glEvalPoint(3) glEvalPoint(3)
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 dot DELTA(u) + u1 );
where
DELTA(u) = ( 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 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 glMapGrid2
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.
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(3), glEvalMesh(3), glMap1(3), glMap2(3), glMapGrid(3)
glEvalPoint(3)
Mac OS X 10.6 - Generated Thu Sep 17 20:20:19 CDT 2009