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audio element not valid

I'm creating a audio player with visualizer.
But currently when I press the input to start the audio player my debug console returns:
Uncaught (in promise) DOMException: Failed to load because no
supported source was found.
What I'm currently doing is setting the whole audio element up in JS / jQuery:
var bins = 512;
var backgroundColour = "#2C2E3B";
var barColour = "#EC1A55";
var floorLevel = 32;
var audioContext;
var audioBuffer;
var audioAnalyserNode;
var initialized = false;
var songText = "";
var textSize;
var freqLookup = [];
var canvasContext;
var isStream = true;
var canvasWidth;
var canvasHeight;
var src;
var audioElement;
var isPlaying = false;
var volume = 1;
function play() {
audioElement = document.createElement('audio');
// Opus support check stuff
var streamEndpoint = 'http://**.**.**.**:8003/stream';
var canPlayOpus = (typeof audioElement.canPlayType === "function" && audioElement.canPlayType('audio/ogg; codecs="opus"') !== "");
if(volume > 1) {
volume = volume / 100;
}
audioElement.src = streamEndpoint;
audioElement.crossOrigin = 'anonymous';
audioElement.volume = volume;
audioElement.play();
isPlaying = true;
setUpCanvas(audioElement);
}
function pause() {
audioElement.pause();
audioElement.currentTime = 0;
audioElement.src = '';
isPlaying = false;
}
function setUpCanvas(audioElement){
try {
initCanvas(document.getElementById("canvas"));
if(typeof audioContext === 'undefined') {
audioContext = new AudioContext();
}
if (audioElement) {
isStream = true;
setupAudioApi(true, audioElement);
}
} catch(e) {
console.log(e);
}
}
function setupAudioApi(isStream, audioElement) {
//var src;
if (isStream){
if(typeof src === 'undefined'){
src = audioContext.createMediaElementSource(audioElement);
audioContext.crossOrigin = "anonymous";
audioAnalyserNode = audioContext.createAnalyser();
audioAnalyserNode.fftSize = bins * 4;
src.connect(audioAnalyserNode);
audioAnalyserNode.connect(audioContext.destination);
}
}
if (!isStream) {
src.start();
}
initialized = true;
initFreqLookupTable();
}
function initCanvas(canvasElement) {
canvasContext = canvasElement.getContext('2d');
canvasElement.width = canvasElement.clientWidth;
canvasElement.height = canvasElement.clientHeight;
canvasWidth = canvasElement.width;
canvasHeight = canvasElement.height;
requestAnimationFrame(paint);
}
function getFreqPoint(start, stop, n, binCount) {
return start * Math.pow(stop / start, n / (binCount - 1));
}
function initFreqLookupTable() {
var lastPoint = 0;
var bins = audioAnalyserNode.frequencyBinCount;
for(var i = 0; i < bins / 2; i++) {
//Scale to perceived frequency distribution
var newFreq = getFreqPoint(20, 20000, i * 2, bins);
var point = Math.floor(bins * newFreq / 20000);
while (point <= lastPoint) {
point++;
}
lastPoint = point;
freqLookup.push(point);
}
}
//Render some fancy bars
function paint() {
requestAnimationFrame(paint);
if(!initialized) {
alert('Er is iets fout gegaan');
return false;
}
canvasContext.clearRect(0, 0, canvasWidth, canvasHeight);
canvasContext.fillStyle = backgroundColour;
canvasContext.fillRect(0, 0, canvasWidth, canvasHeight);
var bins = audioAnalyserNode.frequencyBinCount;
var data = new Uint8Array(bins);
audioAnalyserNode.getByteFrequencyData(data);
canvasContext.fillStyle = barColour;
for(var i = 0; i < bins; i++) {
var point = freqLookup[i];
//Pretty much any volume will push it over 128 so we set that as the bottom threshold
//I suspect I should be doing a logarithmic space for the volume as well
var height = Math.max(0, (data[point] - floorLevel));
//Scale to the height of the bar
//Since we change the base level in the previous operations, 256 should be changed to 160 (i think) if we want it to go all the way to the top
height = (height / (256 - floorLevel)) * canvasHeight * 0.8;
var width = Math.ceil(canvasWidth / ((bins / 2) - 1));
canvasContext.fillRect(i * width, canvasHeight - height, width, height);
}
}
The stream is in audio/mpeg format, it does load when I simply create an audio element in HTML with a src.
Can someone help me clarify and find the solution to the DOMException I'm getting. I have been searching other cases of this error but the fixes there didn't resolve the problem.

Try creating the audio tag like this:
var audio = new Audio('audio_file.mp3');
And try setting the type:
audio.type = "audio/mpeg";
I think that will fix your problem.
This creates an element, identical to the one you use in your code.
I suggest you put an extension on your stream.
I know this way works, and I don't know why the other way doesn't.

