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/**********************************************************************
arcball.cpp
--------------------------------------------------
Copyright (c) 1998 Paul Rademacher
This program is freely distributable without licensing fees and is
provided without guarantee or warrantee expressed or implied. This
program is -not- in the public domain.
**********************************************************************/
#include "arcball.h"
#include <stdio.h>
/**************************************** Arcball::Arcball() ****/
/* Default (void) constructor for Arcball */
Arcball::Arcball( void )
{
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( vec2 _center, float _radius )
{
rot_ptr = &rot;
init();
set_params( _center, _radius );
}
/************************************** Arcball::set_params() ****/
void Arcball::set_params( vec2 _center, float _radius )
{
center = _center;
radius = _radius;
}
/*************************************** Arcball::init() **********/
void Arcball::init( void )
{
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( 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] = 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( vec3 vector, 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( void )
{
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 )
{
(void)shift;
/* 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( void )
{
if ( is_mouse_down ) {
is_spinning = false;
zero_increment = true;
}
if ( damp_factor < 1.0 ) {
q_increment.scale_angle( 1.0 - damp_factor );
}
rot_increment = q_increment.to_mat4();
if ( q_increment.s >= .999999 ) {
is_spinning = false;
zero_increment = true;
}
}
/************************ Arcball::set_damping() *********************/
void Arcball::set_damping( float d )
{
damp_factor = d;
}
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