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#include <iostream>
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#include "CGLA/CGLA.h"
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#include "TrackBall.h"
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#ifdef WIN32
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#include <windows.h>
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#endif
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#include <GL/glu.h>
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using namespace std;
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using namespace CGLA;
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namespace Graphics
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{
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TrackBall::TrackBall(const Vec3f& _centre,
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float _eye_dist,
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unsigned _width,
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unsigned _height):
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centre(_centre), eye_dist(_eye_dist), scale(0.5*_eye_dist),
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width(_width), height(_height)
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{
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// This size should really be based on the distance from the center of
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// rotation to the point on the object underneath the mouse. That
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// point would then track the mouse as closely as possible. This is a
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// simple example, though, so that is left as an exercise.
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ballsize = 2.0f;
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screen_centre = Vec2i(width/2, height/2);
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qrot = Quaternion(0.0, 0.0, 0.0, 1.0);
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qinc = Quaternion(0.0, 0.0, 0.0, 1.0);
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trans = Vec2f(0.0, 0.0);
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}
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void TrackBall::grab_ball(TrackBallAction act, const Vec2i& v)
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{
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set_position(scalePoint(v));
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current_action = act;
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}
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void TrackBall::roll_ball(const Vec2i& v)
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{
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Vec2f w = scalePoint(v);
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switch (current_action)
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{
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case ROTATE_ACTION:
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rotate(w);
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break;
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case PAN_ACTION:
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pan(w);
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break;
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case ZOOM_ACTION:
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zoom(w);
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break;
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}
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last_pos = w;
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}
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// Call this when the user does a mouse down.
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// Stop the trackball glide, then remember the mouse
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// down point (for a future rotate, pan or zoom).
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void TrackBall::set_position(const Vec2f& _last_pos)
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{
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stop_spin();
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last_pos = _last_pos;
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}
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// Rotationaly spin the trackball by the current increment.
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// Use this to implement rotational glide.
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void TrackBall::do_spin()
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{
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qrot = qrot*qinc;
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}
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// Cease any rotational glide by zeroing the increment.
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void TrackBall::stop_spin()
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{
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qinc.set(0.0, 0.0, 0.0, 1.0);
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}
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void TrackBall::rotate(const Vec2f& new_v)
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{
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calcRotation(new_v);
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do_spin();
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}
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void TrackBall::pan(const Vec2f& new_v)
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{
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trans += (new_v - last_pos) * Vec2f(scale[0], scale[1]);
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}
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void TrackBall::zoom(const Vec2f& new_v)
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{
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eye_dist += (new_v[1] - last_pos[1]) * scale[2];
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eye_dist = max(eye_dist, 0.01f);
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}
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void TrackBall::calcRotation(const Vec2f& new_pos)
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{
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// Check for zero rotation
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if (new_pos == last_pos)
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qinc = Quaternion();
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else
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{
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// Form two vectors based on input points, find rotation axis
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Vec3f p1 = Vec3f(new_pos[0], new_pos[1], projectToSphere(new_pos));
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Vec3f p2 = Vec3f(last_pos[0], last_pos[1], projectToSphere(last_pos));
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Vec3f q = cross(p1, p2); /* axis of rotation from p1 and p2 */
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float L = sqrt(1.0f-dot(q,q) / (dot(p1,p1) * dot(p2,p2)));
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q.normalize(); /* q' = axis of rotation */
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q *= sqrt((1 - L)/2); /* q' = q' * sin(phi) */
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qinc.set(q[0],q[1],q[2],sqrt((1 + L)/2));
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}
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}
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// Project an x,y pair onto a sphere of radius r OR a hyperbolic sheet
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// if we are away from the center of the sphere.
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float TrackBall::projectToSphere(const Vec2f& v)
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{
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float d, t, z;
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d = v.length();
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// Inside sphere
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if (d < ballsize * 0.70710678118654752440) {
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z = sqrt(ballsize*ballsize - d*d);
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}
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// On hyperbola
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else {
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t = ballsize / 1.41421356237309504880;
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z = t*t / d;
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}
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return z;
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}
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// Scales integer point to the range [-1, 1]
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Vec2f TrackBall::scalePoint(const Vec2i& v) const
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{
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Vec2f w(v[0],height - v[1]);
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w -= Vec2f(screen_centre);
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w /= Vec2f(width,height);
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w = CGLA::v_min(Vec2f(1.0f), CGLA::v_max(Vec2f(-1), 2*w));
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return w;
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}
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void TrackBall::get_view_param(Vec3f& eye, Vec3f& _centre, Vec3f& up) const
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{
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up = qrot.apply(Vec3f(0,1,0));
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Vec3f right = qrot.apply(Vec3f(1,0,0));
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_centre = centre - up * trans[1] - right * trans[0];
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eye = qrot.apply(Vec3f(0,0,1)*eye_dist) + _centre;
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}
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// Modify the current gl matrix by the trackball rotation and translation.
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void TrackBall::set_gl_modelview() const
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{
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glMatrixMode(GL_MODELVIEW);
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glLoadIdentity();
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Vec3f eye;
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Vec3f _centre;
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Vec3f up;
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get_view_param(eye, _centre, up);
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gluLookAt(eye[0], eye[1], eye[2],
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_centre[0], _centre[1], _centre[2],
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up[0],up[1],up[2]);
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}
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bool TrackBall::is_spinning() const
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{
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static const Quaternion null_quat(0,0,0,1);
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if(!(qinc == null_quat))
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return true;
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return false;
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}
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}
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