glEvalPoint(3G) OpenGL Reference 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 Wu + u );
1
where
Wu = (u -u )/n
2 1
and n, u , and u are the arguments to the most recent glMapGrid1
1 2
command. The one absolute numeric requirement is that if i = n, then the
.
value computed from i Wu + u is exactly u .
1 2
In the two-dimensional case, glEvalPoint2, let
Wu = (u -u )/n
2 1
Wv = (v -v )/m,
2 1
where n, u , u , m, v , and v are the arguments to the most recent
1 2 1 2
glMapGrid2 command. Then the glEvalPoint2 command is equivalent to
calling
. .
glEvalCoord2( i Wu + u , j Wv + v );
1 1
The only absolute numeric requirements are that if i = n, then the value
.
computed from i Wu + u is exactly u , and if j = m, then the value
1 2
.
computed from i Wv + v is exactly v .
1 2
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glEvalPoint(3G) OpenGL Reference glEvalPoint(3G)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
MACHINE DEPENDENCIES
RealityEngine, RealityEngine2, and VTX systems do not handle 1D maps for
colors correctly.
SEE ALSO
glEvalCoord, glEvalMesh, glMap1, glMap2, glMapGrid
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