'\" e  
'\"macro stdmacro
.ds Vn Version 1.2
.ds Dt 24 September 1999
.ds Re Release 1.2.1
.ds Dp May 22 14:45
.ds Dm 0 May 22 14:
.ds Xs 57169     5
.TH GLEVALPOINT 3G
.SH NAME
.B "glEvalPoint1, glEvalPoint2
\- generate and evaluate a single point in a mesh

.SH C SPECIFICATION
void \f3glEvalPoint1\fP(
GLint \fIi\fP )
.nf
.fi
void \f3glEvalPoint2\fP(
GLint \fIi\fP,
.nf
.ta \w'\f3void \fPglEvalPoint2( 'u
	GLint \fIj\fP )
.fi

.SH PARAMETERS
.TP \w'\f2i\fP\ \ 'u 
\f2i\fP
Specifies the integer value for grid domain variable i.
.TP
\f2j\fP
Specifies the integer value for grid domain variable j
(\%\f3glEvalPoint2\fP only).
.SH DESCRIPTION
\%\f3glMapGrid\fP and \%\f3glEvalMesh\fP are used in tandem to efficiently
generate and evaluate a series of evenly spaced map domain values.
\%\f3glEvalPoint\fP can be used to evaluate a single grid point in the same gridspace
that is traversed by \%\f3glEvalMesh\fP.
Calling \%\f3glEvalPoint1\fP is equivalent to calling
.nf
.IP
\f7
glEvalCoord1( i dot DELTA(u) + u1 );
\fP
.RE
.fi
where
.sp
.in
DELTA(u) = ( u2 - u1 ) / n
.in 0
.sp
.P
and n, u1, and u2
are the arguments to the most recent \%\f3glMapGrid1\fP command.
The one absolute numeric requirement is that if i=n,
then the value computed from 
i dot DELTA(u) + u1 is exactly u2.
.P
In the two-dimensional case, \%\f3glEvalPoint2\fP, let 
.nf
.IP
DELTA(u) = ( u2 - u1 ) / n
.sp
DELTA(v) = ( v2 - v1 ) / m,
.RE
.fi
.P
where n, u1, u2, m, v1, and v2
are the arguments to the most recent \%\f3glMapGrid2\fP command.
Then the \%\f3glEvalPoint2\fP command is equivalent to calling
.nf
.IP
\f7
glEvalCoord2( i dot DELTA(u) + u1, j dot DELTA(v) + v1 );
\fP
.RE
.fi
The only absolute numeric requirements are that if i=n,
then the value computed from
i dot DELTA(u) + u1 is exactly u2,
and if j=m, then the value computed from 
i dot DELTA(v) + v1 is exactly v2.
.SH ASSOCIATED GETS
\%\f3glGet\fP with argument \%\f3GL_MAP1_GRID_DOMAIN\fP
.br
\%\f3glGet\fP with argument \%\f3GL_MAP2_GRID_DOMAIN\fP
.br
\%\f3glGet\fP with argument \%\f3GL_MAP1_GRID_SEGMENTS\fP
.br
\%\f3glGet\fP with argument \%\f3GL_MAP2_GRID_SEGMENTS\fP
.SH SEE ALSO
\%\f3glEvalCoord\fP,
\%\f3glEvalMesh\fP,
\%\f3glMap1\fP,
\%\f3glMap2\fP,
\%\f3glMapGrid\fP