Method GL.glEvalPoint()
- Method glEvalPoint
void glEvalPoint(int|array(int) i, int|void j)
- 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 glEvalPoint is equivalent to calling .nf
glEvalCoord1(i . DELTA u + u ); 1 where
DELTA u = (u - u ) / n 2 1
and n, u , and u 1 2
.fi are the arguments to the most recent glMapGrid1 command. The one absolute numeric requirement is that if i~=~n, then the value computed from .nf i . DELTA u + u is exactly u . 1 2
.fi
In the two-dimensional case, glEvalPoint, let .nf 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
.fi are the arguments to the most recent glMapGrid2 command. Then the glEvalPoint command is equivalent to calling .nf
glEvalCoord2(i . DELTA u + u , j . DELTA v + v ); 1 1
.fi The only absolute numeric requirements are that if i~=~n, then the value computed from .nf
i . DELTA u + u is exactly u , 1 2 .fi and if j~=~m, then the value computed from .nf
j cdot DELTA v + v is exactly v . 1 2
- Parameter i
Specifies the integer value for grid domain variable i.
- Parameter j
Specifies the integer value for grid domain variable j (glEvalPoint only).