topical media & game development
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#javascript-processing-example-topic-motion-collision.htm / htm



  <!DOCTYPE html>
  <html><head>
  <script src="javascript-processing-example-processing.js"></script>
  <script src="javascript-processing-example-init.js"></script>
  <link rel="stylesheet" href="javascript-processing-example-style.css">
  </head><body><h1><a href="http://ejohn.org/blog/processingjs/">Processing.js</a></h1>
  <h2>Collision</h2>
  
  <p>Move the mouse up and down to move the paddle.</p>
  
  <p><a href="http://processing.org/learning/topics/collision.html"><b>Original Processing.org Example:</b> Collision</a><br>
  <script type="application/processing">
  // 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);  
  }
  </script><canvas width="200" height="200"></canvas></p>
  <div style="overflow: hidden; height: 0px; width: 0px;"></div>
  
  <pre><b>// All Examples Written by <a href="http://reas.com/">Casey Reas</a> and <a href="http://benfry.com/">Ben Fry</a>
  // unless otherwise stated.</b>
  // 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 &gt; 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 
       &amp;&amp; ball_y &gt; paddle_y - paddle_height - ball_size 
       &amp;&amp; ball_y &lt; paddle_y + paddle_height + ball_size) {
      ball_dir *= -1;
      if(mouseY != pmouseY) {
        dy = (mouseY-pmouseY)/2.0;
        if(dy &gt;  5) { dy =  5; }
        if(dy &lt; -5) { dy = -5; }
      }
    } 
    
    // If ball hits paddle or back wall, reverse direction
    if(ball_x &lt; ball_size &amp;&amp; ball_dir == -1) {
      ball_dir *= -1;
    }
    
    // If the ball is touching top or bottom edge, reverse direction
    if(ball_y &gt; height-ball_size) {
      dy = dy * -1;
    }
    if(ball_y &lt; 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);  
  }</pre>
  </body></html>
[] readme course(s) preface I 1 2 II 3 4 III 5 6 7 IV 8 9 10 V 11 12 afterthought(s) appendix reference(s) example(s) resource(s) _

(C) Æliens 20/2/2008

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