JavaScript Variable wont stop reverting back to 0

I'm currently working on a small tile matching game and have made it so that each time you complete the game the variable "bestTime" will store the amount of time you took to complete the session. The variable "bestTimeTxt" will then take the value and display it in text. After you have completed a session a link will appear allowing you to start again. I have put the new text
bestTimeTxt = new Text("Best Time: " + bestTime , "30px Monospace", "#000");
bestTimeTxt.textBaseLine = "top";
bestTimeTxt.x = 500;
bestTimeTxt.y = 100;
outside of the init() function so it shouldn't keep resetting I'm not sure what I am supposed to do as every combination i could think of isn't working.
here is my full code.
I'm also using easeljs for this game
<!DOCTYPE html>
<html>
<head>
<title>Recipe: Drawing a square</title>
<script src="easel.js"></script>
<script type="text/javascript">
var canvas;
var stage;
var squareSide = 70;
var squareOutline = 5;
var max_rgb_color_value = 255;
var gray = Graphics.getRGB(20, 20, 20);
var placementArray = [];
var tileClicked;
var timeAllowable;
var totalMatchesPossible;
var matchesFound;
var txt;
var bestTime = 0;
var bestTimeTxt;
var matchesFoundText;
var squares;
var startingTime;
bestTimeTxt = new Text("Best Time: " + bestTime , "30px Monospace", "#000");
bestTimeTxt.textBaseLine = "top";
bestTimeTxt.x = 500;
bestTimeTxt.y = 100;
function init() {
var rows = 5;
var columns = 6;
var squarePadding = 10;
canvas = document.getElementById('myCanvas');
stage = new Stage(canvas);
var numberOfTiles = rows*columns;
matchesFound = 0;
timeAllowable = 500;
startingTime = timeAllowable;
txt = new Text(timeAllowable, "30px Monospace", "#000");
txt.textBaseline = "top"; // draw text relative to the top of the em box.
txt.x = 500;
txt.y = 0;
stage.addChild(bestTimeTxt);
stage.addChild(txt);
squares = [];
totalMatchesPossible = numberOfTiles/2;
Ticker.init();
Ticker.addListener(window);
Ticker.setPaused(false);
matchesFoundText = new Text("Pairs Found: "+matchesFound+"/"+totalMatchesPossible, "30px Monospace", "#000");
matchesFoundText.textBaseline = "top"; // draw text relative to the top of the em box.
matchesFoundText.x = 500;
matchesFoundText.y = 40;
stage.addChild(matchesFoundText);
setPlacementArray(numberOfTiles);
for(var i=0;i<numberOfTiles;i++){
var placement = getRandomPlacement(placementArray);
if (i % 2 === 0){
var color = randomColor();
}
var square = drawSquare(gray);
square.color = color;
square.x = (squareSide+squarePadding) * (placement % columns);
square.y = (squareSide+squarePadding) * Math.floor(placement / columns);
squares.push(square);
stage.addChild(square);
square.cache(0, 0, squareSide + squarePadding, squareSide + squarePadding);
square.onPress = handleOnPress;
stage.update();
};
}
function drawSquare(color) {
var shape = new Shape();
var graphics = shape.graphics;
graphics.setStrokeStyle(squareOutline);
graphics.beginStroke(gray);
graphics.beginFill(color);
graphics.rect(squareOutline, squareOutline, squareSide, squareSide);
return shape;
}
function randomColor(){
var color = Math.floor(Math.random()*255);
var color2 = Math.floor(Math.random()*255);
var color3 = Math.floor(Math.random()*255);
return Graphics.getRGB(color, color2, color3)
}
function setPlacementArray(numberOfTiles){
for(var i = 0;i< numberOfTiles;i++){
placementArray.push(i);
}
}
function getRandomPlacement(placementArray){
randomNumber = Math.floor(Math.random()*placementArray.length);
return placementArray.splice(randomNumber, 1)[0];
}
function handleOnPress(event){
var tile = event.target;
tile.graphics.beginFill(tile.color).rect(squareOutline, squareOutline, squareSide, squareSide);
if(!!tileClicked === false || tileClicked === tile){
tileClicked = tile;
tileClicked.updateCache("source-overlay");
}else{
if(tileClicked.color === tile.color && tileClicked !== tile){
tileClicked.visible = false;
tile.visible = false;
matchesFound++;
matchesFoundText.text = "Pairs Found: "+matchesFound+"/"+totalMatchesPossible;
if (matchesFound===totalMatchesPossible){
gameOver(true);
}
}else{
tileClicked.graphics.beginFill(gray).rect(squareOutline, squareOutline, squareSide, squareSide);
}
tileClicked.updateCache("source-overlay");
tile.updateCache("source-overlay");
tileClicked = tile;
}
stage.update();
}
function tick() {
secondsLeft = Math.floor((timeAllowable-Ticker.getTime()/1000));
txt.text = secondsLeft;
;
if (secondsLeft <= 0){
gameOver(false);
}
stage.update();
}
function gameOver(win){
Ticker.setPaused(true);
for(var i=0;i<squares.length;i++){
squares[i].graphics.beginFill(squares[i].color).rect(5, 5, 70, 70);
squares[i].onPress = null;
if (win === false){
squares[i].uncache();
}
}
var replayParagraph = document.getElementById("replay");
replayParagraph.innerHTML = "<a href='#' onClick='history.go(0);'>Play Again?</a>";
if (win === true){
matchesFoundText.text = "You win!"
if((startingTime - secondsLeft) > bestTime)
{
bestTime = startingTime - secondsLeft;
bestTimeTxt.text = "Best Time: " + bestTime;
}
}
else
{
txt.text = secondsLeft + "... Game Over";
}
}
function replay(){
init();
}
</script>
</head>
<body onload="init()">
<header id="header">
<p id="replay"></p>
</header>
<canvas id="myCanvas" width="960" height="400"></canvas>
</body>
</html>

In your code, inside gameover method, I see you are using history.go(0) on play again link.
Technically, history.go(0) means to refresh the page and all your variables no matter the scope are set to the initial values.
If you want to retain the best score for the session and continue, use the replay method instead of history.
Updated Code :
replayParagraph.innerHTML = "<a href='#' onClick='replay();'>Play Again?</a>";

