104 lines
2.8 KiB
Plaintext
104 lines
2.8 KiB
Plaintext
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'\" e
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'\"! eqn | mmdoc
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'\"macro stdmacro
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.ds Vn Version 1.2
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.ds Dt 6 March 1997
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.ds Re Release 1.2.0
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.ds Dp May 02 11:53
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.ds Dm 37 unproject
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.ds Xs 13294 5 unproject4.gl
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.TH GLUUNPROJECT4 3G
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.SH NAME
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.B "gluUnProject4
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\- map window and clip coordinates to object coordinates
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.SH C SPECIFICATION
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GLint \f3gluUnProject4\fP(
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GLdouble \fIwinX\fP,
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.nf
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.ta \w'\f3GLint \fPgluUnProject4( 'u
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GLdouble \fIwinY\fP,
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GLdouble \fIwinZ\fP,
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GLdouble \fIclipW\fP,
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const GLdouble \fI*model\fP,
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const GLdouble \fI*proj\fP,
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const GLint \fI*view\fP,
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GLdouble \fInear\fP,
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GLdouble \fIfar\fP,
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GLdouble* \fIobjX\fP,
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GLdouble* \fIobjY\fP,
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GLdouble* \fIobjZ\fP,
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GLdouble* \fIobjW\fP )
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.fi
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.EQ
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delim $$
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.EN
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.SH PARAMETERS
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.TP \w'\f2winX\fP\ \f2winY\fP\ \f2winZ\fP\ \ 'u
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\f2winX\fP, \f2winY\fP, \f2winZ\fP
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Specify the window coordinates to be mapped.
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.TP
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\f2clipW\fP
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Specify the clip w coordinate to be mapped.
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.TP
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\f2model\fP
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Specifies the modelview matrix (as from a \f3glGetDoublev\fP call).
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.TP
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\f2proj\fP
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Specifies the projection matrix (as from a \f3glGetDoublev\fP call).
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.TP
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\f2view\fP
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Specifies the viewport (as from a \f3glGetIntegerv\fP call).
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.TP
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\f2near\fP, \f2far\fP
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Specifies the near and far planes (as from a \f3glGetDoublev\fP call).
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.TP
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\f2objX\fP, \f2objY\fP, \f2objZ\fP, \f2objW\fP
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Returns the computed object coordinates.
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.SH DESCRIPTION
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\%\f3gluUnProject4\fP maps the specified window coordinates \f2winX\fP, \f2winY\fP and \f2winZ\fP
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and its clip w coordinate \f2clipW\fP
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into object
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coordinates (\f2objX\fP, \f2objY\fP, \f2objZ\fP, \f2objW\fP)
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using \f2model\fP, \f2proj\fP and \f2view\fP. \f2clipW\fP can be other than
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1 as for vertices in \f3glFeedbackBuffer\fP when data type
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\%\f3GL_4D_COLOR_TEXTURE\fP is returned.
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This also handles the case
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where the \f2near\fP and \f2far\fP planes are different from the default,
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0 and 1, respectively.
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A return
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value of \%\f3GL_TRUE\fP indicates success; a return value of \%\f3GL_FALSE\fP
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indicates failure.
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.P
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To compute the coordinates (\f2objX\fP, \f2objY\fP, \f2objZ\fP and \f2objW\fP),
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\%\f3gluUnProject4\fP multiplies the normalized device coordinates by the inverse of
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\f2model\fP*\f2proj\fP as follows:
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.P
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.ce
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.EQ
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left ( down 70 {cpile { ~"objX" above ~"objY" above ~"objZ"
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above ~"objW"}} ~~ right ) ~=~ INV(P M)
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left ( down 140 {cpile {
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{ {2("winX" ~-~ "view"[0])} over {"view"[2]} ~-~ 1 }
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above
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{ {2("winY" ~-~ "view"[1])} over {"view"[3]} ~-~ 1 }
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above
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{ {2("winZ" ~-~ "near")} over {("far" ~-~ "near")} ~-~ 1 }
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above
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"clipW"}} ~~ right )
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.EN
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.sp
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$INV()$ denotes matrix inversion.
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.P
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\%\f3gluUnProject4\fP is equivalent to \%\f3gluUnProject\fP when \f2clipW\fP is 1, \f2near\fP is 0 and
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\f2far\fP is 1.
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.SH NOTES
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\%\f3gluUnProject4\fP is available only if the GLU version is 1.3 or greater.
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.SH SEE ALSO
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\f3glGet(3G)\fP,
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\f3glFeedbackBuffer(3G)\fP,
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\%\f3gluProject(3G)\fP,
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\%\f3gluUnProject(3G)\fP
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