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POUsing velocity to move rectangle in javascript using processing.js
 

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  1. POUsing velocity to move rectangle in javascript using processing.js
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    <p>I am working on a simple pong clone using javascript and processing.js . I have made classes for the paddles, which are then extended to make a class which will be controlled by the player(s). Currently, I am attempting to implement handling for keyboard input within the player controlled class. My intent is that when <code>w</code> or <code>s</code> is pressed, I update the position of the player's paddle through a velocity represented by a <code>pVector</code> variable within the player class. </p> <p>However, when the corresponding keys are pressed, currently the paddle simply disappears.</p> <p>The script can be seen on jsfiddle <a href="http://jsfiddle.net/ma6rt/9/" rel="nofollow">here</a>, and My code is as follows:</p> <pre><code> // For reference // standard rectangle constructor is: rect(x, y, width, height); class Paddle { //width of paddle float pWidth; //height of paddle float pHeight; //initial paddle x coordinate float x; //initial paddle y coordinate float y; Paddle(float w, float h, float startX, float startY) { //set width paddleWidth = w; //set height paddleHeight = h; //set start x x = startX; //set start y y = startY; } void update() { } void draw() { //draw and fill rectangle with white fill(255) rect(x,y,paddleWidth,paddleHeight) } } class Player extends Paddle { Player(float w, float h, float startX, float startY) { super(w,h,startX,startY); } } class PlayerOne extends Paddle { pVector playerVelocity = (0,0); PlayerOne(float w, float h, float startX, float startY) { super(w,h,startX,startY); } void update() { debugger; if(keyPressed) { if(key == 'w') { y -= playerVelocity.y; } else if(key == 's') { y += playerVelocity.y; } } } } //array list to hold the player paddles ArrayList&lt;Paddle&gt; paddles = new ArrayList&lt;Paddle&gt;(); //middle x and middle y float mx, my, pw, ph; void setup() { mx = width/2; my = height/2; pw = 10; ph = 50; player1 = new PlayerOne(pw,ph,10,10); player2 = new Player(pw,ph,385,10); paddles.add(player1); paddles.add(player2); size(400,400); } void draw() { background(0); fill(100,100,0); // update each paddle added to array list for(Paddle p: paddles) { p.update(); p.draw(); } } </code></pre> <p>What am I doing wrong?</p> <p>UPDATE:</p> <p>I put a breakpoint in with the line <code>debugger</code> after the condition on key press: <code>if(keyPressed)</code> . It seems that if the key is pressed once, it is detected repeatedly on every update for some reason. </p>
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    1. USChristian
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    1. COhave you tried using a javascript debugger? e.g. Firebug addin for Firefox. Really useful for figuring out problems like this. At a quick glance you don't seem to handle things going out of bounds...
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      1. USFloris
    2. COI have really been doing the whole thing through jsfiddle. Would a browser js debugger allow debugging of code run through jsfiddle? My assumption is yes, since I assume a script is just run through the site, so forgive my ignorance if that is a stupid question.
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      1. USChristian
    3. CONevermind, I was able to put a breakpoint in with the line `debugger` after the condition on key press: `if(keyPressed)` . It seems that if the key is pressed once, it is detected repeatedly on every update for some reason.
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      1. USChristian
 

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