GLEVALPOINT()GLEVALPOINT()NAME
glEvalPoint1, glEvalPoint2 - generate and evaluate a single point in a
mesh
C SPECIFICATION
void glEvalPoint1( GLint i )
void glEvalPoint2( GLint i,
GLint j )
delim $$
PARAMETERS
i Specifies the integer value for grid domain variable $i$.
j Specifies the integer value for grid domain variable $j$ (glEval‐
Point2 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 . 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 glMapGrid1 command. The one abso‐
lute 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, glEvalPoint2, 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 glMapGrid2 command. Then the glE‐
valPoint2 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
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
GLEVALPOINT()
