float ball_x;
float ball_y;
float ball_dir = 1;
float ball_size = 5;
float dy = 0;

int paddle_width = 20;
int paddle_height = 100;
int dist_wall = 60;
void setup() {
  size(800, 600);
  rectMode(CENTER);
  rectMode(RADIUS);
  ellipseMode(CENTER);
  ellipseMode(RADIUS);
  noStroke();
  smooth();
  ball_y = height/2;
  ball_x = 1;
}
void draw() {
  background(51);
  ball_x += ball_dir * 5.0;
  ball_y += dy;

  if(ball_x > width+ball_size) {
    ball_x = -width/2 - ball_size;
    ball_y = random(0, height);
    dy = 0;
  }
  float paddle_y = constrain(mouseY, paddle_height, height - paddle_height);
  float py = width-dist_wall-paddle_width-ball_size;
  if(ball_x == py && ball_y > paddle_y - paddle_height - ball_size && ball_y < paddle_y + paddle_height + ball_size) {
    ball_dir *= -1;
    if(mouseY != pmouseY) {
      dy = (mouseY-pmouseY)/2.0;
      if(dy > 20) {dy = 20;}
      if(dy < -20) {dy = -20;}
    }
  }
  if(ball_x < ball_size && ball_dir == -1)
  {
    ball_dir *= -1;
  }
  if(ball_y > height-ball_size) {
    dy = dy * -1;
  }
  if(ball_y < ball_size) {
    dy = dy * -1;
  }
  fill(255);
  ellipse(ball_x, ball_y,ball_size,ball_size);
  fill(153);
  rect(width-dist_wall, paddle_y, paddle_width, paddle_height);
}