lee chu – project 07 – curves

lrchu

// lee chu
// section c
// lrchu@andrew.cmu.edu
// project - 07

// variables for equation
var angle;
var t;
var x;
var y;
var xx;
var yy;

// characteristics of shapes
var sizes = [];
var size;
var ct;
var step;

// color
var r;
var g;
var b;

function setup() {
    createCanvas(480, 300);
    noFill();
    strokeWeight(0);
    angle = 0;
    t = 20;

    // create sizing for layers
    for (h = 0; h < 60; h ++) {
        sizes.push(h * 3);
    }
    size = 20;
    ct = 200;

    // color control
    r = 36;
    g = 33;
    b = 40;
    step = 5;
}

function draw() {
    background(r, g, b);

    // change turn direction and rate
    if (mouseX < width / 2 & mouseX > 0 && mouseY < height && mouseY > 0) {
        angle -= (width / 2 - constrain(mouseX, 0, width / 2)) / width / 2 / 6;
    }
    if (mouseX > width / 2 & mouseX < width && mouseY < height && mouseY > 0) {
        angle += (constrain(mouseX, width/2, width) - width / 2) / width / 2 / 6;
    }

    // generate shapes
    for (j = 0; j < sizes.length; j ++) {
        cata(sizes[sizes.length - j]);
        r = (r + step * (j + 1)) % 255;
        g = (g + step * (j + 1)) % 255;
        b = (b + step * (j + 1)) % 255;
    }
    deltoid(sizes[1]);
}

function cata(size) {
    fill(r, g, b);
    push();
    translate(width / 2, height / 2);
    beginShape();
    for (i = 0; i < ct; i ++) {
        t = map(i, 0, ct, 0, 2 * PI);
        xx = 3 * cos(t) + cos(3 * t + 2 * angle) - cos(2 * angle);
        yy = - 3 * sin(t) + sin(3 * t + 2 * angle) - sin(2 * angle);
        vertex(xx * size, yy * size);
    }
    endShape();
    pop();
}

function deltoid(sizeD) {
    fill('black');
    push();
    translate(width / 2, height / 2);
    beginShape();
    for (i = 0; i < ct; i ++) {
        t = map(i, 0, ct, 0, 2 * PI);
        x = 2 * cos(t) + cos(2 * t);
        y = -2 * sin(t) + sin(2 * t);
        vertex(x * sizeD, y * sizeD);
    }
    endShape();
    pop();
}

I was intrigued by the deltoid catacaustic, which consists of the deltoid, a triangle bowing in, and the catacaustic which circumscribes the deltoid as it rotates around its axis. The center of all the layers of the catacaustic is the black deltoid in the middle of the canvas.