NAME

gluUnProject4 - map window and clip coordinates to object coordinates

C SPECIFICATION

GLint gluUnProject4( GLdouble winX,

	GLdouble winY,
	GLdouble winZ,
	GLdouble clipW,
	const GLdouble *model,
	const GLdouble *proj,
	const GLint *view,
	GLdouble near,
	GLdouble far,
	GLdouble* objX,
	GLdouble* objY,
	GLdouble* objZ,
	GLdouble* objW )

PARAMETERS

winX, winY, winZ

Specify the window coordinates to be mapped.

clipW

Specify the clip w coordinate 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).

near, far

Specifies the near and far planes (as from a glGetDoublev call).

objX, objY, objZ, objW

Returns the computed object coordinates.

DESCRIPTION

gluUnProject4 maps the specified window coordinates winX, winY and winZ and its clip w coordinate clipW into object coordinates (objX, objY, objZ, objW) using model, proj and view. clipW can be other than 1 as for vertices in glFeedbackBuffer when data type GL_4D_COLOR_TEXTURE is returned. This also handles the case where the near and far planes are different from the default, 0 and 1, respectively. A return value of GL_TRUE indicates success; a return value of GL_FALSE indicates failure.

To compute the coordinates (objX, objY, objZ and objW), gluUnProject4 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 - near)
----------------- - 1
(far - near)

clipW

INV() denotes matrix inversion.

gluUnProject4 is equivalent to gluUnProject when clipW is 1, near is 0 and far is 1.

NOTES

gluUnProject4 is available only if the GLU version is 1.3 or greater.

SEE ALSO

glGet, glFeedbackBuffer, gluProject, gluUnProject