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

import java.awt.*;
import java.util.*;

public class BallDemo {
   public static final double GRAVITY = 9.81;
   
   public static void main(String[] args) {
      Scanner console = new Scanner(System.in);
      
      int ballX = 100;
      int ballY = 100;
      System.out.print("Ball 1 Initial velocity? ");
      int ballV0 = console.nextInt();
      
      int ball2X = 200;
      int ball2Y = 50;
      System.out.print("Ball 2 Initial velocity? ");
      int ball2V0 = console.nextInt();
      
      DrawingPanel panel = new DrawingPanel(400, 600);
      Graphics g = panel.getGraphics();
      
      for (double t = 0; t < 10; t+= 0.05) {
         double dis = displacement(ballV0, GRAVITY, t);
         g.setColor(Color.RED);
         g.fillOval(ballX, ballY + (int) dis, 50, 50);
         
         double dis2 = displacement(ball2V0, GRAVITY, t);
         g.setColor(Color.BLUE);
         g.fillOval(ball2X, ball2Y + (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;
   }
}