function draw()

in sketch.p5.js [78:162]
48 lines of code
7 McCabe index (conditional complexity)

function draw() {
    if (loadingResources) return;

    //console.log('draw');

    showLoaderAt(0, 'Rendering');

    BLEND_TO_P5 = {
        N: 'NORMAL',
        B: 'BLEND',
        A: 'ADD',
        K: 'DARKEST',
        L: 'LIGHTEST',
        D: 'DIFFERENCE',
        X: 'EXCLUSION',
        M: 'MULTIPLY',
        S: 'SCREEN',
        R: 'REPLACE',
        O: 'OVERLAY',
        H: 'HARD_LIGHT',
        F: 'SOFT_LIGHT',
        G: 'DODGE',
        U: 'BURN'
    };

    var p5 = this;

    // ==========
    // faster version, just ensures loading bar is shown, usually it stays at 0% until the end,
    // since GPU is busy with drawing layers

    // setTimeout(function() {
    //     clear();

    //     var layers = sketchConfig.layers;
    //     for (var i = 0; i < layers.length; i++) {
    //         if (layers[i] && layers[i] != 'dark') {
    //             showLoaderAt((i + 1) / layers.length, 'Rendering');
    //             console.time(layers[i].name || 'layer-' + i);
    //             layers[i].func(p5, layers[i].conf, ctx);
    //             console.timeEnd(layers[i].name || 'layer-' + i);
    //         }
    //         if (i == (layers.length - 1)) hideLoader();
    //     }

    //     hideLoader();
    // }, 10);

    // ==========
    // a tiny bit slower version, ensures to show loading bar for every step by waiting 10msec
    // between calls to free up GPU

    var layersToRender = sketchConfig.layers.values;
    var bgcolor = sketchConfig.layers.background || sketchConfig.bgcolor;

    var drawLayer = Kefir.emitter();

    var p5 = this;
    clear();

    background(color(bgcolor.r, bgcolor.g, bgcolor.b));

    drawLayer.delay(10).onValue(function(v) {
        showLoaderAt((v.index + 1) / layersToRender.length, 'Rendering');
        var layer = v.layer;
        //console.time(layer.name || 'layer-' + v.index);
        applyRenderOptions(p5, v.renderOptions, v.index);
        layer.func(p5, layer.conf, ctx, v.renderOptions);
        resetRenderOptions(p5);
        //console.timeEnd(layer.name || 'layer-' + v.index);
        if (v.index == (layersToRender.length - 1)) {
            hideLoader();
        }
    });

    for (var i = 0; i < layersToRender.length; i++) {
        drawLayer.emit({
            index: i,
            layer: layersToRender[i][0],
            renderOptions: layersToRender[i][1]
        });
    }

    // hideLoader();
}