BALL.H

Although class ball has inherited each sphere member variable, only public and protected variables are accessible.

#include "sphere.h"

class ball :public sphere
	{
	public:
	ball(void);
	~ball(void);
	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);
	};

BALL.H

Private member variables must still be accessed using accessor functions just as they are by others.

include "ball.h"

ball::ball(void)
	{
	resetVelocity()
	}

ball::~ball(void)
	{
	}

void ball::resetVelocity(void)
	{
	xVelocity = 0.0;
	yVelocity = 0.0;
	zVelocity = 0.0;
	}

void ball::fall(void)
	{
	xPosition += xVelocity;
	yPosition += yVelocity;
	zPosition += zVelocity;
	if (zVelocity > 0.0 && zPosition >= 100.0)
		zVelocity = -zVelocity;
	else if (zVelocity < 0.0 && zPosition <= 0.0)
		resetVelocity();
	}

void ball::expand(float value)
	{
	float radiusValue;
	radiusValue = getRadius();
	radiusValue += value;
	setRadius(radiusValue);
	}

void ball::setVelocity(float xValue, float yValue, float zValue)
	{
	xVelocity = xValue;
	yVelocity = yValue;
	zVelocity = zValue;
	}