gluUnProject(3G) OpenGL Reference 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 GLTRUE indicates success; a return
value of GLFALSE 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
| | | view[3] |
| objZ | | |
2(winZ) - 1
( ) | |
W
( 1 )
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gluUnProject(3G) OpenGL Reference gluUnProject(3G)
INV() denotes matrix inversion. W is an unused variable, included for
consistent matrix notation.
SEE ALSO
glGet, gluProject
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