HTML5 Canvas Game- Disappearing Elements

HTML5 Canvas Game- Disappearing Elements

By : user2951366
Date : November 18 2020, 01:01 AM
wish help you to fix your issue You've forgotten to declare the leftDown,upDown,downDown,rightDown variables so your update() fails when trying to use rightdown
Fix: declare those variables:
code :
var leftDown,upDown,downDown,rightDown;

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Build a simple HTML5/canvas 2D game. Game engine recommended to use?

Build a simple HTML5/canvas 2D game. Game engine recommended to use?

By : Roman Hryhorchuk
Date : March 29 2020, 07:55 AM
HTML5 Canvas (Drawing (Rectangle) Keeps Disappearing)

HTML5 Canvas (Drawing (Rectangle) Keeps Disappearing)

By : liteheaded
Date : March 29 2020, 07:55 AM
will be helpful for those in need how's it going? , You have a statement to clear canvas
code :
ctx.clearRect(0, 0, canvas.width, canvas.height);
HTML5 canvas game won't work when applying margins to canvas

HTML5 canvas game won't work when applying margins to canvas

By : Shyam T
Date : March 29 2020, 07:55 AM
Does that help Because you move the canvas, the hit detection code is off because it uses the pageX,pageY values which are values relative to the page. You can get positions relative to the canvas itself by using the offsetX,offsetY values which should get you better hit detection without have to do extra calculations
code :
function btnClick(e) {
    // Variables for storing mouse position on click
    var mx = e.offsetX,
    my = e.offsetY;
HTML5 Canvas + js game | Reset game on death changes the game speeds up?

HTML5 Canvas + js game | Reset game on death changes the game speeds up?

By : jhed
Date : March 29 2020, 07:55 AM
wish of those help Overall I would recommend re-factoring this code so your reset function doesn't re-create so many objects. Basically the reset function is just re-creating a bulk of the game logic.
The specific issue you identified appears to be coming from the fact that you call setInterval on each reset without clearing the previous interval. See the code below with the minimal changes to prevent this issue.
code :
var windowx,

var drawObjects;
var keyState;

var mainloop;
var animFrame;

var reset = function() {

    // Remove our old game loop

    //get canvas and set height and width
    canvas = document.getElementById('canvas');
    canvas.setAttribute('width', windowx / 2);
    canvas.setAttribute('height', windowy / 2);
    ctx = canvas.getContext("2d");
    drawObjects = [];
    keyState = {};
    quadTree = new Quadtree(quadTreeBounds);

    //make the friendly square
    player = new Rectangle(20, 20, 40, 40, 0, 0, XPhysicsBehaviorNormal, YPhysicsBehaviorNormal, XBoundaryBehaviorInCanvas, YBoundaryBehaviorInCanvas, playerObjectType, '#580000', null);
    drawObjects.push(new Rectangle(40, 100, canvas.width + (distanceOutsideCanvasBeforeDie / 2), canvas.clientHeight - 100, defaultEnemyRectangleVelocity, 0, null, YPhysicsBehaviorNormal, null, YBoundaryBehaviorInCanvas, enemyObjectType, null, OutOfCanvasDieBehavior));


    //define main loop
    mainloop = function() {

    //define the windowanimationframeobject
    animFrame = window.requestAnimationFrame ||
        window.webkitRequestAnimationFrame ||
        window.mozRequestAnimationFrame ||
        window.oRequestAnimationFrame ||
        window.msRequestAnimationFrame ||

    if (animFrame !== null) {
        var recursiveAnim = function() {
            animFrame(recursiveAnim, canvas);

        // start the mainloop
        animFrame(recursiveAnim, canvas);
    } else {
        // fallback to setInterval if the browser doesn't support requestAnimationFrame
        ONE_FRAME_TIME = 1000.0 / 60.0;
        gameLoop = setInterval(mainloop, ONE_FRAME_TIME);

$(function() {
    //get window width and height;
    windowx = window.innerWidth;
    windowy = window.innerHeight;


    $(document).on('change', '#sound-enabled-toggle', function() {
        var isChecked = $(this).is(':checked');
        if (isChecked) {
            playerJumpAudio = playerJumpMusicAudioSetup();
            playerBlinkAudio = playerBlinkMusicAudioSetup();
        } else {
            playerJumpAudio = new Audio('');
            playerBlinkAudio = new Audio('');

//left the function here in case I need to do anything else but for now it's  just clearing.
function buildQuadTree() {

function updateGame() {

    //determine if there are any keys pushed at the current point

    //loop for calculating and updating all objects positions/values.
    for (var i = 0; i < drawObjects.length; i++) {
        var object = drawObjects[i];
        quadTree.insert(new SimpleRectangle(object.x, object.y, object.width || (object.radius * 2), object.height || (object.radius * 2), object.name));

        //roundFloatingPoints Numbers to 2 decimal places

function drawGame() {
    //clear the canvas
    ctx.clearRect(0, 0, canvas.width, canvas.height);
    ctx.font = "20px Verdana";
    ctx.fillText("100,000", (canvas.width * .8), (canvas.clientHeight * .1));
    ctx.font = "15px Verdana";
    ctx.fillText("Temp Score", (canvas.width * .8), (canvas.clientHeight * .05));

    //draw all objects in drawObjects
    for (var i = 0; i < drawObjects.length; i++) {
        var object = drawObjects[i];
Html5 canvas game, creating a map much bigger than viewing canvas

Html5 canvas game, creating a map much bigger than viewing canvas

By : Jenna Olovic
Date : March 29 2020, 07:55 AM
will be helpful for those in need I'll give it a shot anyways. So, for the theoretical part:
What you are trying to achieve is simple Scene Management. A Scene needs a Camera, an object that stores the X and Y offset and the Width and Height it is going to display (The Width and Height is also known as the Projection Plane in 3D graphics). In every frame you will draw your Scene (or World) by the offset of your Camera.
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