gluUnProject

map window coordinates to object coordinates

C Specification

GLint gluUnProject(GLdouble  winX,
 GLdouble  winY,
 GLdouble  winZ,
 const GLdouble *  model,
 const GLdouble *  proj,
 const GLint *  view,
 GLdouble*  objX,
 GLdouble*  objY,
 GLdouble*  objZ);

Parameters

winX, winY, winZ

Specify the window coordinates to be mapped.

model

Specifies the modelview matrix (as from a glGetDoublev call).

proj

Specifies the projection matrix (as from a glGetDoublev call).

view

Specifies the viewport (as from a glGetIntegerv call).

objX, objY, objZ

Returns the computed object coordinates.

Description

gluUnProject maps the specified window coordinates into object coordinates using model, proj, and view. The result is stored in objX, objY, and objZ. A return value of GLU_TRUE indicates success; a return value of GLU_FALSE indicates failure.

To compute the coordinates objX objY objZ , gluUnProject multiplies the normalized device coordinates by the inverse of model * proj as follows:

objX objY objZ W = INV ⁡ P ⁢ M ⁢ 2 ⁡ winX - view ⁡ 0 view ⁡ 2 - 1 2 ⁡ winY - view ⁡ 1 view ⁡ 3 - 1 2 ⁡ winZ - 1 1

INV denotes matrix inversion. W is an unused variable, included for consistent matrix notation.

See Also

gluProject, glGet

Copyright

Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.