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/**********************************************************************
arcball.cpp
--------------------------------------------------
GLUI User Interface Toolkit (LGPL)
Copyright (c) 1998 Paul Rademacher
Feb 1998, Paul Rademacher (rademach@cs.unc.edu)
Oct 2003, Nigel Stewart - GLUI Code Cleaning
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
**********************************************************************/
#include "arcball.h"
#include <cstdio>
/**************************************** Arcball::Arcball() ****/
/* Default (void) constructor for Arcball */
Arcball::Arcball()
{
rot_ptr = &rot;
init();
}
/**************************************** Arcball::Arcball() ****/
/* Takes as argument a mat4 to use instead of the internal rot */
Arcball::Arcball(mat4 *mtx)
{
rot_ptr = mtx;
}
/**************************************** Arcball::Arcball() ****/
/* A constructor that accepts the screen center and arcball radius*/
Arcball::Arcball(const vec2 &_center, float _radius)
{
rot_ptr = &rot;
init();
set_params(_center, _radius);
}
/************************************** Arcball::set_params() ****/
void Arcball::set_params(const vec2 &_center, float _radius)
{
center = _center;
radius = _radius;
}
/*************************************** Arcball::init() **********/
void Arcball::init()
{
center.set( 0.0, 0.0 );
radius = 1.0;
q_now = quat_identity();
*rot_ptr = identity3D();
q_increment = quat_identity();
rot_increment = identity3D();
is_mouse_down = false;
is_spinning = false;
damp_factor = 0.0;
zero_increment = true;
}
/*********************************** Arcball::mouse_to_sphere() ****/
vec3 Arcball::mouse_to_sphere(const vec2 &p)
{
float mag;
vec2 v2 = (p - center) / radius;
vec3 v3( v2[0], v2[1], 0.0 );
mag = v2*v2;
if ( mag > 1.0 )
v3.normalize();
else
v3[VZ] = (float) sqrt( 1.0 - mag );
/* Now we add constraints - X takes precedence over Y */
if ( constraint_x )
{
v3 = constrain_vector( v3, vec3( 1.0, 0.0, 0.0 ));
}
else if ( constraint_y )
{
v3 = constrain_vector( v3, vec3( 0.0, 1.0, 0.0 ));
}
return v3;
}
/************************************ Arcball::constrain_vector() ****/
vec3 Arcball::constrain_vector(const vec3 &vector, const vec3 &axis)
{
return (vector-(vector*axis)*axis).normalize();
}
/************************************ Arcball::mouse_down() **********/
void Arcball::mouse_down(int x, int y)
{
down_pt.set( (float)x, (float) y );
is_mouse_down = true;
q_increment = quat_identity();
rot_increment = identity3D();
zero_increment = true;
}
/************************************ Arcball::mouse_up() **********/
void Arcball::mouse_up()
{
q_now = q_drag * q_now;
is_mouse_down = false;
}
/********************************** Arcball::mouse_motion() **********/
void Arcball::mouse_motion(int x, int y, int shift, int ctrl, int alt)
{
/* Set the X constraint if CONTROL key is pressed, Y if ALT key */
set_constraints( ctrl != 0, alt != 0 );
vec2 new_pt( (float)x, (float) y );
vec3 v0 = mouse_to_sphere( down_pt );
vec3 v1 = mouse_to_sphere( new_pt );
vec3 cross = v0^v1;
q_drag.set( cross, v0 * v1 );
// *rot_ptr = (q_drag * q_now).to_mat4();
mat4 temp = q_drag.to_mat4();
*rot_ptr = *rot_ptr * temp;
down_pt = new_pt;
/* We keep a copy of the current incremental rotation (= q_drag) */
q_increment = q_drag;
rot_increment = q_increment.to_mat4();
set_constraints(false, false);
if ( q_increment.s < .999999 )
{
is_spinning = true;
zero_increment = false;
}
else
{
is_spinning = false;
zero_increment = true;
}
}
/********************************** Arcball::mouse_motion() **********/
void Arcball::mouse_motion(int x, int y)
{
mouse_motion(x, y, 0, 0, 0);
}
/***************************** Arcball::set_constraints() **********/
void Arcball::set_constraints(bool _constraint_x, bool _constraint_y)
{
constraint_x = _constraint_x;
constraint_y = _constraint_y;
}
/***************************** Arcball::idle() *********************/
void Arcball::idle()
{
if (is_mouse_down)
{
is_spinning = false;
zero_increment = true;
}
if (damp_factor < 1.0f)
q_increment.scale_angle(1.0f - damp_factor);
rot_increment = q_increment.to_mat4();
if (q_increment.s >= .999999f)
{
is_spinning = false;
zero_increment = true;
}
}
/************************ Arcball::set_damping() *********************/
void Arcball::set_damping(float d)
{
damp_factor = d;
}