gluProject — map object coordinates to window coordinates

C Specification

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


objX, objY, objZ

Specify the object coordinates.


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


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


Specifies the current viewport (as from a glGetIntegerv call).

winX, winY, winZ

Return the computed window coordinates.


gluProject transforms the specified object coordinates into window coordinates using model, proj, and view. The result is stored in winX, winY, and winZ. A return value of GLU_TRUE indicates success, a return value of GLU_FALSE indicates failure.

To compute the coordinates, let v = objX objY objZ 1.0 represented as a matrix with 4 rows and 1 column. Then gluProject computes v as follows:

v = P × M × v

where P is the current projection matrix proj and M is the current modelview matrix model (both represented as 4 × 4 matrices in column-major order).

The window coordinates are then computed as follows:

winX = view 0 + view 2 × v 0 + 1 2

winY = view 1 + view 3 × v 1 + 1 2

winZ = v 2 + 1 2

See Also

gluUnProject, glGet


Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see