computed from
i . DELTA u + u is exactly u .
1 2
In the two-dimensional case, fglEvalPoint2, let
DELTA u = (u - u )/n
2 1
DELTA v = (v - v )/m
2 1
where n, u , u , m, v , and v
1 2 1 2
are the arguments to the most recent fglMapGrid2 command.
Then the fglEvalPoint2 command is equivalent to calling
glEvalCoord2(i . DELTA u + u , j . DELTA v + v );
1 1
The only absolute numeric requirements are that if i = n,
then the value computed from
i . DELTA u + u is exactly u ,
1 2
and if j = m, then the value computed from
j cdot DELTA v + v is exactly v .
1 2
ASSOCIATED GETS
fglGet with argument GL_MAP1_GRID_DOMAIN
fglGet with argument GL_MAP2_GRID_DOMAIN
fglGet with argument GL_MAP1_GRID_SEGMENTS
fglGet with argument GL_MAP2_GRID_SEGMENTS
SEE ALSO
fglEvalCoord, fglEvalMesh, fglMap1, fglMap2, fglMapGrid