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Diffstat (limited to 'doc/gl-docs/GLU/lookat.3gl')
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diff --git a/doc/gl-docs/GLU/lookat.3gl b/doc/gl-docs/GLU/lookat.3gl new file mode 100644 index 000000000..e4a10d486 --- /dev/null +++ b/doc/gl-docs/GLU/lookat.3gl @@ -0,0 +1,101 @@ +'\" e +'\"! eqn | mmdoc +'\"macro stdmacro +.ds Vn Version 1.2 +.ds Dt 6 March 1997 +.ds Re Release 1.2.0 +.ds Dp May 02 11:53 +.ds Dm 37 lookat.gl +.ds Xs 1014 4 lookat.gl +.TH GLULOOKAT 3G +.SH NAME +.B "gluLookAt +\- define a viewing transformation + +.SH C SPECIFICATION +void \f3gluLookAt\fP( +GLdouble \fIeyeX\fP, +.nf +.ta \w'\f3void \fPgluLookAt( 'u + GLdouble \fIeyeY\fP, + GLdouble \fIeyeZ\fP, + GLdouble \fIcenterX\fP, + GLdouble \fIcenterY\fP, + GLdouble \fIcenterZ\fP, + GLdouble \fIupX\fP, + GLdouble \fIupY\fP, + GLdouble \fIupZ\fP ) +.fi + +.EQ +delim $$ +.EN +.SH PARAMETERS +.TP \w'\f2eyeX\fP\ \f2eyeY\fP\ \f2eyeZ\fP\ \ 'u +\f2eyeX\fP, \f2eyeY\fP, \f2eyeZ\fP +Specifies the position of the eye point. +.TP +\f2centerX\fP, \f2centerY\fP, \f2centerZ\fP +Specifies the position of the reference point. +.TP +\f2upX\fP, \f2upY\fP, \f2upZ\fP +Specifies the direction of the \f2up\fP vector. +.SH DESCRIPTION +\%\f3gluLookAt\fP creates a viewing matrix derived from an eye point, a reference +point indicating the center of the scene, and an \f2UP\fP vector. +.P +The matrix +maps the reference point to the negative \f2z\fP axis and the +eye point to the origin. +When a typical projection matrix is used, +the center of the scene therefore maps to the center of the viewport. +Similarly, the direction described by the \f2UP\fP +vector projected onto the viewing plane is mapped to the positive \f2y\fP +axis so that it points upward in the viewport. +The \f2UP\fP vector must not be parallel to the line of sight from the +eye point to the reference point. +.P +Let +.sp +.EQ +F ~=~ left ( down 20 { ~ matrix { + ccol {"centerX" above "centerY" above "centerZ"} + ccol { ~-~ above ~-~ above ~-~} + ccol {"eyeX" above "eyeY" above "eyeZ"} +} } ~~ right ) + +.EN + +.sp +Let \f2UP\fP be the vector $("upX", "upY", "upZ")$. +.P +Then normalize as follows: +.EQ +f ~=~ F over {|| F ||} +.EN +.P +.EQ +UP sup prime ~=~ UP over {|| UP ||} +.EN +.sp +.P +Finally, let $s ~=~ f ~times~ UP sup prime$, and $u ~=~ s ~times~ f$. +.P +.sp +M is then constructed as follows: +.EQ +M ~=~ left ( matrix { + ccol { ~s[0] above ~u[0] above -f[0] above 0 } + ccol { ~s[1] above ~u[1] above -f[1] above 0 } + ccol { ~s[2] above ~u[2] above -f[2] above 0 } + ccol { 0 above 0 above 0 above 1 } +} ~~right ) +.EN +.P +and \%\f3gluLookAt\fP is equivalent to +.Ex +glMultMatrixf(M); +glTranslated (-eyex, -eyey, -eyez); +.Ee +.SH SEE ALSO +\f3glFrustum(3G)\fP, \%\f3gluPerspective(3G)\fP |