From f4092abdf94af6a99aff944d6264bc1284e8bdd4 Mon Sep 17 00:00:00 2001 From: Reinhard Tartler Date: Mon, 10 Oct 2011 17:43:39 +0200 Subject: Imported nx-X11-3.1.0-1.tar.gz Summary: Imported nx-X11-3.1.0-1.tar.gz Keywords: Imported nx-X11-3.1.0-1.tar.gz into Git repository --- .../main/doc/man/manglu/standard/lookat.gl | 108 +++++++++++++++++++++ 1 file changed, 108 insertions(+) create mode 100644 nx-X11/extras/ogl-sample/main/doc/man/manglu/standard/lookat.gl (limited to 'nx-X11/extras/ogl-sample/main/doc/man/manglu/standard/lookat.gl') diff --git a/nx-X11/extras/ogl-sample/main/doc/man/manglu/standard/lookat.gl b/nx-X11/extras/ogl-sample/main/doc/man/manglu/standard/lookat.gl new file mode 100644 index 000000000..09189de06 --- /dev/null +++ b/nx-X11/extras/ogl-sample/main/doc/man/manglu/standard/lookat.gl @@ -0,0 +1,108 @@ +_C_ License Applicability. Except to the extent portions of this file are +_C_ made subject to an alternative license as permitted in the SGI Free +_C_ Software License B, Version 1.1 (the "License"), the contents of this +_C_ file are subject only to the provisions of the License. You may not use +_C_ this file except in compliance with the License. You may obtain a copy +_C_ of the License at Silicon Graphics, Inc., attn: Legal Services, 1600 +_C_ Amphitheatre Parkway, Mountain View, CA 94043-1351, or at: +_C_ +_C_ http://oss.sgi.com/projects/FreeB +_C_ +_C_ Note that, as provided in the License, the Software is distributed on an +_C_ "AS IS" basis, with ALL EXPRESS AND IMPLIED WARRANTIES AND CONDITIONS +_C_ DISCLAIMED, INCLUDING, WITHOUT LIMITATION, ANY IMPLIED WARRANTIES AND +_C_ CONDITIONS OF MERCHANTABILITY, SATISFACTORY QUALITY, FITNESS FOR A +_C_ PARTICULAR PURPOSE, AND NON-INFRINGEMENT. +_C_ +_C_ Original Code. The Original Code is: OpenGL Sample Implementation, +_C_ Version 1.2.1, released January 26, 2000, developed by Silicon Graphics, +_C_ Inc. The Original Code is Copyright (c) 1991-2000 Silicon Graphics, Inc. +_C_ Copyright in any portions created by third parties is as indicated +_C_ elsewhere herein. All Rights Reserved. +_C_ +_C_ Additional Notice Provisions: The application programming interfaces +_C_ established by SGI in conjunction with the Original Code are The +_C_ OpenGL(R) Graphics System: A Specification (Version 1.2.1), released +_C_ April 1, 1999; The OpenGL(R) Graphics System Utility Library (Version +_C_ 1.3), released November 4, 1998; and OpenGL(R) Graphics with the X +_C_ Window System(R) (Version 1.3), released October 19, 1998. This software +_C_ was created using the OpenGL(R) version 1.2.1 Sample Implementation +_C_ published by SGI, but has not been independently verified as being +_C_ compliant with the OpenGL(R) version 1.2.1 Specification. +_C_ +_C_ $Date: 2004/03/14 08:29:09 $ $Revision: 1.1.1.4 $ +_C_ The first character in this file must be an '_'! +_C_ Anything on a line after _C_ is ignored +_define(_filters,eqn)_C_ +_C_ eqn is automatically replaced with neqn for nroff +_header(LookAt, define a viewing transformation) +_names(LookAt) +.EQ +delim $$ +.EN +.SH PARAMETERS +_phead(_param1 _param2 _param3) +Specifies the position of the eye point. +_phead(_param4 _param5 _param6) +Specifies the position of the reference point. +_phead(_param7 _param8 _param9) +Specifies the direction of the \f2up\fP vector. +.SH DESCRIPTION +_cmnd 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 {_eqnparam4 above _eqnparam5 above _eqnparam6} + ccol { ~-~ above ~-~ above ~-~} + ccol {_eqnparam1 above _eqnparam2 above _eqnparam3} +} } ~~ right ) + +.EN + +.sp +Let \f2UP\fP be the vector $(_eqnparam7, _eqnparam8, _eqnparam9)$. +.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 _cmnd is equivalent to +.Ex +glMultMatrixf(M); +glTranslated (-eyex, -eyey, -eyez); +.Ee +.SH SEE ALSO +_glcmnd(Frustum), _cmnd(Perspective) -- cgit v1.2.3