import java.awt.*;
import java.awt.event.*;

// Create a circle class that extends the base
// drawing class.
//
// The move() method steps the object according to
// kinematic equations for an object in a constant
// gravitational field.
//
public class Circle extends ObjectToDraw{
  int lastX, lastY,currentX, currentY;
  int drawXInit,drawYInit;
  int radius;

  double g;
  double time=0.0;
  double x,y;
  double VxInit,VyInit;
  double xRightBound,yBottomBound;
  double FrictionLoss;

  boolean  xStop,yStop;
/*---------------------------------------------------*/

  Circle (int centerX, int centerY, int radius,
          int dX, int dY, double grav){
    // super constructor must be called in first line.
    super(centerX,centerY,2*radius,2*radius,dX,dY);

    this.radius = radius;

    drawXInit = drawX = (areaX/2)-radius;
    drawYInit = drawY;

    FrictionLoss = 0.05;
    time=0.0;
    g = grav;// In pixels per sec**2

    VxInit = Vx;
    VyInit = Vy;

    xRightBound  = areaX;
    yBottomBound = areaY;
  }
/*---------------------------------------------------*/
  public void reset(){
    drawX = drawXInit; drawY=drawYInit;
    lastX = drawX; lastY=drawY;
    currentX = drawX; currentY = drawY;

    // Use double value for physical position.
    x=(areaX/2)-radius;
    y=drawY;

    Vx = VxInit;
    Vy = VyInit;

    yStop   = false;
    xStop   = false;

}
/*---------------------------------------------------*/
// This method holds most of the physics.
// The kinematic equations determine the movement of the
// ball in the gravitational field.
//
// Step the objects in both X,Y.
// Include horizontal velocity for optional studies on
// its effects.
//
  public synchronized void move(double deltaT){
    double dt=0.0;
    double ytmp;


    // Horizontal movement has no forces except the
    // approximation of friction at the walls.
    x += deltaT*Vx;

    // Gravitational affects on Y movement
    y += deltaT*Vy + 0.5*g*deltaT*deltaT;
    Vy += g*deltaT;

    if(y >= yBottomBound || x >= xRightBound) {
      yStop = true;
      xStop = true;
    }

    drawY=(int)Math.round(y);
    drawX=(int)Math.round(x);

  }
/*---------------------------------------------------*/
  void clipToAffectedArea( Graphics g, int oldx, int oldy, int newx,
        int newy, int width, int height) {
    int x = Math.min( oldx, newx );
    int y = Math.min( oldy, newy );
    int w = ( Math.max( oldx, newx ) + width ) - x;
    int h = ( Math.max( oldy, newy ) + height ) - y;
    g.clipRect( x, y, w, h );
  }
/*---------------------------------------------------*/
// Override the base class draw method.
  public synchronized void draw(Graphics g) {

    lastX = currentX; lastY = currentY;
    currentX = drawX; currentY = drawY;
    clipToAffectedArea( g, lastX, lastY, currentX,
                         currentY, dx, dy );

    g.setColor(Color.white);
    g.fillRect(0,0,areaX,areaY);

    g.setColor(color);

    // Now draw a solid color circle.
    g.fillOval(drawX,drawY,dx,dy);
    lastX = drawX; lastY=drawY;
 }
}