GLEVALPOINT(3gl)GLEVALPOINT(3gl)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 com‐
mand. 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
computed from i⋅Δu+u1 is exactly u2, and if j=m, then the value com‐
puted from j⋅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, glEvalMesh, glMap1, glMap2, glMapGrid
15 Mar 97 GLEVALPOINT(3gl)