Function polar

pattern/canvas.js:3350–3373

(img, x0, y0, callback)

// Based on: L. Spagnolini, 2007, http://dem.ocracy.org/libero/photobooth/

function polar(img, x0, y0, callback) {
    /* Returns a new Image based on a polar coordinates filter.
     * The given callback is a function(distance, angle) that returns new [distance, angle].
     */
    x0 = img.width / 2 + (x0 || 0);
    y0 = img.height / 2 + (y0 || 0);
    var p1 = new Pixels(img);
    var p2 = new Pixels(img);
    for (var y1=0; y1 < p1.height; y1++) {
        for (var x1=0; x1 < p1.width; x1++) {
            var x = x1 - x0;
            var y = y1 - y0;
            var d = Math.sqrt(Math.pow(x, 2) + Math.pow(y, 2));
            var a = Math.atan2(y, x);
            var v = callback(d, a); d=v[0]; a=v[1];
            p2.set(x1 + y1 * p1.width, p1.get(
                Math.round(x0 + Math.cos(a) * d) +
                Math.round(y0 + Math.sin(a) * d) * p1.width
            ));
        }
    }
    p2.update();
    return p2.image();
}

function bump(img, dx, dy, radius, zoom) {
    /* Returns the image with a dent distortion applied to it.