// Applet to do inclined plane simulation
// Original: Gary D. Westfall
// Modisimplified: W. Bauer
// August, 1997; October 1997
import java.awt.*;
import java.applet.*;

public class plane extends Applet
{
	String imageName="hand.gif";
    public MediaTracker tracker;
	public Image image;
	Image offscreenImage;
	public void init() {
		// Get the hand image
		tracker= new MediaTracker(this);
		image=this.getImage(getDocumentBase(),imageName);
		tracker.addImage(image,0);
		try {
	    	tracker.waitForID(0);
		} catch (InterruptedException e) {
		}
		
		setBackground(Color.white);

		setupMyImage();
		centerCanvas c = new centerCanvas(offscreenImage,image);
		Panel westPanel;
		westPanel = new WestPanel(c);

		setLayout(new BorderLayout());
		add("East",westPanel);
		add("Center",c);
		repaint();
	}
	
	public void setupMyImage() {
		if (offscreenImage != null) {
			offscreenImage.flush();
		}
		offscreenImage=createImage(470,300);
	}
	
}

class centerCanvas extends Canvas {
	int left=30;
	int right=385;
	int step=50;
	boolean myBegin,myReset;
	double ang=20.0;;
	double oldang=20.0;
	double coefk=0.3;
	double coefs=0.36;
	double m1=25.0;
	double oldm1=25.0;
	double m2=0.0;
	double oldm2=0.0;
	Rectangle r;
	Image myOffImage;
	Image handImage;
	Graphics offg;
	int numCollisions;
	WestPanel westPanel;
	double a;
	double grav=9.81;
	int yoff;
	int ymax=0;
		
	public centerCanvas(Image offImage,Image i1) {
		myOffImage=offImage;
		handImage=i1;
		offg = offImage.getGraphics();
		myReset=true;
		repaint();
	}
	
	public void update(Graphics g){
		paint(g);
	}
	
	public void paint(Graphics g) {
		r = bounds();
		if(myReset){
			
			drawMyBackground(175,225,true,0.0);
			// Draw the off-screen image
			g.drawImage(myOffImage,30,0,this);
			myReset=false;
		} else if (myBegin){
			drawMySim(g);
			// Draw the off-screen image
			myBegin=false;
		}
	}
	
	public void setvar(double angn,double coefkn,double coefsn,double m1n,double m2n){
		ang=angn;
		coefk=coefkn;
		coefs=coefsn;
		m1=m1n;
		m2=m2n;
		if((oldang != ang) || (oldm1 != m1) || (oldm2 != m2)){
			myReset=true;
			repaint();
		}
		oldang=ang;
		oldm1=m1;
		oldm2=m2;
	}
	
	public void redraw(boolean beginn,boolean reset){
		myBegin = beginn;
		myReset = reset;
		repaint();
	}
	
	public int getColls(){
		return numCollisions;
	}
	 
	public void drawMySim(Graphics g){
		int i;
		int m1x,m2y;
		double myR;
		int newx;
		double theta;
		double step=0.2;
		double t;
		long timeBegin,timeEnd;
		long timeDiff;
		int aint;
		double adis;
		int waitTime=50;
		int checkx,checky;
		double maxFs,maxFsAbs;
		double netForce,netForceAbs;
		
		theta=Math.PI*ang/180.0;
		offg.setFont(new Font("TimesRoman", Font.PLAIN, 12));

