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:

$\left(\begin{array}{c}\mathrm{objX}\\ \mathrm{objY}\\ \mathrm{objZ}\\ W\end{array}\right)=\mathrm{INV}\left(PM\right)\left(\begin{array}{c}\frac{2(\mathrm{winX}-\mathrm{view}[0])}{\mathrm{view}\left[2\right]}-1\\ \frac{2(\mathrm{winY}-\mathrm{view}[1])}{\mathrm{view}\left[3\right]}-1\\ 2\left(\mathrm{winZ}\right)-1\\ 1\end{array}\right)$ $\mathrm{INV}()$ denotes matrix inversion. W is an unused variable, included for consistent matrix notation.

SEE ALSO¶

glGet(3G), gluProject(3G)