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*du + u );
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where
du = (u -u )/n
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and n, u , and u are the arguments to the most recent glMapGrid1
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command. The one absolute numeric requirement is that if i = n, then the
value computed from i*du + u is exactly u .
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In the two-dimensional case, glEvalPoint2, let
du=(u -u )/n
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dv=(v -v )/m
2 1
where n, u , u , m, v , and v are the arguments to the most recent
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glMapGrid2 command. Then the glEvalPoint2 command is equivalent to
calling
glEvalCoord2(i*du + u , j*dv + v );
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The only absolute numeric requirements are that if i = n, then the value
computed from i*du + u is exactly u , and if j = m, then the value
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computed from j*dv + v is exactly v .
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glEvalPoint(3G) OpenGL Reference glEvalPoint(3G)
ASSOCIATED GETS
glGet with argument GLMAP1GRIDDOMAIN
glGet with argument GLMAP2GRIDDOMAIN
glGet with argument GLMAP1GRIDSEGMENTS
glGet with argument GLMAP2GRIDSEGMENTS
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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