Month: October 2020

//Diana McLaughlin, dmclaugh@andrew.cmu.edu, Section A
//a code that experiments with epicycloids and hypotrochoids

var nPoints = 500;
var theta = 0;

function setup() {
    createCanvas(480, 480);

}

function draw() {
	var g = map(mouseX, 0, 480, 0, 160);
	var b = map(mouseX, 0, 480, 75, 255);
    background(0, g, b); //shades of blue

    for(var y = 0; y <= 480; y += 100) { //draw the vertical yellow epicycloids
    	push();
    	translate(0, y);
    	Epicycloid2();
    	pop();
    	push();
    	translate(480, y);
    	Epicycloid2();
    	pop();
    }

    for (var x = 20; x <= 480; x += 100) {
    	    push(); //top row, yellow epicycloids
    	    translate(x, 0);
    	    Epicycloid2(); 
    	    pop();
            push(); //second row, pink hypotrochoids
            translate(x, 120);
            Hypotrochoid1();
            pop();
            push(); // middle row, purple epicycloids
    	    translate(x, 240);
    	    Epicycloid1();
    	    pop();
            push(); //fourth row, green hypotrochoids
            translate(x, 360);
            Hypotrochoid2();
            pop();
            push(); //bottom row, yellow epicycloids
            translate(x, 480);
            Epicycloid2();
            pop();

    }

    
}

function Epicycloid1() { //purple epicycloid
    var a = map(mouseX, 0, 480, 0, 70); //inner radius
    var b = map(mouseY, 0, 480, 0, 20); //outter radius

    strokeWeight(1);
    stroke(255, 128, 255); //light purple
    noFill();
    beginShape();
    for (var i = 0; i < nPoints; i++) {
        var theta = map(i, 0, 125, 0, TWO_PI);
        x = (a+b) * cos(theta) - b * cos(((a+b)/b) * theta);
        y = (a+b) * sin(theta) - b * sin(((a+b)/b) * theta);
        vertex(x, y);
    }
    endShape();
}

function Epicycloid2() { //yellow, epicycloid, used for the border
    var a = map(mouseX, 0, 480, 0, 30); //inner radius
    var b = map(mouseY, 0, 480, 0, 20); //outter radius

    strokeWeight(0.75);
    stroke(255, 255, 0); //yellow
    noFill();
    beginShape();
    for (var i=0; i<nPoints; i++) {
        var theta = map(i, 0, 45, 0, TWO_PI);
        x = (a+b) * cos(theta) - b * cos(((a+b)/b) * theta);
        y = (a+b) * sin(theta) - b * sin(((a+b)/b) * theta);
        vertex(x, y);
    }
    endShape();
}


function Hypotrochoid1() { //pink hypotrochoid
    var a = map(mouseX, 0, 480, 0, 125); //outter radius
    var b = map(mouseY, 0, 480, 0, 50); //inner radius
    var h = map(mouseX, 0, 480, 0, 60); // tracing distance from center of inner circle

    strokeWeight(1);
    stroke(255, 128, 200); //pink
    noFill();
    beginShape();
    for (var i=0; i<nPoints; i++) {
        var theta = map(i, 0, 120, 0, TWO_PI);
        x = (a-b) * cos(theta) + h * cos(((a-b)/b) * theta);
        y = (a-b) * sin(theta) - h * sin(((a-b)/b) * theta);
        vertex(x, y);
    }
    endShape();
}

function Hypotrochoid2() { //green hypotrochoid
    var a = map(mouseX, 0, 480, 0, 100); //outter radius
    var b = map(mouseY, 0, 480, 0, 40); //inner radius
    var h = map(mouseY, 0, 480, 0, 60); //tracing distance from center of inner circle

    strokeWeight(1);
    stroke(0, 255, 0);
    noFill();
    beginShape();
    for (var i=0; i<nPoints; i++) {
        var theta = map(i, 0, 120, 0, TWO_PI);
        x = (a-b) * cos(theta) + h * cos(((a-b)/b) * theta);
        y = (a-b) * sin(theta) - h * sin(((a-b)/b) * theta);
        vertex(x, y);
    }
    endShape();
}