MAIN.CXX

We can use random number generation and the delete statment to create a more flexible simulation.
Once a ball has been deleted, we must remove it from the vector with the erase method.
When an item is removed from a vector, the remaining indices shift down by one and the size decreases.
In order to avoid problems with indexing, we can use an iterator to access the items in the vector.
An iterator is a pointer to an item in a vector that we can iterate through in a for loop.

#include <vector.h>
#include <iostream.h>
#include "ball.h"

int main (void)
	{
	sphere mySphere;
	mySphere.setRadius(10.0);
	cout << "mySphere has radius: " << mySphere.getRadius() << endl;
	sphere myOtherSphere;
	myOtherSphere.copy(mySphere);
	myOtherSphere.setPosition(3.0,4.0,10.0);
	cout << "myOtherSphere has radius: " << myOtherSphere.getRadius() << endl;
	cout << "myOtherSphere has X position: " << myOtherSphere.getXPosition() << endl;
	vector<ball*> myBallArray;
	//create a new ball
	myBallArray.push_back(new ball);
	//initialize the ball position
	myBallArray[0]->setPosition(3.0,4.0,10.0);
	myBallArray[0]->setRadius(20.0);
	myBallArray[0]->setVelocity(0.2,0.0,1.0);
	int ballNumber = 0;
	while (1)
		{
		//report the ball position and velocity of the last ball created
		cout << "myBall has position X: " << myBallArray[ballNumber]->getXPosition();
		cout << " Y: " << myBallArray[ballNumber]->getYPosition();
		cout << " Z: " << myBallArray[ballNumber]->getZPosition() << endl;
		cout << "myBall has velocity X: " << myBallArray[ballNumber]->getXVelocity();
		cout << " Y: " << myBallArray[ballNumber]->getYVelocity();
		cout << " Z: " << myBallArray[ballNumber]->getZVelocity() << endl;
		vector<ball*>::iterator i;
		for (i=myBallArray.begin(); i!=myBallArray.end(); i++)
			{
			//simulate the ball flight
			(*i)->fall();
			//delete the ball if resting
			if ((*i)->getZPosition() <= 0.0)
				{
				//delete the ball from memory
				delete (*i);
				//delete the ball from the vector
				myBallArray.erase(i);
				//decrement the number of balls in flight
				ballNumber--;
				}
			}
		//generate a random number between 0 and 100
		int randomNumber = random()%100;
		//create a new ball 50 percent of the time
		if (randomNumber < 50)
			{
			//increment the number of balls in flight
			ballNumber++;
			//create a new ball
			myBallArray.push_back(new ball);
			//initialize the ball position
			myBallArray[ballNumber]->setPosition(3.0,4.0,10.0);
			myBallArray[ballNumber]->setRadius(20.0);
			myBallArray[ballNumber]->setVelocity(0.2,0.0,1.0);
			}
		}
	};