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<STRONG>NAME</STRONG>
<STRONG>glEvalPoint1,</STRONG> <STRONG>glEvalPoint2</STRONG> - generate and evaluate a single
point in a mesh
<STRONG>C</STRONG> <STRONG>SPECIFICATION</STRONG>
void <STRONG>glEvalPoint1</STRONG>( GLint <EM>i</EM> )
void <STRONG>glEvalPoint2</STRONG>( GLint <EM>i</EM>,
GLint <EM>j</EM> )
<STRONG>PARAMETERS</STRONG>
<EM>i</EM> Specifies the integer value for grid domain variable i.
<EM>j</EM> Specifies the integer value for grid domain variable j
(<STRONG>glEvalPoint2</STRONG> only).
<STRONG>DESCRIPTION</STRONG>
<STRONG>glMapGrid</STRONG> and <STRONG>glEvalMesh</STRONG> are used in tandem to efficiently
generate and evaluate a series of evenly spaced map domain
values. <STRONG>glEvalPoint</STRONG> can be used to evaluate a single grid
point in the same gridspace that is traversed by <STRONG>glEvalMesh</STRONG>.
Calling <STRONG>glEvalPoint1</STRONG> is equivalent to calling
glEvalCoord1(i . DELTA u + u );
1
where
DELTA u = (u - u ) / n
2 1
and n, u , and u
1 2
are the arguments to the most recent <STRONG>glMapGrid1</STRONG> command.
The one absolute numeric requirement is that if i = n, then
the value computed from
i . DELTA u + u is exactly u .
1 2
In the two-dimensional case, <STRONG>glEvalPoint2</STRONG>, let
DELTA u = (u - u )/n
2 1
DELTA v = (v - v )/m
2 1
where n, u , u , m, v , and v
1 2 1 2
are the arguments to the most recent <STRONG>glMapGrid2</STRONG> command.
Then the <STRONG>glEvalPoint2</STRONG> command is equivalent to calling
glEvalCoord2(i . DELTA u + u , j . DELTA v + v );
1 1
The only absolute numeric requirements are that if i = n,
then the value computed from
i . DELTA u + u is exactly u ,
1 2
and if j = m, then the value computed from
j cdot DELTA v + v is exactly v .
1 2
<STRONG>ASSOCIATED</STRONG> <STRONG>GETS</STRONG>
<STRONG>glGet</STRONG> with argument <STRONG>GL_MAP1_GRID_DOMAIN</STRONG>
<STRONG>glGet</STRONG> with argument <STRONG>GL_MAP2_GRID_DOMAIN</STRONG>
<STRONG>glGet</STRONG> with argument <STRONG>GL_MAP1_GRID_SEGMENTS</STRONG>
<STRONG>glGet</STRONG> with argument <STRONG>GL_MAP2_GRID_SEGMENTS</STRONG>
<STRONG>SEE</STRONG> <STRONG>ALSO</STRONG>
<STRONG>glEvalCoord</STRONG>, <STRONG>glEvalMesh</STRONG>, <STRONG>glMap1</STRONG>, <STRONG>glMap2</STRONG>, <STRONG>glMapGrid</STRONG>
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