'\" 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 .EQ delim $$ .EN .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$^cdot^DELTA u ~+~ u sub 1$ ); \fP .RE .fi where .sp .in $DELTA u ~=~ ( u sub 2 - u sub 1 ) ^/^ n$ .in 0 .sp .P and $n$, $u sub 1$, and $u sub 2$ 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 $i ^cdot^ DELTA u ~+~ u sub 1$ is exactly $u sub 2$. .P In the two-dimensional case, \%\f3glEvalPoint2\fP, let .nf .IP $DELTA u ~=~ mark ( u sub 2 - u sub 1 ) ^/^ n$ .sp $DELTA v ~=~ mark ( v sub 2 - v sub 1 ) ^/^ m,$ .RE .fi .P where $n$, $u sub 1$, $u sub 2$, $m$, $v sub 1$, and $v sub 2$ are the arguments to the most recent \%\f3glMapGrid2\fP command. Then the \%\f3glEvalPoint2\fP command is equivalent to calling .nf .IP \f7 glEvalCoord2( i$^cdot^DELTA u ~+~ u sub 1$, j$^cdot^DELTA v ~+~ v sub 1$ ); \fP .RE .fi The only absolute numeric requirements are that if $i~=~n$, then the value computed from $i ^cdot^DELTA u ~+~ u sub 1$ is exactly $u sub 2$, and if $j~=~m$, then the value computed from $i ^cdot^DELTA v ~+~ v sub 1$ is exactly $v sub 2$. .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