229 lines
4.5 KiB
Text
229 lines
4.5 KiB
Text
/***********************************************************************
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quaternion.cpp
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A quaternion class
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-------------------------------------------------------------------
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Feb 1998, Paul Rademacher (rademach@cs.unc.edu)
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************************************************************************/
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#include "quaternion.h"
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#include <math.h>
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#include "stdinc.h"
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/******************************************* constructors **************/
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quat::quat( void )
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{
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*this = quat_identity();
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}
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quat::quat(const float x, const float y, const float z, const float w)
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{
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v.set( x, y, z );
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s = w;
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}
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quat::quat( vec3 _v, float _s )
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{
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set( _v, _s );
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}
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quat::quat( float _s, vec3 _v )
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{
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set( _v, _s );
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}
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quat::quat( const float *d )
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{
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v[0] = d[0];
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v[1] = d[1];
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v[2] = d[2];
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s = d[3];
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}
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quat::quat( const double *d )
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{
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v[0] = d[0];
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v[1] = d[1];
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v[2] = d[2];
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s = d[3];
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}
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quat::quat( const quat &q )
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{
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v = q.v;
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s = q.s;
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}
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void quat::set( vec3 _v, float _s )
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{
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v = _v;
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s = _s;
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}
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quat& quat::operator = (const quat& q)
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{
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v = q.v; s = q.s; return *this;
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}
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/* ... */
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/******** quat friends ************/
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quat operator + (const quat &a, const quat &b)
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{
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return quat( a.s+b.s, a.v+b.v );
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}
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quat operator - (const quat &a, const quat &b)
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{
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return quat( a.s-b.s, a.v-b.v );
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}
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quat operator - (const quat &a )
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{
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return quat( -a.s, -a.v );
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}
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quat operator * ( const quat &a, const quat &b)
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{
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return quat( a.s*b.s - a.v*b.v, a.s*b.v + b.s*a.v + ((a.v)^(b.v)) );
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}
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quat operator * ( const quat &a, const float t)
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{
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return quat( a.v * t, a.s * t );
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}
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quat operator * ( const float t, const quat &a )
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{
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return quat( a.v * t, a.s * t );
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}
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mat4 quat::to_mat4( void )
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{
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float t, xs, ys, zs, wx, wy, wz, xx, xy, xz, yy, yz, zz;
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t = 2.0 / (v*v + s*s);
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xs = v[VX]*t; ys = v[VY]*t; zs = v[VZ]*t;
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wx = s*xs; wy = s*ys; wz = s*zs;
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xx = v[VX]*xs; xy = v[VX]*ys; xz = v[VX]*zs;
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yy = v[VY]*ys; yz = v[VY]*zs; zz = v[VZ]*zs;
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mat4 matrix( 1.0-(yy+zz), xy+wz, xz-wy, 0.0,
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xy-wz, 1.0-(xx+zz), yz+wx, 0.0,
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xz+wy, yz-wx, 1.0-(xx+yy), 0.0,
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0.0, 0.0, 0.0, 1.0 );
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return matrix;
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}
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/************************************************* quat_identity() *****/
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/* Returns quaternion identity element */
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quat quat_identity( void )
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{
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return quat( vec3( 0.0, 0.0, 0.0 ), 1.0 );
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}
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/************************************************ quat_slerp() ********/
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/* Quaternion spherical interpolation */
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quat quat_slerp( quat from, quat to, float t )
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{
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quat to1;
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double omega, cosom, sinom, scale0, scale1;
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/* calculate cosine */
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cosom = from.v * to.v + from.s + to.s;
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/* Adjust signs (if necessary) */
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if ( cosom < 0.0 ) {
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cosom = -cosom;
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to1 = -to;
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}
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else
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{
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to1 = to;
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}
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/* Calculate coefficients */
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if ((1.0 - cosom) > FUDGE ) {
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/* standard case (slerp) */
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omega = acos( cosom );
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sinom = sin( omega );
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scale0 = sin((1.0 - t) * omega) / sinom;
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scale1 = sin(t * omega) / sinom;
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}
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else {
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/* 'from' and 'to' are very close - just do linear interpolation */
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scale0 = 1.0 - t;
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scale1 = t;
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}
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return scale0 * from + scale1 * to1;
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}
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/********************************************** set_angle() ************/
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/* set rot angle (degrees) */
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void quat::set_angle( float f )
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{
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vec3 axis = get_axis();
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s = cos( DEG2RAD( f ) / 2.0 );
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v = axis * sin(DEG2RAD(f) / 2.0);
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}
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/********************************************** scale_angle() ************/
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/* scale rot angle (degrees) */
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void quat::scale_angle( float f )
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{
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set_angle( f * get_angle() );
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}
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/********************************************** get_angle() ************/
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/* get rot angle (degrees). Assumes s is between -1 and 1 */
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float quat::get_angle( void )
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{
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return RAD2DEG( 2.0 * acos( s ) );
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}
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/********************************************* get_axis() **************/
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vec3 quat::get_axis( void )
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{
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float scale;
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scale = sin( acos( s ) );
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if ( scale < FUDGE AND scale > -FUDGE )
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return vec3( 0.0, 0.0, 0.0 );
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else
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return v / scale;
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}
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/******************************************* quat::print() ************/
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void quat::print( FILE *dest, char *name )
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{
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fprintf( dest, "%s: v:<%3.2f %3.2f %3.2f> s:%3.2f\n", name,
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v[0], v[1], v[2], s );
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}
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