		// Check to see if we can overcome static friction
		maxFs=m1*grav*coefs*Math.cos(theta);
		netForce=grav*(m2-m1*Math.sin(theta));
		maxFsAbs=Math.abs(maxFs);
		netForceAbs=Math.abs(netForce);
		if(netForceAbs < maxFsAbs){
			// We cannot overcome static friction, so do not move
			drawMyBackground(175,225,false,0.0);
			offg.setColor(Color.red);
			offg.drawString("Schwerkraftskomponente < Reibung",15,15);
			offg.drawString("Masse bleibt haften",15,30);
			g.drawImage(myOffImage,30,0,this);
		} else if(netForceAbs < 0.1){
			g.setColor(Color.red);
			g.drawString("Nettokraft ist fast 0",15,15);
			g.drawString("Keine sichtbare Bewegung",15,30);
		} else if (netForce >= 0.1){
			a=grav*(m2-m1*Math.sin(theta)-coefk*m1*Math.cos(theta))/(m1+m2);
			aint=(int)(a*100.0);
			adis=((double)(aint))/100.0;
			t=0.0;
			timeBegin=System.currentTimeMillis();
			do {
				newx=(int)((0.5*a*t*t)+0.5);
				myR=(double)(newx);
				m1x=(int)((myR*Math.cos(Math.PI*ang/180.0))+0.5);
				m2y=newx;
				drawMyBackground(175+m1x,225+m2y,false,a);
				offg.setColor(Color.black);
				offg.drawString("a = "+adis+" m/s/s",15,15);
				g.drawImage(myOffImage,30,0,this);
				t=t+step;
				timeEnd=System.currentTimeMillis();
				timeDiff=timeEnd-timeBegin;
				while (timeDiff < waitTime) {
					timeEnd=System.currentTimeMillis();
					timeDiff=timeEnd-timeBegin;
				}
				timeBegin=timeEnd;
			} while (newx < 50);
		} else if(netForce < -0.1){
			a=grav*(m2-m1*Math.sin(theta)+coefk*m1*Math.cos(theta))/(m1+m2);
			aint=(int)(a*100.0);
			adis=((double)(aint))/100.0;
			newx=0;
			t=0.0;
			timeBegin=System.currentTimeMillis();
			checkx=500;
			checky=500;
//			while (newx > -50) {
			do {
				newx=(int)((0.5*a*t*t)+0.5);
				myR=(double)(newx);
				m1x=(int)((myR*Math.cos(Math.PI*ang/180.0))+0.5);
				m2y=newx;
				drawMyBackground(175+m1x,225+m2y,false,a);
				checkx=175+m1x;
				checky=225+m2y;
				offg.setColor(Color.black);
				offg.drawString("a = "+adis+" m/s/s",15,15);
				g.drawImage(myOffImage,30,0,this);
				t=t+step;
				timeEnd=System.currentTimeMillis();
				timeDiff=timeEnd-timeBegin;
				while (timeDiff < waitTime) {
					timeEnd=System.currentTimeMillis();
					timeDiff=timeEnd-timeBegin;
				}
				timeBegin=timeEnd;
			} while ((checky > ymax+30) && (checkx > 25));
		}
	}
		
	public void drawMyBackground(int m1LeftEdge,int m2Center,boolean doHand,double accel){
		int w,h;
		int i;
		int y;
		int xCoords[]={25,350,350,25};
		int yCoords[]={250,250,200,250};
		int xBox[]={100,150,150,100,100};
		int yBox[]={250,250,200,200,250};
		int xDiff;
		int xs1,ys1,xs2,ys2;
		int m2xcen,m2ycen;
		int vx,vy;
		int vxx,vyy;
		double myCos,mySin,myTan;
		double myCos90,mySin90;
		int vecx,vecy;
		int tension;
		double tensiond;
		
		offg.setFont(new Font("TimesRoman", Font.PLAIN, 12));
		myCos=Math.cos(Math.PI*ang/180.0);
		mySin=Math.sin(Math.PI*ang/180.0);
		myCos90=Math.cos(Math.PI*(ang+90.0)/180.0);
		mySin90=Math.sin(Math.PI*(ang+90.0)/180.0);
		myTan=Math.tan(Math.PI*ang/180.0);
		w = r.width;
		h = r.height;
		tensiond=2.0*m2*(grav-accel)/grav;
		tension=(int)(tensiond);
		// Draw white background
		offg.setColor(Color.white);
		offg.fillRect(0,0,w,h);
		// draw plane
		offg.setColor(Color.orange);
		y=(int)(325.0*myTan);
		yCoords[2]=250-y;
		offg.fillPolygon(xCoords,yCoords,4);
		// Draw an arc to show ang on the inclined plane
		offg.setColor(Color.black);
		y=(int)(50.0*myTan);
		offg.drawArc(0,225,50,50,0,(int)ang);
		offg.drawString("phi",60,250-y/4+2);
		// Draw the table top
		offg.setColor(Color.gray);
		offg.fillRect(0,250,351,45);
		// Draw mass on the plane
		offg.setColor(Color.lightGray);
		xBox[0]=(int)(m1LeftEdge*Math.cos(ang*Math.PI/180.0));
		yBox[0]=250-((int)((double)(xBox[0]-xCoords[0])*myTan)); //+0.5));
		xBox[1]=xBox[0]+(int)(60.0*myCos); //+0.5);
		yBox[1]=yBox[0]-(int)(60.0*mySin);
		xBox[2]=xBox[0]+(int)(Math.sqrt(2.0)*60.0*Math.cos(Math.PI*(ang+45.0)/180.0)); //+0.5);
		yBox[2]=yBox[0]-(int)(Math.sqrt(2.0)*60.0*Math.sin(Math.PI*(ang+45.0)/180.0)); //+0.5);
		xBox[3]=xBox[0]+(int)(60.0*myCos90); //+0.5);
		yBox[3]=yBox[0]-(int)(60.0*mySin90); //+0.5);
		xBox[4]=xBox[0];
		yBox[4]=yBox[0];
		offg.fillPolygon(xBox,yBox,5);
		offg.setColor(Color.black);
		offg.drawPolygon(xBox,yBox,5);
		// Draw the force vectors on M1
		//M1g
		offg.setColor(Color.red);
		vx=(xBox[0]+xBox[2])/2;
		vy=(yBox[0]+yBox[2])/2 + 1;
		offg.drawLine(vx,vy,vx,vy+(int)(2*m1));
		offg.drawLine(vx,vy+(int)(2*m1),vx+2,vy+(int)(2*m1)-5);
		offg.drawLine(vx,vy+(int)(2*m1),vx-2,vy+(int)(2*m1)-5);
		offg.drawString("M g",vx+5,vy+(int)(2*m1)+5);
		
