OpenGL man pages
## glEvalPoint.3gl

## 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 );
1
where
du = (u -u )/n
2 1
and n, u , and u are the arguments to the most recent glMapGrid1 command.
1 2
The one absolute numeric requirement is that if i = n, then the value
computed from i·du + u is exactly u .
1 2
In the two-dimensional case, glEvalPoint2, let
du=(u -u )/n
2 1
dv=(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·du + u , j·dv + v );
1 1
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
1 2
computed from j·dv + v is exactly v .
1 2

## 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, glEvalMesh, glMap1, glMap2, glMapGrid

Introduction |
Alphabetic |
Specification

Last Edited: *
Fri Dec 6 11:18:03 EST 1996
*
by
*AFV*

Look here for legal stuff: Legal