0x800a01bd - JavaScript runtime error: Object doesn't support this action

I am reading and trying to do this tutorial:
http://www.sitepoint.com/creating-a-simple-windows-8-game-with-javascript-input-and-sound/
Yesterday, I wrote in this forum with one error, and solved it, but today, I'm in the final one and getting another error.
My default.html file
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>CatapultGame</title>
<!-- WinJS references -->
<link href="//Microsoft.WinJS.1.0/css/ui-light.css" rel="stylesheet" />
<script src="//Microsoft.WinJS.1.0/js/base.js"></script>
<script src="//Microsoft.WinJS.1.0/js/ui.js"></script>
<!-- CatapultGame references -->
<link href="/css/default.css" rel="stylesheet" />
<script src="/js/default.js"></script>
<script src="js/CreateJS/easeljs-0.6.0.min.js"></script>
<script src="js/CreateJS/preloadjs-0.2.0.min.js"></script>
</head>
<body>
<canvas id="gameCanvas"></canvas>
</body>
</html>
and default.js file :
// For an introduction to the Blank template, see the following documentation:
// http://go.microsoft.com/fwlink/?LinkId=232509
(function () {
"use strict";
var app = WinJS.Application;
var activation = Windows.ApplicationModel.Activation;
WinJS.strictProcessing();
var canvas, context, stage;
var bgImage, p1Image, p2Image, ammoImage, p1Lives, p2Lives, title, endGameImage;
var bgBitmap, p1Bitmap, p2Bitmap, ammoBitmap;
var preload;
// calculate display scale factor - original game assets assume 800x480
var SCALE_X = window.innerWidth / 800;
var SCALE_Y = window.innerHeight / 480;
var MARGIN = 25;
var GROUND_Y = 390 * SCALE_Y;
var LIVES_PER_PLAYER = 3;
var player1Lives = LIVES_PER_PLAYER;
var player2Lives = LIVES_PER_PLAYER;
var isShotFlying = false;
var playerTurn = 1;
var playerFire = false;
var shotVelocity;
var MAX_SHOT_POWER = 10;
var GRAVITY = 0.07;
var isAiming = false;
var aimPower = 1;
var aimStart, aimVector;
var FIRE_SOUND_FILE = "/sounds/CatapultFire.wav";
var HIT_SOUND_FILE = "/sounds/BoulderHit.wav";
var EXPLODE_SOUND_FILE = "/sounds/CatapultExplosion.wav";
var LOSE_SOUND_FILE = "/sounds/Lose.wav";
var AIM_SOUND_FILE = "/sounds/RopeStretch.wav";
var WIN_SOUND_FILE = "/sounds/Win.wav";
app.onactivated = function (args) {
if (args.detail.kind === activation.ActivationKind.launch) {
if (args.detail.previousExecutionState !== activation.ApplicationExecutionState.terminated) {
// TODO: This application has been newly launched. Initialize
// your application here.
} else {
// TODO: This application has been reactivated from suspension.
// Restore application state here.
}
args.setPromise(WinJS.UI.processAll());
}
};
function initialize() {
canvas = document.getElementById("gameCanvas");
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
context = canvas.getContext("2d");
canvas.addEventListener("MSPointerUp", endAim, false);
canvas.addEventListener("MSPointerMove", adjustAim, false);
canvas.addEventListener("MSPointerDown", beginAim, false)
**var stage = new createjs.Stage(canvas);** <<========== HERE IS THE ERROR LINE !!!!
// use preloadJS to get sounds and images loaded before starting
preload = new createjs.PreloadJS();
preload.onComplete = prepareGame;
var manifest = [
{ id: "screenImage", src: "images/Backgrounds/gameplay_screen.png" },
{ id: "redImage", src: "images/Catapults/Red/redIdle/redIdle.png" },
{ id: "blueImage", src: "images/Catapults/Blue/blueIdle/blueIdle.png" },
{ id: "ammoImage", src: "images/Ammo/rock_ammo.png" },
{ id: "winImage", src: "images/Backgrounds/victory.png" },
{ id: "loseImage", src: "images/Backgrounds/defeat.png" },
{ id: "blueFire", src: "images/Catapults/Blue/blueFire/blueCatapultFire.png" },
{ id: "redFire", src: "images/Catapults/Red/redFire/redCatapultFire.png" },
{ id: "hitSound", src: HIT_SOUND_FILE },
{ id: "explodeSound", src: EXPLODE_SOUND_FILE },
{ id: "fireSound", src: FIRE_SOUND_FILE },
{ id: "loseSound", src: LOSE_SOUND_FILE },
{ id: "aimSound", src: AIM_SOUND_FILE },
{ id: "winSound", src: WIN_SOUND_FILE }
];
preload.loadManifest(manifest);
}
function prepareGame()
{
// draw Bg first, others appear on top
bgImage = preload.getResult("screenImage").result;
bgBitmap = new createjs.Bitmap(bgImage);
bgBitmap.scaleX = SCALE_X;
bgBitmap.scaleY = SCALE_Y;
stage.addChild(bgBitmap);
// draw p1 catapult
p1Image = preload.getResult("redImage").result;
p1Bitmap = new createjs.Bitmap(p1Image);
p1Bitmap.scaleX = SCALE_X;
p1Bitmap.scaleY = SCALE_Y;
p1Bitmap.x = MARGIN;
p1Bitmap.y = GROUND_Y - p1Image.height * SCALE_Y;
stage.addChild(p1Bitmap);
// draw p2 catapult and flip
p2Image = preload.getResult("blueImage").result;
p2Bitmap = new createjs.Bitmap(p2Image);
p2Bitmap.regX = p2Image.width;
p2Bitmap.scaleX = -SCALE_X; // flip from right edge
p2Bitmap.scaleY = SCALE_Y;
p2Bitmap.x = canvas.width - MARGIN - (p2Image.width * SCALE_X);
p2Bitmap.y = GROUND_Y - (p2Image.height * SCALE_Y);
stage.addChild(p2Bitmap);
// draw the boulder, and hide for the moment
ammoImage = preload.getResult("ammoImage").result;
ammoBitmap = new createjs.Bitmap(ammoImage);
ammoBitmap.scaleX = SCALE_X;
ammoBitmap.scaleY = SCALE_Y;
ammoBitmap.visible = false; // hide until fired
stage.addChild(ammoBitmap);
// player 1 lives
p1Lives = new createjs.Text("Lives Left : " + player1Lives, "20px sans-serif", "red");
p1Lives.scaleX = SCALE_X;
p1Lives.scaleY = SCALE_Y;
p1Lives.x = MARGIN;
p1Lives.y = MARGIN * SCALE_Y;
stage.addChild(p1Lives);
//player 2 lives
