GLUUNPROJECT

Section: Misc. Reference Manual Pages (3G)
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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 )

delim $$

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 ( down 70 {cpile { ~"objX" above ~"objY" above ~"objZ" above ~W}} ~~ right ) ~=~ INV(P M) left ( down 140 {cpile { { {2("winX" ~-~ "view"[0])} over {"view" [2]} ~-~ 1 } above { {2("winY" ~-~ "view"[1])} over {"view"[3]} ~-~ 1 } above { 2("winZ") ~-~ 1 } above 1}} ~~ right ) $INV()$ denotes matrix inversion. W is an unused variable, included for consistent matrix notation.