324 lines
8.6 KiB
C++
324 lines
8.6 KiB
C++
/*
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* (c) Copyright 1993, 1994, Silicon Graphics, Inc.
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* ALL RIGHTS RESERVED
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* Permission to use, copy, modify, and distribute this software for
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* any purpose and without fee is hereby granted, provided that the above
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* copyright notice appear in all copies and that both the copyright notice
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* and this permission notice appear in supporting documentation, and that
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* the name of Silicon Graphics, Inc. not be used in advertising
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* or publicity pertaining to distribution of the software without specific,
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* written prior permission.
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*
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* THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS"
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* AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
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* INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
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* FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL SILICON
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* GRAPHICS, INC. BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
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* SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY
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* KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION,
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* LOSS OF PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF
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* THIRD PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC. HAS BEEN
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* ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON
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* ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE
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* POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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* US Government Users Restricted Rights
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* Use, duplication, or disclosure by the Government is subject to
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* restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
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* (c)(1)(ii) of the Rights in Technical Data and Computer Software
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* clause at DFARS 252.227-7013 and/or in similar or successor
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* clauses in the FAR or the DOD or NASA FAR Supplement.
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* Unpublished-- rights reserved under the copyright laws of the
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* United States. Contractor/manufacturer is Silicon Graphics,
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* Inc., 2011 N. Shoreline Blvd., Mountain View, CA 94039-7311.
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*
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* OpenGL(TM) is a trademark of Silicon Graphics, Inc.
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*/
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/*
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* Trackball code:
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*
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* Implementation of a virtual trackball.
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* Implemented by Gavin Bell, lots of ideas from Thant Tessman and
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* the August '88 issue of Siggraph's "Computer Graphics," pp. 121-129.
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*
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* Vector manip code:
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*
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* Original code from:
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* David M. Ciemiewicz, Mark Grossman, Henry Moreton, and Paul Haeberli
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*
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* Much mucking with by:
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* Gavin Bell
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*/
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#include <cmath>
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#include <trackball.h>
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/*
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* This size should really be based on the distance from the center of
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* rotation to the point on the object underneath the mouse. That
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* point would then track the mouse as closely as possible. This is a
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* simple example, though, so that is left as an Exercise for the
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* Programmer.
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*/
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#define TRACKBALLSIZE (0.8f)
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/*
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* Local function prototypes (not defined in trackball.h)
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*/
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static double tb_project_to_sphere( double, double, double );
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static void normalize_quat( double [4] );
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void vzero( double *v )
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{
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v[0] = 0.0;
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v[1] = 0.0;
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v[2] = 0.0;
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}
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void vset( double *v, double x, double y, double z )
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{
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v[0] = x;
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v[1] = y;
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v[2] = z;
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}
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void vsub( const double *src1, const double *src2, double *dst )
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{
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dst[0] = src1[0] - src2[0];
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dst[1] = src1[1] - src2[1];
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dst[2] = src1[2] - src2[2];
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}
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void vcopy( const double *v1, double *v2 )
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{
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register int i;
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for( i = 0 ; i < 3 ; i++ )
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v2[i] = v1[i];
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}
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void vcross( const double *v1, const double *v2, double *cross )
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{
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double temp[3];
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temp[0] = (v1[1] * v2[2]) - (v1[2] * v2[1]);
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temp[1] = (v1[2] * v2[0]) - (v1[0] * v2[2]);
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temp[2] = (v1[0] * v2[1]) - (v1[1] * v2[0]);
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vcopy(temp, cross);
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}
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double vlength( const double *v )
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{
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return (double) sqrt( v[0] * v[0] + v[1] * v[1] + v[2] * v[2] );
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}
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void vscale( double *v, double div )
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{
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v[0] *= div;
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v[1] *= div;
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v[2] *= div;
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}
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void vnormal( double *v )
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{
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vscale( v, 1.0f / vlength( v ) );
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}
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double vdot( const double *v1, const double *v2 )
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{
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return v1[0]*v2[0] + v1[1]*v2[1] + v1[2]*v2[2];
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}
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void vadd( const double *src1, const double *src2, double *dst )
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{
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dst[0] = src1[0] + src2[0];
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dst[1] = src1[1] + src2[1];
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dst[2] = src1[2] + src2[2];
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}
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/*
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* Ok, simulate a track-ball. Project the points onto the virtual
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* trackball, then figure out the axis of rotation, which is the cross
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* product of P1 P2 and O P1 (O is the center of the ball, 0,0,0)
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* Note: This is a deformed trackball-- is a trackball in the center,
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* but is deformed into a hyperbolic sheet of rotation away from the
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* center. This particular function was chosen after trying out
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* several variations.
