89 lines
2.1 KiB
Plaintext
89 lines
2.1 KiB
Plaintext
.\" $XFree86$
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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 project.g
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.ds Xs 21974 4 project.gl
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.TH GLUPROJECT 3G
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.SH NAME
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.B "gluProject
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\- map object coordinates to window coordinates
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.SH C SPECIFICATION
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GLint \f3gluProject\fP(
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GLdouble \fIobjX\fP,
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.nf
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.ta \w'\f3GLint \fPgluProject( 'u
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GLdouble \fIobjY\fP,
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GLdouble \fIobjZ\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* \fIwinX\fP,
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GLdouble* \fIwinY\fP,
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GLdouble* \fIwinZ\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'\f2objX\fP\ \f2objY\fP\ \f2objZ\fP\ \ 'u
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\f2objX\fP, \f2objY\fP, \f2objZ\fP
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Specify the object coordinates.
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.TP
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\f2model\fP
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Specifies the current 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 current 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 current viewport (as from a \f3glGetIntegerv\fP call).
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.TP
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\f2winX\fP, \f2winY\fP, \f2winZ\fP
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Return the computed window coordinates.
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.SH DESCRIPTION
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\%\f3gluProject\fP transforms the specified object coordinates into window coordinates
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using \f2model\fP, \f2proj\fP, and \f2view\fP. The result is stored
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in \f2winX\fP, \f2winY\fP, and \f2winZ\fP. A return value of
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\%\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,
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let $v ~=~ ("objX", "objY", "objZ", 1.0)$
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represented as a matrix with 4 rows and 1 column.
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Then \%\f3gluProject\fP computes $v sup prime$
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as follows:
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.sp
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.EQ
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v sup prime ~=~ P ~times~ M ~times~ v
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.EN
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.sp
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where $P$ is the current projection matrix \f2proj\fP, $M$ is the current
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modelview matrix \f2model\fP (both represented as
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$4 times 4$ matrices in column-major order) and '$times$' represents
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matrix multiplication.
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.P
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The window coordinates are then computed as follows:
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.sp
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.EQ
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"winX" ~=~ "view" (0) ~+~ "view" (2) ~*~ (v sup prime (0) ~+~ 1)~/~2
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.EN
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.sp
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.EQ
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"winY" ~=~ "view" (1) ~+~ "view" (3)~*~(v sup prime (1) ~+~ 1)~/~2
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.EN
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.sp
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.EQ
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"winZ" ~=~ (v sup prime (2) ~+~ 1)~/~ 2
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.EN
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.sp
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.SH SEE ALSO
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\f3glGet(3G)\fP, \%\f3gluUnProject(3G)\fP
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