GLUUNPROJECT(3G)

NAME
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 GL_TRUE indicates success; a return value of GL_FALSE indicates failure.

To compute the coordinates (objX, objY, and objZ), gluUnProject multiplies the normalized device coordinates by the inverse of model*proj as follows:
                        2(winX - view[0])
                        ----------------- - 1
                        view[2]
    objX 2(winY - view[1])
    objY = INV(PM) ----------------- - 1
    objZ view[3]
     W
                        2(winZ) - 1
                        1

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

SEE ALSO
glGet, gluProject