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147 jab 1 
#ifndef _TrackBall_
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#define _TrackBall_
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#include "CGLA/Vec2i.h"
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#include "CGLA/Vec2f.h"
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#include "CGLA/Vec3f.h"
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#include "CGLA/Vec3Hf.h"
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#include "CGLA/Quaternion.h"
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namespace GLGraphics
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{
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	enum TrackBallAction
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		{
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			NO_ACTION = 0,
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			ROTATE_ACTION,
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			PAN_ACTION,
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			ZOOM_ACTION
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		};
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	/** \brief This class represents a virtual tracball.
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			Use it in GLUT, FLTK or other OpenGL programs to allow the user to
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			spin the model being rendered. It needs work to be used with non-GL
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			apps since it calls GL API functions. */
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	class QuatTrackBall
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	{
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		CGLA::Vec3f centre;
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		CGLA::Vec2i screen_centre;
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		unsigned width, height;
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		CGLA::Quaternion	qrot;
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		CGLA::Quaternion	qinc;
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		CGLA::Vec2f	trans;
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		CGLA::Vec3f scale;
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		float	ballsize;
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		float eye_dist;
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		CGLA::Vec2f last_pos;
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		TrackBallAction current_action;
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		void rotate(const CGLA::Vec2f&);
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		void pan(const CGLA::Vec2f&);
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		void zoom(const CGLA::Vec2f&);
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		void calcRotation(const CGLA::Vec2f&);
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		float projectToSphere(const CGLA::Vec2f&);
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		CGLA::Vec2f scalePoint(const CGLA::Vec2i&) const;
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		void set_position(const CGLA::Vec2f&);
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	public:
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		/** First constructor argument is the point we look at.
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				The second argument is the distance to eye point.
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				The third is the scaling factor
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				the last two arguments are the window dimensions. */
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		QuatTrackBall(const CGLA::Vec3f&, float, unsigned, unsigned);
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		/// Set window dimensions.
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		void set_screen_window(unsigned _width, unsigned _height)
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		{
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			width = _width;
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			height = _height;
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			screen_centre[0] = static_cast<int>(width/2.0f);
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			screen_centre[1] = static_cast<int>(height/2.0f);
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		}
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		/// set the centre point of rotation
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		void set_centre(const CGLA::Vec3f& _centre)
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		{
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			centre = _centre;
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		}
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		void set_screen_centre(const CGLA::Vec2i& _screen_centre)
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		{
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			screen_centre[0] = _screen_centre[0];
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			screen_centre[1] = height - _screen_centre[1];
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		}
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		const CGLA::Quaternion& get_rotation() const
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		{
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			return qrot;
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		}
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		void set_rotation(const CGLA::Quaternion& _qrot)
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		{
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			qrot = _qrot;
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		}
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		void set_eye_dist(float _eye_dist)
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		{
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			eye_dist = _eye_dist;
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		}
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		float get_eye_dist() const
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		{
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			return eye_dist;
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		}
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		/// Call GL to set up viewing.
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		void set_gl_modelview() const;
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		/** Spin. used both to spin while button is pressed and if the ball is just
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				spinning while program is idling. */
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		void do_spin();
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		bool is_spinning() const;
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		/// Zeroes the rotation value - makes everything stop.
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		void stop_spin();
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		/// Call this function to start action when mouse button is pressed
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		void grab_ball(TrackBallAction,const CGLA::Vec2i&);
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		/// Call this function to perform action when user drags mouse
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		void roll_ball(const CGLA::Vec2i&);
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		/// Call this function to stop action when mouse is released.
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		void release_ball()
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		{
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			current_action = NO_ACTION;
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		}
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		/// Returns true if the ball is `grabbed' and not released yet.
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		bool is_grabbed() const
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		{
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			if(current_action == NO_ACTION)
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				return false;
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			return true;
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		}
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		void get_view_param(CGLA::Vec3f& eye,
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												CGLA::Vec3f& _centre, CGLA::Vec3f& up) const;
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		TrackBallAction get_current_action()
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		{
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			return current_action;
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		}
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	};
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}
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namespace GFX = GLGraphics;
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#endif