/*Erin Piateski
Pd. 7 Graphics
5-7-98
Java applet which uses sprites to move pictures of 2 Gargoyles against a background.
When a collision with a wall is detected, they bounce off.  When a collision against
each other is detected, there is an explosion and the background changes.  Their
starting positions and movement against the new background are randomized. */

import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;
import java.util.*;

public class drawsprite extends Applet implements Runnable
{
//The main program.
 
	Image goliath,broadway,buffer,back,temp,exp;
	Graphics grdraw;
	usesprite bob,fred;  //sprites for the images of Goliath and Broadway
	collisions coll;
	Thread runner=null;
	Random randnum;
	
	//Beginning x and y position and movement values for the sprites
	int starter, startery, stmovx, stmovy,starter2, startery2, stmovx2, stmovy2;
	
	int yescoll;
	
	public void init()
	{
		//initializes necessary variables and creates classes.
		
		yescoll=0;
		goliath=getImage(getDocumentBase(),"goliath.gif");		//load needed images
		broadway=getImage(getDocumentBase(),"broadway.gif");
		exp=getImage(getDocumentBase(),"exp.gif");
		back=getImage(getDocumentBase(),"cartoon.gif");
		temp=getImage(getDocumentBase(),"blair.gif");
		
		buffer=createImage(768,576);
		grdraw=buffer.getGraphics();
		grdraw.setColor(Color.black);
		
		randnum=new Random();						//generate random values for sprite position and movement
		starter=Math.abs(randnum.nextInt()%626);
		startery=Math.abs(randnum.nextInt()%380);
		stmovx=Math.abs(randnum.nextInt()%10);
		stmovy=Math.abs(randnum.nextInt()%10);
		starter2=Math.abs(randnum.nextInt()%626);
		startery2=Math.abs(randnum.nextInt()%380);
		stmovx2=Math.abs(randnum.nextInt()%10);
		stmovy2=Math.abs(randnum.nextInt()%10);
		
		bob = new usesprite(starter,startery,stmovx,stmovy);
		fred= new usesprite(starter2,startery2,stmovx2,stmovy2);
		coll=new collisions(bob,fred,this);
	}

	public void paint(Graphics g)  //calls update
	{
		update(g);
	}
	
	public void Collide()
	{
	Image swap;		//swaps backgrounds using a temporary variable
					//tells the program there's been a collision
		
		yescoll=1;
		swap=back;
		back=temp;
		temp=swap;
	}
	
	
	public void update(Graphics g)
	{
	/* Paints the animation images on the screen */
	
		if(yescoll==0)		//if no collision, draws normally
		{
			grdraw.drawImage(back,0,0,this);
			grdraw.drawImage(broadway, bob.xpos, bob.ypos,this);
			grdraw.drawImage(goliath, fred.xpos, fred.ypos,this);
			g.drawImage(buffer,0,0,this);
		}
		else		//if collision, draws the explosion
		{
			grdraw.drawImage(exp,0,0,this); 
			g.drawImage(buffer,0,0,this);
			try{Thread.sleep(200);} 
			catch(InterruptedException e){};
			yescoll=0;	
		}
	}
		
	public void start()
	{
	/* Begins the running of the thread for the animation. */
	
		if(runner==null)
		{
			runner=new Thread(this);
			runner.start();
		}
	}
	
	public void stop()
	{
	/* Stops the running of the thread for the animation. */
	
		if (runner!=null && runner.isAlive())
			runner.stop();
		runner=null;
	}
	
	public void run()
	{
	/* implements the painting of the sprite images with a 
	lag time to slow it down. */
	
		int i;
		
		i=0;
		while(true)
		{
			repaint();			
			try{Thread.sleep(20);} 
			catch(InterruptedException e){};
		}
	}
}

public class collisions implements Runnable
{
/* Class for collision detection */

	Thread runner=null;
	
	//widths and heights of the edges of the sprite images
	int endwidb,endheib,endwidf,endheif;	
	
	usesprite bob,fred;
	drawsprite mainpro;
	
	public collisions(usesprite bob1,usesprite fred1,drawsprite prog)
	{
	//Constructor for the collisions class.
	
