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• Author : matthieu
  Date : 2006-11-29 17:01:51
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  Message : GLU manual pages from monolithic tree

• doc/gl-docs/GLU/project.3gl

• .\" $XFree86$
  '\" e
  '\"! eqn | mmdoc
  '\"macro stdmacro
  .ds Vn Version 1.2
  .ds Dt 6 March 1997
  .ds Re Release 1.2.0
  .ds Dp May 02 11:53
  .ds Dm 37 project.g
  .ds Xs 21974 4 project.gl
  .TH GLUPROJECT 3G
  .SH NAME
  .B "gluProject
  \- map object coordinates to window coordinates
  
  .SH C SPECIFICATION
  GLint \f3gluProject\fP(
  GLdouble \fIobjX\fP,
  .nf
  .ta \w'\f3GLint \fPgluProject( 'u
  	GLdouble \fIobjY\fP,
  	GLdouble \fIobjZ\fP,
  	const GLdouble \fI*model\fP,
  	const GLdouble \fI*proj\fP,
  	const GLint \fI*view\fP,
  	GLdouble* \fIwinX\fP,
  	GLdouble* \fIwinY\fP,
  	GLdouble* \fIwinZ\fP )
  .fi
  
  .EQ
  delim $$
  .EN
  .SH PARAMETERS
  .TP \w'\f2objX\fP\ \f2objY\fP\ \f2objZ\fP\ \ 'u 
  \f2objX\fP, \f2objY\fP, \f2objZ\fP
  Specify the object coordinates.
  .TP
  \f2model\fP
  Specifies the current modelview matrix (as from a \f3glGetDoublev\fP call).
  .TP
  \f2proj\fP
  Specifies the current projection matrix (as from a \f3glGetDoublev\fP call).
  .TP
  \f2view\fP
  Specifies the current viewport (as from a \f3glGetIntegerv\fP call).
  .TP
  \f2winX\fP, \f2winY\fP, \f2winZ\fP
  Return the computed window coordinates.
  .SH DESCRIPTION
  \%\f3gluProject\fP transforms the specified object coordinates into window coordinates
  using \f2model\fP, \f2proj\fP, and \f2view\fP. The result is stored 
  in \f2winX\fP, \f2winY\fP, and \f2winZ\fP. A return value of 
  \%\f3GL_TRUE\fP indicates success, a return value of \%\f3GL_FALSE\fP
  indicates failure.
  .P
  To compute the coordinates,
  let $v ~=~ ("objX", "objY", "objZ", 1.0)$
  represented as a matrix with 4 rows and 1 column.
  Then \%\f3gluProject\fP computes $v sup prime$
  as follows: 
  .sp
  .EQ
  v sup prime ~=~ P ~times~ M ~times~ v
  .EN
  .sp
  where $P$ is the current projection matrix \f2proj\fP, $M$ is the current
  modelview matrix \f2model\fP (both represented as
  $4 times 4$ matrices in column-major order) and '$times$' represents
  matrix multiplication. 
  .P 
  The window coordinates are then computed as follows: 
  .sp
  .EQ
  "winX" ~=~ "view" (0) ~+~ "view" (2) ~*~ (v sup prime (0) ~+~ 1)~/~2 
  .EN
  .sp
  .EQ
  "winY" ~=~ "view" (1) ~+~ "view" (3)~*~(v sup prime (1) ~+~ 1)~/~2
  .EN
  .sp
  .EQ
  "winZ" ~=~ (v sup prime (2)  ~+~ 1)~/~ 2
  .EN
  .sp
  .SH SEE ALSO
  \f3glGet(3G)\fP, \%\f3gluUnProject(3G)\fP