Project 07: Composition with Curves

var bgR;
var bgG;
var bgB;
var x;
var y;

function setup() {
    createCanvas(480, 480);
    frameRate(10);
}

function draw() {
    bgR = map(-mouseY, 0, height, 50, 100); //select random background colors
    bgG = map(-mouseX, 0, width, 50, 200);
    bgB = map(-mouseY, 0, height, 0, 100);
    background(bgR, bgG, bgB);
    translate(220, 220);
    for (var c = 1; c < 5; c ++){ //draw the curve
        for (var d = 1; d < 5; d ++){
            push();
            translate(c * 10, d * 10);
            drawEpicycloidPedalCurve(); //reference to link -- https://mathworld.wolfram.com/EpicycloidPedalCurve.html
            pop();
        }
    }
}

function drawEpicycloidPedalCurve() {
    var a = map(mouseX, 0, width, 15, 100); //parameter of the curve moves with the mouse
    var b = map(mouseY, 0, height, 15, 50);
    noFill();
    stroke(mouseX, mouseY, 180);
    strokeWeight(0.8);

    push();
    beginShape(); //draw the curve
    for (var i = 0; i <= 600; i ++) {
        var theta = map(i, 0, 100, 0, PI); 
        x = (a+b)*cos(theta) - b*cos(((a+b)*theta)/b); //epicycloids are given by the parametric equations
        y = (a+b)*sin(theta) - b*sin(((a+b)*theta)/b);
        vertex(x, y);
    }
    endShape();
    pop();
}