		bob=bob1;
		fred=fred1;
		mainpro=prog;
		start();
	}
	
	public void start()
	{
	/* Begins the running of the thread for the collision detection. */
	
		if(runner==null)
		{
			runner=new Thread(this);
			runner.start();
		}
	}
	
	public void stop()
	{
	/* Stops the running of the thread for the collision detection. */
	
		if (runner!=null && runner.isAlive())
			runner.stop();
		runner=null;
	}
	
	public void run()
	{
	/* Checks for collisions of the sprites*/
	int collide;
		
		while(true)
		{
			collide=0;
			
			endwidf=fred.xpos+122;		//calculates positions of ends of sprites
			endheif=fred.ypos+165;		//uses shrunken rectangles
			endheib=bob.ypos+158;
			endwidb=bob.xpos+114; 
			
			//check to see if edges of the sprites overlap
			if(((bob.xpos>fred.xpos)&&(bob.xpos<endwidf)) &&((bob.ypos>fred.ypos)&&(bob.ypos<endheif))) collide=1;
			if(((endwidb>fred.xpos)&&(endwidb<endwidf)) &&((endheib>fred.ypos)&&(endheib<endheif))) collide=1;
			if(((endwidb>fred.xpos)&&(endwidb<endwidf)) &&((bob.ypos>fred.ypos)&&(bob.ypos<endheif))) collide=1;
			if(((bob.xpos>fred.xpos)&&(bob.xpos<endwidf)) &&((endheib>fred.ypos)&&(endheib<endheif))) collide=1;
			
			if(collide==1)	//if there's a collision, chooses new random positions for the sprites
							//and activates a function in the main program
			{
				mainpro.Collide();
				
				bob.xpos=Math.abs(mainpro.randnum.nextInt()%626);
				bob.ypos=Math.abs(mainpro.randnum.nextInt()%380);
				
				fred.xpos=Math.abs(mainpro.randnum.nextInt()%626);
				fred.ypos=Math.abs(mainpro.randnum.nextInt()%380);
				
				bob.xmove=Math.abs(mainpro.randnum.nextInt()%10);
				bob.ymove=Math.abs(mainpro.randnum.nextInt()%10);
				
				fred.xmove=Math.abs(mainpro.randnum.nextInt()%10);
				fred.ymove=Math.abs(mainpro.randnum.nextInt()%10);

			} 
			try{Thread.sleep(10);} 		//allow time before a new collision can occur
			catch(InterruptedException e){};
		}
	}

}

public class usesprite implements Runnable
{
//Class for controlling sprite movement

	int xpos,ypos, xmove, ymove;
	Thread runner=null;
	
	public usesprite(int startx, int starty, int xmov, int ymov)
	{
		//Constructor for the usesprite class.
		
		xpos=startx;
		ypos=starty;
		xmove=xmov;
		ymove=ymov;
		start();
	}
	
	public void start()
	{
	/* Begins the running of the thread for the animation. */
	
		if(runner==null)
		{
			runner=new Thread(this);
			runner.start();
		}
	}
	
	public void stop()
	{
	/* Stops the running of the thread for the animation. */
	
		if (runner!=null && runner.isAlive())
			runner.stop();
		runner=null;
	}
	
	public void run()
	{
	/* implements the painting of the sprite images with a 
	lag time to slow it down. */
	
		int i;
		
		i=0;
		while(true) //endless loop to keep the program running
		{
			//change x and y positions
			
			xpos=xpos+xmove;	
			ypos=ypos+ymove;
			
			//if the sprite hits a wall, reverse x and y movement to make it bounce off
			if((ypos<=0) || (ypos>=380))
				ymove=-ymove;
			if((xpos<=0) || (xpos>=626))
				xmove=-xmove;		
			try{Thread.sleep(40);} 		//keeps the movement from being too fast
			catch(InterruptedException e){};
		}
	}
}