p2Lives = new createjs.Text("Lives Left : " + player2Lives, "20px sans-serif", "red");
p2Lives.scaleX = SCALE_X;
p2Lives.scaleY = SCALE_Y;
p2Lives.x = canvas.width - p2Lives.getMeasuredWidth() * SCALE_X - MARGIN;
p2Lives.y = MARGIN * SCALE_Y;
stage.addChild(p2Lives);
// game title
title = new createjs.Text("Catapult Wars", "30px sans-serif", "black");
title.scaleX = SCALE_X;
title.scaleY = SCALE_Y;
title.x = canvas.width / 2 - (title.getMeasuredWidth() * SCALE_X) / 2
title.y = 30 * SCALE_Y;
stage.addChild(title);
stage.update();
startGame();
}
function startGame()
{
Ticker.setInterval(window.requestAnimationFrame);
Ticker.addListener(gameLoop);
}
function gameLoop()
{
update();
draw();
}
function update() {
if (isShotFlying)
{
// shot in the air
ammoBitmap.x += shotVelocity.x;
ammoBitmap.y += shotVelocity.y;
shotVelocity.y += GRAVITY; //apply gravity to the y(height) values only, obviously
if (ammoBitmap.y + ammoBitmap.image.height >= GROUND_Y ||
ammoBitmap.x <= 0 ||
ammoBitmap.x + ammoBitmap.image.width >= canvas.width)
{
// missed
isShotFlying = false; //stop shot
ammoBitmap.visible = false;
playerTurn = playerTurn % 2 + 1; // invert player ( switch between 1 and 2)
}
else if (playerTurn == 1)
{
if (checkHit(p2Bitmap)) {
// Hit
p2Lives.text = "Lives Left : " + --player2Lives;
processHit();
}
}
else if (playerTurn == 2)
{
if (checkHit(p1Bitmap))
{
// Hit
p1Lives.text = "Lives Left : " + --player1Lives;
processHit();
}
}
}
// No current shot, should either player fire ?
else if (playerTurn == 1)
{
// does the player want to fire ?
if (playerFire)
{
playerFire = false;
ammoBitmap.x = p1Bitmap.x + (p1Bitmap.image.width * SCALE_X / 2);
ammoBitmap.y = p1Bitmap.y;
shotVelocity = aimVector;
fireShot();
}
}
else if (playerTurn == 2)
{
// AI automatically fires (randomly on it's turn)
ammoBitmap.x = p2Bitmap.x + (p2Bitmap.image.width * SCALE_X / 2);
ammoBitmap.y = p2Bitmap.y;
shotVelocity = new createjs.Point(
Math.random() * (-4 * SCALE_X) - 3,
Math.random() * (-3 * SCALE_Y) - 1);
fireShot();
}
}
// triggered by MSPointerDown event
function beginAim(event)
{
if (playerTurn == 1)
{
if (!isAiming)
{
aimStart = new createjs.Point(event.x, event.y);
isAiming = true;
}
}
}
// triggered by MSPointerMove event
function adjustAim(event)
{
if (isAiming)
{
var aimCurrent = new createjs.Point(event.x, event.y);
aimVector = calculateAim(aimStart, aimCurrent);
// TODO write text and/or show aiming arrow on screen
Debug.writeln("Aiming..." + aimVector.x + "/" + aimVector.y);
}
}
// triggered by MSPointerUp event
function endAim(event)
{
if (isAiming) {
isAiming = false;
var aimCurrent = new createjs.Point(event.x, event.y);
aimVector = calculateAim(aimStart, aimCurrent);
playerFire = true;
}
}
function calculateAim(start, end)
{
// this only works for player 1
var aim = new createjs.Point(
(end.x - start.x) / 80,
(end.y - start.y) / 80);
aim.x = Math.min(MAX_SHOT_POWER, aim.x); // cap velocity
aim.x = Math.max(0, aim.x); // fire forward only
aim.y = Math.max(-MAX_SHOT_POWER, aim.y);/// cap velocity
aim.y = Math.min(0, aim.y); // fire up only
return aim;
}
function checkHit(target)
{
// EaselJS hit test doesn't factor in scaling
// so use simple bounding box vs center of rock
// get centre of rock
var shotX = ammoBitmap.x + ammoBitmap.image.width / 2;
var shotY = ammoBitmap.y + ammoBitmap.image.height / 2;
// return wether center of rock is in rectangle bounding target player
return (((shotX > target.x) &&
(shotX <= target.x + (target.image.width * SCALE_X)))
&&
((shotY >= target.y) &&
(shotY <= target.y + (target.image.height * SCALE_Y))));
}
function fireShot()
{
playSound(FIRE_SOUND_FILE);
ammoBitmap.visible = true;
isShotFlying = true;
}
function processHit()
{
playSound(EXPLODE_SOUND_FILE);
isShotFlying = false; // stop shot
ammoBitmap.visible = false; // hide shot
playerTurn = playerTurn % 2 + 1; // change player
if ((player1Lives <= 0) || (player2Lives <= 0)) {
endGame();
}
}
function endGame()
{
Ticker.setPaused(true); // stop game loop
// show win/lose graphic
var endGameImage;
if (player1Lives <= 0)
{
playSound(LOSE_SOUND_FILE);
endGameImage = preload.getResult("loseImage").result;
}
else if (player2Lives <= 0)
{
endGameImage = preload.getResult("winImage").result;
playSound(WIN_SOUND_FILE);
}
var endGameBitmap = new createjs.Bitmap(endGameImage);
stage.addChild(endGameBitmap);
endGameBitmap.x = (canvas.width / 2) - (endGameImage.width * SCALE_X / 2);
endGameBitmap.y = (canvas.height / 2) - (endGameImage.height * SCALE_Y / 2);
endGameBitmap.scaleX = SCALE_X;
endGameBitmap.scaleY = SCALE_Y;
stage.update();
}
function draw() {
// EaselJS allows for easy updates
stage.update();
}
function playSound(path)
{
var sound = document.createElement("audio");
sound.src = path;
sound.autoplay = true;
}
app.oncheckpoint = function (args) {
// TODO: This application is about to be suspended. Save any state
// that needs to persist across suspensions here. You might use the
// WinJS.Application.sessionState object, which is automatically
// saved and restored across suspension. If you need to complete an
// asynchronous operation before your application is suspended, call
// args.setPromise().
};
document.addEventListener("DOMContentLoaded", initialize, false);
app.start();
})();
And there is the problem: when I'm trying to build this game, I'm getting error like this:
0x800a01bd - JavaScript runtime error: Object doesn't support this action
in the marked place in my code
Thanks for any help :)

