spiral.pde by dave whyte https://dribbble.com/beesandbombs

spiral.pde

// by dave whyte https://dribbble.com/beesandbombs
int[][] result;
float t;

void setup() {
    setup_();
    result = new int[width * height][3];
}

void draw() {

    if (!recording) {
        t = mouseX * 1.0 / width;
        draw_();
    } else {
        for (int i = 0; i < width * height; i++)
            for (int a = 0; a < 3; a++)
                result[i][a] = 0;

        for (int sa = 0; sa < samplesPerFrame; sa++) {
            t = map(frameCount - 1 + sa * shutterAngle / samplesPerFrame, 0, numFrames, 0, 1);
            draw_();
            loadPixels();
            for (int i = 0; i < pixels.length; i++) {
                result[i][0] += pixels[i] >> 16 & 0xff;
                result[i][1] += pixels[i] >> 8 & 0xff;
                result[i][2] += pixels[i] & 0xff;
            }
        }

        loadPixels();
        for (int i = 0; i < pixels.length; i++)
            pixels[i] = 0xff << 24 | (result[i][0] / samplesPerFrame) << 16 |
            (result[i][1] / samplesPerFrame) << 8 | (result[i][2] / samplesPerFrame);
        updatePixels();


        loadPixels();
        for (int i = 0; i < pixels.length; i++)
            pixels[i] = lerpColor(color(245, 244, 215), color(149, 31, 43), red(pixels[i]) / 255.0);
        updatePixels();

        saveFrame("f###.gif");
        if (frameCount == numFrames)
            exit();

    }
}

//////////////////////////////////////////////////////////////////////////////

int samplesPerFrame = 4;
int numFrames = 72;
float shutterAngle = .8;

boolean recording = true;

int N = 12;
float d, y;
float maskD = 460;

PImage mask;

void setup_() {
    size(800, 600);
    smooth(8);
    background(0);
    fill(255);
    noStroke();
    ellipse(width / 2, height / 2, maskD, maskD);
    mask = get();

    strokeWeight(9);
    fill(0);
    stroke(255);
    strokeWeight(12);
}

void draw_() {
    background(0);
    pushMatrix();
    translate(width / 2, height / 2);
    for (int i = -2 * N; i < 5 * N; i++) {
        y = 280 * (t + i / float(N));
        pushMatrix();
        rotate(-TWO_PI * i / N);
        d = lerp(150, 500, i / float(N) + t);
        ellipse(0, y, d, d);
        popMatrix();
    }
    popMatrix();

    blend(mask, 0, 0, width, height, 0, 0, width, height, MULTIPLY);
    blend(mask, 0, 0, width, height, 0, 0, width, height, MULTIPLY); // seemingly need to do this twice, not sure why.
    pushStyle();
    noFill();
    ellipse(width / 2, height / 2, maskD, maskD);
    popStyle();
}