How can I make copies of the canvas? Original + copy next to it, with same contents.

I have the following code in setup():

originalCanvas = createCanvas(windowWidth/2, windowHeight);
originalCanvas.position(0, 0);

copiedCanvas = originalCanvas;
copiedCanvas.position(windowWidth/2, 0);

However, only the right half of the screen is black. The left part is white, which I find weird. If my approach didn't work, shouldn't at least the left part be black and the right part white?

When I put an ellipse with mouseX and mouseY in draw(), it only shows in the black/right canvas. The left canvas seems inactive.

I know about createGraphics, but then I would have to always draw things twice, right? For example "original.ellipse(...) and copy.ellipse(...)" - or am I missing something?


  • Draw whatever you want on the left half.

    Use get() to get an image of the left half.

    Use image() to redraw it on the right.

  • Okay, so I got it working the way I want, but Chrome runs out of memory after a few seconds. I'm a newbie to programming, so I don't know how to determine what's causing it.

    Also, why doesn't the tint affect the background? The mouse ellipses get coloured green, but the background is black.

    var copiedCanvas;
    function setup() {
        createCanvas(windowWidth, windowHeight);
        background(255, 0, 0);
    function draw() {
        ellipse(mouseX, mouseY, 10, 10)
    function copyCanvas() {
        copiedCanvas = get();
        tint(0, 255, 0);
        image(copiedCanvas, windowWidth/2, 0)
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