Three problems, I report them from previous comments:
easeljs not present in the correct folder
mages/Catapults/Red/redFire/redC‌​atapultFire.png missing
change var stage = new createjs.Stage(canvas); to stage = new createjs.Stage(canvas); you don't have to instantiate that variable as reported in the tutorial (http://www.sitepoint.com/creating-a-simple-windows-8-game-with-javascript-game-basics-createjseaseljs/)
And close this other related question (https://stackoverflow.com/a/16101960/975520), I think is solved by posting your solution as answer.

Box2DWeb - Adding and Removing Body in the world

I have the following code in Box2D, I want to move my dynamic body to the point where the mouse is click. Also in the future i want to be able to remove the dynamic body, I am not able to find anything equivalent to world.DeleteBody(...). Please Help.
var world;
var b2Vec2 = Box2D.Common.Math.b2Vec2
, b2BodyDef = Box2D.Dynamics.b2BodyDef
, b2Body = Box2D.Dynamics.b2Body
, b2FixtureDef = Box2D.Dynamics.b2FixtureDef
, b2Fixture = Box2D.Dynamics.b2Fixture
, b2World = Box2D.Dynamics.b2World
, b2MassData = Box2D.Collision.Shapes.b2MassData
, b2PolygonShape = Box2D.Collision.Shapes.b2PolygonShape
, b2CircleShape = Box2D.Collision.Shapes.b2CircleShape
, b2DebugDraw = Box2D.Dynamics.b2DebugDraw
;
var canvas = document.getElementById("canvas");
var context = canvas.getContext("2d");
var mouseX, mouseY, isMouseDown;
var bBallBody, bBallbodyDef;
function init() {
world = new b2World(
new b2Vec2(0, 10) //gravity
, true //allow sleep
);
setupWorld() ;
//setup debug draw
var debugDraw = new b2DebugDraw();
debugDraw.SetSprite(document.getElementById("canvas").getContext("2d"));
debugDraw.SetDrawScale(1.0);
debugDraw.SetFillAlpha(0.3);
debugDraw.SetLineThickness(1.0);
debugDraw.SetFlags(b2DebugDraw.e_shapeBit | b2DebugDraw.e_jointBit);
world.SetDebugDraw(debugDraw);
window.setInterval(update, 1000 / 60);
};
function setupWorld() {
setupGround();
addBouncingBall();
}
function setupGround() {
var fixDef = new b2FixtureDef;
fixDef.density = 1.0;
fixDef.friction = 0.5;
fixDef.restitution = 0.2;
var bodyDef = new b2BodyDef;
//create ground
bodyDef.type = b2Body.b2_staticBody;
bodyDef.position.x = 300;
bodyDef.position.y = 400;
fixDef.shape = new b2PolygonShape;
fixDef.shape.SetAsBox(290, 10);
world.CreateBody(bodyDef).CreateFixture(fixDef);
}
function addBouncingBall() {
var fixDef = new b2FixtureDef;
fixDef.density = 1.0;
fixDef.friction = 1.0;
fixDef.restitution = 0.1;
var bBallbodyDef = new b2BodyDef;
bBallbodyDef.type = b2Body.b2_dynamicBody;
fixDef.shape = new b2CircleShape(Math.random() + 30);
bBallbodyDef.position.x = Math.random() * 300;
bBallbodyDef.position.y = Math.random() * 300;
bBallBody = world.CreateBody(bBallbodyDef).CreateFixture(fixDef);
console.log(bBallBody.m_body.GetPosition().x);
};
document.addEventListener("mousedown", handleMouseMove, true);
function handleMouseMove(e) {
isMouseDown = true;
mouseX = e.clientX;
mouseY = e.clientY;
};
function update() {
if(isMouseDown)
{
for (b = world.GetBodyList() ; b; b = b.GetNext()) {
if (b.GetType() == b2Body.b2_dynamicBody) {
console.log(b.x, b.y);
b.x = 100;
b.y = 100;
}
}
isMouseDown = false;
}
world.Step(1 / 60, 10, 10);
world.DrawDebugData();
world.ClearForces();
};
Update:
Deletion of an object from the world is done as follows,
Create a Timer to Schdule the deletion of the object.
window.setInterval(removeObjScheduledForRemoval, 1000/90);
Collect the objects to be deleted in a Array.
var bricksScheduledForRemoval = Array();
var index = -1;
function removeObjScheduledForRemoval()
{
for(var i = 0; i <= index; i++){
world.DestroyBody(bricksScheduledForRemoval[i]);
bricksScheduledForRemoval[i] = null;
}
bricksScheduledForRemoval = Array();
index = -1;
}
The complete code is available here,
http://box2dinabox.blogspot.in/2012/07/the-completed-bananamonkey-game.html