		vxx=(int)(2.0*m1*myCos*myCos90);
		vyy=(int)(2.0*m1*myCos*mySin90);
		
		offg.setColor(Color.blue);
		offg.drawString("N",vx+vxx-5,vy-vyy-5);
		drawMyArrow(offg,ang+90.0,vx+vxx,vy-vyy);
		offg.drawLine(vx,vy,vx+vxx,vy-vyy);
		
		offg.setColor(Color.black);
		drawMyArrow(offg,ang-90.0,vx-vxx,vy+vyy);          //
		offg.drawLine(vx,vy,vx-vxx,vy+vyy);
		offg.drawString("M g cos(phi)",vx-vxx+5,vy+vyy+5);  //
		
		vxx=(int)(2.0*m1*mySin*mySin90);
		vyy=(int)(2.0*m1*mySin*myCos90);
		drawMyArrow(offg,ang+180,vx-vxx,vy-vyy);
		offg.drawLine(vx,vy,vx-vxx,vy-vyy);
		offg.drawString("M g sin(phi)",vx-vxx-60,vy-vyy+5);  //
 
		// Now force of friction
		if(coefk > 0.0){
			offg.setColor(Color.red);
			vxx=(int)(2.0*coefk*m1*myCos*myCos);
			vyy=(int)(2.0*coefk*m1*myCos*mySin);
			if(accel > 0.0){
				offg.drawLine(xBox[0],yBox[0],xBox[0]-vxx,yBox[0]+vyy);
				drawMyArrow(offg,ang+180.0,xBox[0]-vxx,yBox[0]+vyy);
				offg.drawString("Fk",xBox[0]-vxx-10,yBox[0]+vyy-3);
			} else if (accel < 0.0){
				offg.drawLine(xBox[1],yBox[1],xBox[1]+vxx,yBox[1]-vyy);
				drawMyArrow(offg,ang,xBox[1]+vxx,yBox[1]-vyy);
				offg.drawString("Fk",xBox[1]+vxx+4,yBox[1]-vyy-6);				
			}
		}
		// Draw the hand
		if(doHand){
			offg.drawImage(handImage,xBox[3]-23,yBox[3]-18,this);
		}
	}
	
	public void drawMyArrow(Graphics g,double theta,int xx,int yy){
		double arrowTheta=158.2;
		double d=5.385;
		int xn,yn;
		// Draw the arrow head
		// Top half
		xn=xx+(int)(d*Math.cos(Math.PI*(theta+arrowTheta)/180.0));
		yn=yy-(int)(d*Math.sin(Math.PI*(theta+arrowTheta)/180.0));
		g.drawLine(xx,yy,xn,yn);
		// Bottom half
		xn=xx+(int)(d*Math.cos(Math.PI*(theta-arrowTheta)/180.0));
		yn=yy-(int)(d*Math.sin(Math.PI*(theta-arrowTheta)/180.0));
		g.drawLine(xx,yy,xn,yn);
	}

}