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);

Parameters

objX, objY, objZ

Specify the object coordinates.

model

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

proj

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

view

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

winX, winY, winZ

Return the computed window coordinates.

Description

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

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/.