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)
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*du+u1);
where
du = (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*du+u1 is exactly u2.
In the two-dimensional case, glEvalPoint2, let
du = (u2-u1)/n
dv = (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*du+u1, j*dv+v1);
The only absolute numeric requirements are that if i = n, then
the value computed from i*du+u1 is exactly u2, and
if j = m, then the value computed from
j*dv+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
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© 1995 Uwe Behrens. All rights reserved.