// Zorah Fung, CSE 142
// Creates an animation of a ball falling from gravity

import java.awt.*;

public class BallDemo {
  public static final double GRAVITY = 9.81;  
 
  public static void main(String[] args) {
      DrawingPanel panel = new DrawingPanel(400, 600);
      Graphics g = panel.getGraphics();
      int initX = 100;
      int initY = 100;
      int initV = 24;
      
      int initX2 = 200;
      int initY2 = 50;
      int initV2 = 30;
      
      for (double t = 0; t < 10; t+= 0.05) {
         double dis = displacement(initV, GRAVITY, t);
         g.setColor(Color.RED);
         g.fillOval(initX, initY + (int) dis, 50, 50);
         
         double dis2 = displacement(initV2, GRAVITY, t);
         g.setColor(Color.BLUE);
         g.fillOval(initX2, initY2 + (int) dis2, 50, 50);
         
         panel.sleep(50);
         panel.clear();
      }     
   }
   
   // Given an initial velocity and acceleration an object, returns the displacement
   // the object at time t
   public static double displacement(double v0, double a, double t) {
      return v0 * t + 0.5 * a * t * t;
   }
}