**glEvalPoint**

### 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*+*u1*);
where

*du* = (*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***du*+*u1* is exactly *u2*.

In the two-dimensional case, **glEvalPoint2**, let

*du* = (*u2*-*u1*)/*n*
*dv* = (*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***du*+*u1*, *j***dv*+*v1*);
The only absolute numeric requirements are that if *i* = *n*, then
the value computed from *i***du*+*u1* is exactly *u2*, and
if *j* = *m*, then the value computed from
*j***dv*+*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**,
**glEvalMesh**,
**glMap1**,
**glMap2**,
**glMapGrid**

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© *1995 Uwe Behrens. All rights reserved.*