// Bouncing ball simulation

// Variables
int time;
int ballX = 200;
int ballY = 150;
int ball1Width = 30;
int ball1Red = 255;
int ball1Green = 255;
int ball1Blue = 255;

int ball2X = 50;
int ball2Y = 50;
int ball2Width = 45;
int ball2Red = 255;
int ball2Green = 255;
int ball2Blue = 255;
int moveAmount2 = 1;
int fallAmount2 = 5; 

int moveAmount = 2;
int fallAmount = 1;
int windowWidth = 600;
int windowHeight = 400;

void setup()
{
  size(windowWidth, windowHeight);
  smooth(); // get rid of jagged edges
  time = 0;
}

void draw ()
{
  // Draw ball at current position
  background(150);
  drawBallOne();
  drawBallTwo();
  time = time + 1; // Update clock
}

void drawBallOne()
{
  fill(ball1Red, ball1Green, ball1Blue);
  ellipse(ballX, ballY, ball1Width, ball1Width);
  
  if (time % 50 == 0)
  {
    // Accelerate fall every 50th time step
    fallAmount = fallAmount + 1;
    if (fallAmount > 10)
    {
      fallAmount = 10;
    }
  }
  
  // Move ball for next call to draw()
  ballX = ballX + moveAmount;
  ballY = ballY + fallAmount;
  
  // Make sure ball doesn't move offscreen
  int distanceToRightEdge = windowWidth - ballX;
  int distanceToLeftEdge = ballX;
  if (distanceToLeftEdge < 15 || distanceToRightEdge < 15)
  {
    // Reverse direction
    moveAmount = -1 * moveAmount;
  }
  
  int distanceToBottom = windowHeight - ballY;
  int distanceToTop = ballY;
  if (distanceToTop < 15 || distanceToBottom < 15)
  {
    fallAmount = -1 * fallAmount;
    
    // Change ball color
    ball1Red = (int)random(256);
    ball1Green = (int)random(256);
    ball1Blue = (int)random(256);
  }
}

void drawBallTwo()
{
  fill(ball2Red, ball2Green, ball2Blue);
  ellipse(ball2X, ball2Y, ball2Width, ball2Width);
  
  // Move ball for next call to draw()
  ball2X = ball2X + moveAmount2;
  ball2Y = ball2Y + fallAmount2;
  
  // Make sure ball doesn't move offscreen
  int distanceToRightEdge = windowWidth - ball2X;
  int distanceToLeftEdge = ball2X;
  if (distanceToLeftEdge < 15 || distanceToRightEdge < 15)
  {
    // Reverse direction
    moveAmount2 = -1 * moveAmount2;
  }
  
  int distanceToBottom = windowHeight - ball2Y;
  int distanceToTop = ball2Y;
  if (distanceToTop < 15 || distanceToBottom < 15)
  {
    fallAmount2 = -1 * fallAmount2;
    
    // Change ball color
    ball2Red = (int)random(256);
    ball2Green = (int)random(256);
    ball2Blue = (int)random(256);
  }
}