The documentation for box2dweb is nowhere near as comprehensive as it is for the original C version, so consider searching for "box2d" instead of "box2dweb". Also, looking into the source and searching for the spelling of certain methods could be helpful. Or just look into the box2d flash documentation. Basically, box2dweb has the methods DestroyJoint and DestroyBody.
For more considerations, this could be helpful: http://www.iforce2d.net/b2dtut/removing-bodies

You can remove the body or change the static body to dynamic as this game example does.
http://pixsansar.com/box2dweb-jumping-and-puzzle-ball-level4
Box2dweb has removebody or changeBodyType option, see the source code of it.

box2dweb raycast

I am trying to get the distance between my character and the ground, I have found something that looks like it should do what I want but it has been written for another version of box2d.
Original:
float targetHeight = 3;
float springConstant = 100;
//make the ray at least as long as the target distance
b2Vec2 startOfRay = m_hovercarBody->GetPosition();
b2Vec2 endOfRay = m_hovercarBody->GetWorldPoint( b2Vec2(0,-5) );
overcarRayCastClosestCallback callback;
m_world->RayCast(&callback, startOfRay, endOfRay);
if ( callback.m_hit ) {
float distanceAboveGround = (startOfRay - callback.m_point).Length();
//dont do anything if too far above ground
if ( distanceAboveGround < targetHeight ) {
float distanceAwayFromTargetHeight = targetHeight - distanceAboveGround;
m_hovercarBody->ApplyForce( b2Vec2(0,springConstant*distanceAwayFromTargetHeight),
m_hovercarBody->GetWorldCenter() );
}
}
I have tried to change it to what I think it should be but it doesn't even call the callback.
var targetHeight = 3;
var springConstant = 100;
//make the ray at least as long as the target distance
startOfRay = new b2Vec2(m_hovercarBody.GetPosition());
endOfRay = new b2Vec(m_hovercarBody.GetWorldPoint( b2Vec2(0,-5)));
function callback(raycast){
if ( raycast.m_hit ) {
var distanceAboveGround = (startOfRay - raycast.m_point).Length();
//dont do anything if too far above ground
if ( distanceAboveGround < targetHeight ) {
var distanceAwayFromTargetHeight = targetHeight - distanceAboveGround;
m_hovercarBody.ApplyForce( b2Vec2(0,springConstant*distanceAwayFromTargetHeight),
m_hovercarBody.GetWorldCenter() );
}
}
}
m_world.RayCast(callback, startOfRay, endOfRay);
Any idea how to convert it to work with box2dweb?
Thanks

It might be that the original bit of code was written for a platform where the coordinate system works differently.
In a Canvas element, the coordinate system starts from the top left corner, meaning that m_hovercarBody.GetWorldPoint( b2Vec2(0,-5)) is checking for a point above the character, rather than below.
I'm not sure about the rest of the code but try changing that to m_hovercarBody.GetWorldPoint( b2Vec2(0,5)) and see what happens.
EDIT:
I think actually the problem is with the way you've structured your callback. Looking up the reference for the Raycast function would reveal more.
(The Javascript version of Box2D you're using is an automatic port of the Actionscript one. Given the two have fairly similar syntax, you can use the reference for Flash.)
The original code you posted seems to be C++, but I don't know much about its syntax. It seems there's some sort of class that does the raycasting (overcarRayCastClosestCallback). You can either look for that, or try and build your own callback function according to the first link I posted. It would be something along the lines of:
function customRaycastCallback(fixture, normal, fraction) {
// you can, for instance, check if fixture belongs to the ground
// or something else, then handle things accordingly
if( /* fixture belongs to ground */ ) {
// you've got the fraction of the original length of the raycast!
// you can use this to determine the distance
// between the character and the ground
return fraction;
}
else {
// continue looking
return 1;
}
}

