GLEVALPOINT(3G) GLEVALPOINT(3G)
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./u+u1 );
where
/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./u+u1 is exactly u2.
In the two-dimensional case, glEvalPoint2, let
/u=(u2-u1)/n
/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./u+u1, j./v+v1 );
The only absolute numeric requirements are that if i=n, then the value computed from i./u+u1 is exactly u2, and if j=m, then the value
computed from i./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(3G), glEvalMesh(3G), glMap1(3G), glMap2(3G), glMapGrid(3G)
GLEVALPOINT(3G)