arcball.cpp
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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;
- }