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• Author : matthieu
  Date : 2006-11-29 17:00:35
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  Message : OpenGL manual pages from monolithic tree.

• doc/gl-docs/GL/gl/evalpoint.3gl

• '\" e
  '\"! eqn | mmdoc
  '\"macro stdmacro
  .ds Vn Version 1.2
  .ds Dt 24 September 1999
  .ds Re Release 1.2.1
  .ds Dp Jan 14 18:30
  .ds Dm 01 evalpoint
  .ds Xs 57169 5 evalpoint.gl
  .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(3G)\fP,
  \%\f3glEvalMesh(3G)\fP,
  \%\f3glMap1(3G)\fP,
  \%\f3glMap2(3G)\fP,
  \%\f3glMapGrid(3G)\fP