BALL.H

Our vector contains pointers to ball and not pointers to gravityBall.
As a result, the compiler will call the function associated with ball unless we instruct it otherwise.
We can us the virtual directive to indicate that fall may be overriden by a derived class.
The compiler will then call the fall function overriden by the gravityBall object.

#include "sphere.h"

class ball :public sphere
	{
	public:
	ball(void);
	~ball(void);
virtual void fall(void);
	void expand(float);
	void setVelocity(float, float, float);
inline	float getXVelocity(void) { return xVelocity; }
inline	float getYVelocity(void) { return yVelocity; }
inline	float getZVelocity(void) { return zVelocity; }
	protected:
	float xVelocity;
	float yVelocity;
	float zVelocity;
	private:
	void resetVelocity(void);
	};