# Jinhee Lee; Project 07

``````//Jinhee Lee
//Section C
//jinheel1@andrew.cmu.edu
//Project-07

var nPoints = 100;
var angle = 0; //start angle for rotating (out of canvas)

function setup() {
createCanvas(500, 500);
}

function draw() {
background(250);

translate(width / 2, height / 2);
if (mouseX > width) { //this one's for you, Anirudh
rotate(angle); //shape rotates in place
}

drawDeltoidCurve(); //calling helper function

angle += 0.05; //increment for rotation
}

function drawDeltoidCurve() {
// Deltoid
// http://mathworld.wolfram.com/Deltoid.html

var x; //curve in parametric form
var y;

var minSize = 80; //min size of shape
var maxSize = 160; //max size of shape
var mapA = map(mouseY, 0, width, minSize, maxSize); //maps size between minSize and maxSize
var a = constrain(mapA, minSize, maxSize); //so that shape doesn't grow when mouseX beyond canvas
var b = a / 3; //variable for curve equations
var rot = constrain(mouseX / 30, 0, width / 30); //rotate according to mouseX

fill("red"); //larger red circle
ellipse(0, 0, 2 * a, 2 * a);

fill(0);
beginShape();
for (var i = 0; i < nPoints; i++) {
var theta = map(i, 0, nPoints, 0, TWO_PI);

x = 2 * b * cos(theta) + b * cos(2 * theta - rot); //parametric equations of curve
y = 2 * b * sin(theta) - b * sin(2 * theta - rot);
vertex(x, y);
}
endShape(CLOSE);

fill("red"); //smaller red circle
ellipse(0, 0, b, b);
}``````

Having to implement parametric equations felt daunting at first, but in a broader look, it was mostly plugging in the deltoid curve’s equation with the templates given in the prompt. The two red circles I made separately fairly easily, but I made them share variables with the deltoid curve that governed its size, so they would all grow proportionally.

P.S.,

Fun fact, if you spin the deltoid to the right past the canvas, then you get-
YOU ARE NOW UNDER MY GENJUTSU