Try running this on your browser. I coded this when I was learning sensor and RAYCAST in Box2Dweb. Hope it helps.
<html>
<head>
<title>Box2dWeb Demo</title>
</head>
<body>
<canvas id="canvas" width="600" height="420" style="background-color:#333333;" ></canvas>
<div id="cc" style="position:absolute; right:0; top:100px; width:500px; height:50px; margin:0;"></div>
</body>
<script type="text/javascript" src="Box2dWeb-2.1.a.3.js"></script>
<script type="text/javascript" src="jquery-1.7.2.js"></script>
<script type="text/javascript">
var b2Vec2 = Box2D.Common.Math.b2Vec2
, b2BodyDef = Box2D.Dynamics.b2BodyDef
, b2Body = Box2D.Dynamics.b2Body
, b2FixtureDef = Box2D.Dynamics.b2FixtureDef
, b2World = Box2D.Dynamics.b2World
, b2PolygonShape = Box2D.Collision.Shapes.b2PolygonShape
, b2CircleShape = Box2D.Collision.Shapes.b2CircleShape
, b2ContactFilter = Box2D.Dynamics.b2ContactFilter
, b2MouseJointDef = Box2D.Dynamics.Joints.b2MouseJointDef
, b2DebugDraw = Box2D.Dynamics.b2DebugDraw
, b2Fixture = Box2D.Dynamics.b2Fixture
, b2AABB = Box2D.Collision.b2AABB
, b2WorldManifold = Box2D.Collision.b2WorldManifold
, b2ManifoldPoint = Box2D.Collision.b2ManifoldPoint
, b2RayCastInput = Box2D.Collision.b2RayCastInput
, b2RayCastOutput = Box2D.Collision.b2RayCastOutput
, b2Color = Box2D.Common.b2Color;
var world = new b2World(new b2Vec2(0,10), true);
var canvas = $('#canvas');
var context = canvas.get(0).getContext('2d');
//box
var bodyDef = new b2BodyDef;
bodyDef.type = b2Body.b2_dynamicBody;
bodyDef.position.Set(9,7);
bodyDef.userData = 'box';
var fixDef = new b2FixtureDef;
fixDef.filter.categoryBits = 1;
fixDef.density = 10.0;
fixDef.friction = 0.5;
fixDef.restitution = .5;
fixDef.shape = new b2PolygonShape;
fixDef.shape.SetAsBox(1,5);
var box1 = world.CreateBody(bodyDef);
box1.CreateFixture(fixDef);
//circle
var bodyDef2 = new b2BodyDef;
bodyDef2.type = b2Body.b2_dynamicBody;
bodyDef2.position.Set(4,8);
bodyDef2.userData = 'obj';
var fixDef2 = new b2FixtureDef;
fixDef2.filter.categoryBits = 2;
fixDef2.filter.maskBits = 13;
fixDef2.density = 10.0;
fixDef2.friction = 0.5;
fixDef2.restitution = .2;
fixDef2.shape = new b2CircleShape(1);
//circlesensor
var cc = new b2FixtureDef;
cc.shape = new b2CircleShape(2);
cc.shape.SetLocalPosition(new b2Vec2(0 ,0));
cc.density = 0;
cc.isSensor = true;
cc.filter.categoryBits = 8;
var wheel = world.CreateBody(bodyDef2);
wheel.CreateFixture(fixDef2);
wheel.CreateFixture(cc);
//create a ground
var holderDef = new b2BodyDef;
holderDef.type = b2Body.b2_staticBody;
holderDef.userData = "ground";
holderDef.position.Set(10, 14);
var fd = new b2FixtureDef;
fd.filter.categoryBits = 4;
fd.shape = new b2PolygonShape;
fd.shape.SetAsBox(10,1);
var ground = world.CreateBody(holderDef);
ground.CreateFixture(fd);
//create another static body
var holderDef = new b2BodyDef;
holderDef.type = b2Body.b2_staticBody;
holderDef.position.Set(10, 20);
var temp = world.CreateBody(holderDef);
temp.CreateFixture(fd);
var c=0;
$(window).keydown(function(e) {
$('#aa').html(++c);
code = e.keyCode;
if(c==1) {
if(code == 38 && onground)
wheel.SetLinearVelocity(new b2Vec2(0,-10));
if(code == 39)
wheel.ApplyForce(new b2Vec2(1000,0), box1.GetWorldPoint(new b2Vec2(0,0)));
if(code == 37)
wheel.ApplyForce(new b2Vec2(-1000,0), box1.GetWorldPoint(new b2Vec2(0,0)));
}
});
$(window).keyup(function(e) {
c=0;
});
var listener = new Box2D.Dynamics.b2ContactListener;
listener.BeginContact = function(contact) {
if(contact.GetFixtureA().GetBody().GetUserData()== 'obj' || contact.GetFixtureB().GetBody().GetUserData()== 'obj' ) // think about why we don't use fixture's userData directly.
onground = true;// don't put 'var' here!
fxA=contact.GetFixtureA();
fxB=contact.GetFixtureB();
sA=fxA.IsSensor();
sB=fxB.IsSensor();
if((sA && !sB) || (sB && !sA)) {
if(sA) {
$('#cc').prepend(contact.GetFixtureB().GetBody().GetUserData() + ' is in the viscinity of body '+contact.GetFixtureA().GetBody().GetUserData()+'<br>');
}
else {
$('#cc').prepend(contact.GetFixtureA().GetBody().GetUserData() + ' is in the viscinity of body '+contact.GetFixtureB().GetBody().GetUserData()+'<br>');
}
}
}
listener.EndContact = function(contact) {
if (contact.GetFixtureA().GetBody().GetUserData()== 'obj' || contact.GetFixtureB().GetBody().GetUserData()== 'obj' )
onground = false;
}
var debugDraw = new b2DebugDraw();
debugDraw.SetSprite ( document.getElementById ("canvas").getContext ("2d"));
debugDraw.SetDrawScale(30); //define scale
debugDraw.SetAlpha(1);
debugDraw.SetFillAlpha(.3); //define transparency
debugDraw.SetLineThickness(1.0);
debugDraw.SetFlags(b2DebugDraw.e_shapeBit | b2DebugDraw.e_jointBit);
