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/***********************************************************************
quaternion.cc - A quaternion class
-------------------------------------------------------------------
GLUI User Interface Toolkit (LGPL)
Copyright (c) 1998 Paul Rademacher
WWW: http://sourceforge.net/projects/glui/
Forums: http://sourceforge.net/forum/?group_id=92496
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
************************************************************************
Feb 1998, Paul Rademacher (rademach@cs.unc.edu)
Oct 2003, Nigel Stewart - GLUI Code Cleaning
************************************************************************/
#include "quaternion.h"
#include <cmath>
/******************************************* constructors **************/
quat::quat()
{
*this = quat_identity();
}
quat::quat(const float x, const float y, const float z, const float w)
{
v.set( x, y, z );
s = w;
}
quat::quat(const vec3 &_v, const float _s)
{
set( _v, _s );
}
quat::quat(const float _s, const vec3 &_v)
{
set( _v, _s );
}
quat::quat(const float *d)
{
v[0] = d[0];
v[1] = d[1];
v[2] = d[2];
s = d[3];
}
quat::quat(const double *d)
{
v[0] = (float) d[0];
v[1] = (float) d[1];
v[2] = (float) d[2];
s = (float) d[3];
}
quat::quat(const quat &q)
{
v = q.v;
s = q.s;
}
void quat::set(const vec3 &_v, const float _s)
{
v = _v;
s = _s;
}
quat &quat::operator=(const quat &q)
{
v = q.v;
s = q.s;
return *this;
}
/******** quat friends ************/
quat operator + (const quat &a, const quat &b)
{
return quat( a.s+b.s, a.v+b.v );
}
quat operator - (const quat &a, const quat &b)
{
return quat( a.s-b.s, a.v-b.v );
}
quat operator - (const quat &a )
{
return quat( -a.s, -a.v );
}
quat operator * ( const quat &a, const quat &b)
{
return quat( a.s*b.s - a.v*b.v, a.s*b.v + b.s*a.v + (a.v^b.v) );
}
quat operator * ( const quat &a, const float t)
{
return quat( a.v * t, a.s * t );
}
quat operator * ( const float t, const quat &a )
{
return quat( a.v * t, a.s * t );
}
mat4 quat::to_mat4() const
{
float xs, ys, zs, wx, wy, wz, xx, xy, xz, yy, yz, zz;
float t = 2.0f / (v*v + s*s);
xs = v[VX]*t; ys = v[VY]*t; zs = v[VZ]*t;
wx = s*xs; wy = s*ys; wz = s*zs;
xx = v[VX]*xs; xy = v[VX]*ys; xz = v[VX]*zs;
yy = v[VY]*ys; yz = v[VY]*zs; zz = v[VZ]*zs;
mat4 matrix(
1.0f-(yy+zz), xy+wz, xz-wy, 0.0f,
xy-wz, 1.0f-(xx+zz), yz+wx, 0.0f,
xz+wy, yz-wx, 1.0f-(xx+yy), 0.0f,
0.0f, 0.0f, 0.0f, 1.0f );
return matrix;
}
/************************************************* quat_identity() *****/
/* Returns quaternion identity element */
quat quat_identity()
{
return quat( vec3( 0.0, 0.0, 0.0 ), 1.0 );
}
/************************************************ quat_slerp() ********/
/* Quaternion spherical interpolation */
quat quat_slerp(const quat &from, const quat &to, float t)
{
quat to1;
float omega, cosom, sinom, scale0, scale1;
/* calculate cosine */
cosom = from.v * to.v + from.s + to.s;
/* Adjust signs (if necessary) */
if ( cosom < 0.0 )
{
cosom = -cosom;
to1 = -to;
}
else
{
to1 = to;
}
/* Calculate coefficients */
if ((1.0 - cosom) > FUDGE )
{
/* standard case (slerp) */
omega = (float) acos( cosom );
sinom = (float) sin( omega );
scale0 = (float) sin((1.0 - t) * omega) / sinom;
scale1 = (float) sin(t * omega) / sinom;
}
else
{
/* 'from' and 'to' are very close - just do linear interpolation */
scale0 = 1.0f - t;
scale1 = t;
}
return scale0 * from + scale1 * to1;
}
/********************************************** set_angle() ************/
/* set rot angle (degrees) */
void quat::set_angle(float f)
{
vec3 axis = get_axis();
static const double halfradians=acos(-1.0)/360.0;
f *= halfradians;
s = (float) cos( f );
v = axis * (float) sin( f );
}
/********************************************** scale_angle() ************/
/* scale rot angle (degrees) */
void quat::scale_angle(float f)
{
set_angle( f * get_angle() );
}
/********************************************** get_angle() ************/
/* get rot angle (degrees). Assumes s is between -1 and 1 */
float quat::get_angle() const
{
static const double degrees2=360.0/acos(-1.0);
return (float) (acos( s ) * degrees2);
}
/********************************************* get_axis() **************/
vec3 quat::get_axis() const
{
float scale = (float) sin( acos( s ) );
if ( scale < FUDGE && scale > -FUDGE )
return vec3( 0.0, 0.0, 0.0 );
else
return v / scale;
}
/******************************************* quat::print() ************/
void quat::print(FILE *dest, const char *name) const
{
fprintf( dest, "%s: v:<%3.2f %3.2f %3.2f> s:%3.2f\n",
name, v[0], v[1], v[2], s );
}
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