GLEVALPOINT(3G) UNIX Programmer's Manual 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._**\_**u + u1 );
where
**_\_**u = (u2-u1)/n
and n, u1, and u2 are the arguments to the most recent
**glMapGrid1** command. The one absolute numeric requirement is
that if i = n, then the value computed from i._**\_**u + u1 is
exactly u2.
In the two-dimensional case, **glEvalPoint2**, let
**_\_**u = (u2-u1)/n
**_\_**v = (v2-v1)/m,
where n, u1, u2, m, v1, and v2 are the arguments to the most
recent **glMapGrid2** command. Then the **glEvalPoint2** command is
equivalent to calling
glEvalCoord2( i._**\_**u + u1, j._**\_**v + v1 );
The only absolute numeric requirements are that if i = n,
then the value computed from i._**\_**u + u1 is exactly u2, and
MirBSD #10-current Printed 2021-12-07 1
GLEVALPOINT(3G) UNIX Programmer's Manual GLEVALPOINT(3G)
if j = m, then the value computed from i._**\_**v + v1 is exactly
v2.

## 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(3G)**, **glEvalMesh(3G)**, **glMap1(3G)**, **glMap2(3G)**,
**glMapGrid(3G)**
MirBSD #10-current Printed 2021-12-07 2