world.SetDebugDraw(debugDraw);
window.setInterval(update,1000/60);
//mouse
var mouseX, mouseY, mousePVec, isMouseDown, selectedBody, mouseJoint;
var canvasPosition = getElementPosition(document.getElementById("canvas"));
document.addEventListener("mousedown", function(e) {
isMouseDown = true;
handleMouseMove(e);
document.addEventListener("mousemove", handleMouseMove, true);
}, true);
document.addEventListener("mouseup", function() {
document.removeEventListener("mousemove", handleMouseMove, true);
isMouseDown = false;
mouseX = undefined;
mouseY = undefined;
}, true);
function handleMouseMove(e) {
mouseX = (e.clientX - canvasPosition.x) / 30;
mouseY = (e.clientY - canvasPosition.y) / 30;
};
function getBodyAtMouse() {
mousePVec = new b2Vec2(mouseX, mouseY);
var aabb = new b2AABB();
aabb.lowerBound.Set(mouseX - 0.001, mouseY - 0.001);
aabb.upperBound.Set(mouseX + 0.001, mouseY + 0.001);
// Query the world for overlapping shapes.
selectedBody = null;
world.QueryAABB(getBodyCB, aabb);
return selectedBody;
}
function getBodyCB(fixture) {
if(fixture.GetBody().GetType() != b2Body.b2_staticBody) {
if(fixture.GetShape().TestPoint(fixture.GetBody().GetTransform(), mousePVec)) {
selectedBody = fixture.GetBody();
return false;
}
}
return true;
}
//at global scope
var currentRayAngle = 0;
var input = new b2RayCastInput();
var output = new b2RayCastOutput();
var b = new b2BodyDef();
var f = new b2FixtureDef();
var closestFraction = 1;
var intersectionNormal = new b2Vec2(0,0);
var intersectionPoint = new b2Vec2();
rayLength = 25; //long enough to hit the walls
var p1 = new b2Vec2( 11, 7 ); //center of scene
var p2 = new b2Vec2();
var normalEnd = new b2Vec2();
function update() {
if(isMouseDown && (!mouseJoint)) {
var body = getBodyAtMouse();
if(body) {
var md = new b2MouseJointDef();
md.bodyA = world.GetGroundBody();
md.bodyB = body;
md.target.Set(mouseX, mouseY);
md.collideConnected = true;
md.maxForce = 300.0 * body.GetMass();
mouseJoint = world.CreateJoint(md);
body.SetAwake(true);
}
}
if(mouseJoint) {
if(isMouseDown) {
mouseJoint.SetTarget(new b2Vec2(mouseX, mouseY));
} else {
world.DestroyJoint(mouseJoint);
mouseJoint = null;
}
}
world.Step(1 / 60, 10, 10);
world.DrawDebugData();
world.ClearForces();
world.SetContactListener(listener);
ray();
};
function ray() {
//in Step() function
var k = 360/20;
var t = k/60;
var DEGTORAD = Math.PI/180;
currentRayAngle += t * DEGTORAD; //one revolution every 20 seconds
//console.log(currentRayAngle*(180/Math.PI));
//calculate points of ray
p2.x = p1.x + rayLength * Math.sin(currentRayAngle);
p2.y = p1.y + rayLength * Math.cos(currentRayAngle);
input.p1 = p1;
input.p2 = p2;
input.maxFraction = 1;
closestFraction = 1;
var b = new b2BodyDef();
var f = new b2FixtureDef();
for(b = world.GetBodyList(); b; b = b.GetNext()) {
for(f = b.GetFixtureList(); f; f = f.GetNext()) {
if(!f.RayCast(output, input))
continue;
else if(output.fraction < closestFraction) {
closestFraction = output.fraction;
intersectionNormal = output.normal;
}
}
}
intersectionPoint.x = p1.x + closestFraction * (p2.x - p1.x);
intersectionPoint.y = p1.y + closestFraction * (p2.y - p1.y);
normalEnd.x = intersectionPoint.x + intersectionNormal.x;
normalEnd.y = intersectionPoint.y + intersectionNormal.y;
context.strokeStyle = "rgb(255, 255, 255)";
context.beginPath(); // Start the path
context.moveTo(p1.x*30,p1.y*30); // Set the path origin
context.lineTo(intersectionPoint.x*30, intersectionPoint.y*30); // Set the path destination
context.closePath(); // Close the path
context.stroke();
context.beginPath(); // Start the path
context.moveTo(intersectionPoint.x*30, intersectionPoint.y*30); // Set the path origin
context.lineTo(normalEnd.x*30, normalEnd.y*30); // Set the path destination
context.closePath(); // Close the path
context.stroke(); // Outline the path
}
//helpers
//http://js-tut.aardon.de/js-tut/tutorial/position.html
function getElementPosition(element) {
var elem=element, tagname="", x=0, y=0;
while((typeof(elem) == "object") && (typeof(elem.tagName) != "undefined")) {
y += elem.offsetTop;
x += elem.offsetLeft;
tagname = elem.tagName.toUpperCase();
if(tagname == "BODY")
elem=0;
if(typeof(elem) == "object") {
if(typeof(elem.offsetParent) == "object")
elem = elem.offsetParent;
}
}
return {x: x, y: y};
}
</script>
</html>

Here's a Raycast in Box2dWeb that I got working:
var p1 = new b2Vec2(body.GetPosition().x, body.GetPosition().y); //center of scene
var p2 = new b2Vec2(body.GetPosition().x, body.GetPosition().y + 5); //center of scene
world.RayCast(function(x){
console.log("You've got something under you");
}, p1,p2);