a port of the Processing Visualization Language

Collision

Move the mouse up and down to move the paddle.

Original Processing.org Example: Collision

// All Examples Written by Casey Reas and Ben Fry

// unless otherwise stated.

// Global variables for the ball

float ball_x;

float ball_y;

float ball_dir = 1;

float ball_size = 5;  // Radius

float dy = 0;  // Direction



// Global variables for the paddle

int paddle_width = 5;

int paddle_height = 20;



int dist_wall = 15;



void setup()

{

  size(200, 200);

  rectMode(CENTER_RADIUS);

  ellipseMode(CENTER_RADIUS);

  noStroke();

  smooth();

  ball_y = height/2;

  ball_x = 1;

}



void draw() 

{

  background(51);

  

  ball_x += ball_dir * 1.0;

  ball_y += dy;

  if(ball_x > width+ball_size) {

    ball_x = -width/2 - ball_size;

    ball_y = random(0, height);

    dy = 0;

  }

  

  // Constrain paddle to screen

  float paddle_y = constrain(mouseY, paddle_height, height-paddle_height);



  // Test to see if the ball is touching the paddle

  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 >  5) { dy =  5; }

      if(dy < -5) { dy = -5; }

    }

  } 

  

  // If ball hits paddle or back wall, reverse direction

  if(ball_x < ball_size && ball_dir == -1) {

    ball_dir *= -1;

  }

  

  // If the ball is touching top or bottom edge, reverse direction

  if(ball_y > height-ball_size) {

    dy = dy * -1;

  }

  if(ball_y < ball_size) {

    dy = dy * -1;

  }



  // Draw ball

  fill(255);

  ellipse(ball_x, ball_y, ball_size, ball_size);

  

  // Draw the paddle

  fill(153);

  rect(width-dist_wall, paddle_y, paddle_width, paddle_height);  

}
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