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*
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* It is assumed that the arguments to this routine are in the range
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* (-1.0 ... 1.0)
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*/
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void trackball( double q[4], double p1x, double p1y, double p2x, double p2y )
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{
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double a[3]; /* Axis of rotation */
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double phi; /* how much to rotate about axis */
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double p1[3], p2[3], d[3];
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double t;
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if( p1x == p2x && p1y == p2y )
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{
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/* Zero rotation */
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vzero( q );
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q[3] = 1.0;
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return;
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}
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/*
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* First, figure out z-coordinates for projection of P1 and P2 to
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* deformed sphere
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*/
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vset( p1, p1x, p1y, tb_project_to_sphere( TRACKBALLSIZE, p1x, p1y ) );
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vset( p2, p2x, p2y, tb_project_to_sphere( TRACKBALLSIZE, p2x, p2y ) );
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/*
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* Now, we want the cross product of P1 and P2
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*/
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vcross(p2,p1,a);
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/*
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* Figure out how much to rotate around that axis.
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*/
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vsub( p1, p2, d );
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t = vlength( d ) / (2.0f * TRACKBALLSIZE);
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/*
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* Avoid problems with out-of-control values...
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*/
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if( t > 1.0 )
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t = 1.0;
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if( t < -1.0 )
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t = -1.0;
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phi = 2.0f * (double) asin( t );
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axis_to_quat( a, phi, q );
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}
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/*
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* Given an axis and angle, compute quaternion.
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*/
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void axis_to_quat( double a[3], double phi, double q[4] )
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{
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vnormal( a );
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vcopy( a, q );
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vscale( q, (double) sin( phi / 2.0) );
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q[3] = (double) cos( phi / 2.0 );
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}
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/*
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* Project an x,y pair onto a sphere of radius r OR a hyperbolic sheet
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* if we are away from the center of the sphere.
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*/
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static double tb_project_to_sphere( double r, double x, double y )
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{
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double d, z;
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d = (double) sqrt( x*x + y*y );
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if( d < r * 0.70710678118654752440 )
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{ /* Inside sphere */
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z = (double) sqrt( r*r - d*d );
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}
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else
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{ /* On hyperbola */
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const double t = r / 1.41421356237309504880f;
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z = t*t / d;
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}
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return z;
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}
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/*
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* Given two rotations, e1 and e2, expressed as quaternion rotations,
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* figure out the equivalent single rotation and stuff it into dest.
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*
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* This routine also normalizes the result every RENORMCOUNT times it is
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* called, to keep error from creeping in.
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*
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* NOTE: This routine is written so that q1 or q2 may be the same
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* as dest (or each other).
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*/
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#define RENORMCOUNT 97
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void add_quats( double q1[4], double q2[4], double dest[4] )
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{
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static int count=0;
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double t1[4], t2[4], t3[4];
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double tf[4];
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vcopy( q1, t1 );
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vscale( t1, q2[3] );
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vcopy( q2, t2 );
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vscale( t2, q1[3] );
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vcross( q2, q1, t3 );
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vadd( t1, t2, tf );
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vadd( t3, tf, tf );
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tf[3] = q1[3] * q2[3] - vdot( q1, q2 );
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dest[0] = tf[0];
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dest[1] = tf[1];
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dest[2] = tf[2];
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dest[3] = tf[3];
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if( ++count > RENORMCOUNT )
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{
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count = 0;
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normalize_quat( dest );
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}
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}
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/*
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* Quaternions always obey: a^2 + b^2 + c^2 + d^2 = 1.0
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* If they don't add up to 1.0, dividing by their magnitued will
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* renormalize them.
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*
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* Note: See the following for more information on quaternions:
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*
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* - Shoemake, K., Animating rotation with quaternion curves, Computer
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* Graphics 19, No 3 (Proc. SIGGRAPH'85), 245-254, 1985.
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* - Pletinckx, D., Quaternion calculus as a basic tool in computer
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* graphics, The Visual Computer 5, 2-13, 1989.
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*/
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static void normalize_quat( double q[4] )
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{
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int i;
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double mag;
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mag = (q[0]*q[0] + q[1]*q[1] + q[2]*q[2] + q[3]*q[3]);
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for( i = 0; i < 4; i++ )
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q[i] /= mag;
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}
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/*
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* Build a rotation matrix, given a quaternion rotation.
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*
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*/
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void build_rotmatrix( float m[4][4], double q[4] )
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{
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m[0][0] = (float)(1.0 - 2.0 * (q[1] * q[1] + q[2] * q[2]));
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m[0][1] = (float)(2.0 * (q[0] * q[1] - q[2] * q[3]));
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m[0][2] = (float)(2.0 * (q[2] * q[0] + q[1] * q[3]));
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m[0][3] = 0.0f;
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m[1][0] = (float)(2.0 * (q[0] * q[1] + q[2] * q[3]));
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m[1][1] = (float)(1.0 - 2.0f * (q[2] * q[2] + q[0] * q[0]));
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m[1][2] = (float)(2.0 * (q[1] * q[2] - q[0] * q[3]));
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m[1][3] = 0.0f;
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m[2][0] = (float)(2.0 * (q[2] * q[0] - q[1] * q[3]));
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m[2][1] = (float)(2.0 * (q[1] * q[2] + q[0] * q[3]));
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m[2][2] = (float)(1.0 - 2.0 * (q[1] * q[1] + q[0] * q[0]));
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m[2][3] = 0.0f;
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m[3][0] = 0.0f;
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m[3][1] = 0.0f;
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m[3][2] = 0.0f;
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m[3][3] = 1.0f;
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}
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