JSFiddle - React, Tailwind, and code Playground

by bornander

HTML

<!DOCTYPE html>
<html>
    
    <body>
        <canvas id="myCanvas" width="800" height="600"></canvas>
        <script>
            function fltEquals(lhs, rhs) {
                return Math.abs(lhs - rhs) < 0.00001;
            }

            function fltRound4(num) {
                return Math.round(num * 10000.0) / 10000.0;
            }

            var TWO_PI = Math.PI * 2;
            var HALF_PI = Math.PI / 2;

            function Vector2D(x, y) {
                this.x = x;
                this.y = y;
            }

            Vector2D.prototype.str = function() {
                return "(" + this.x + ", " + this.y + ")";
            };

            Vector2D.prototype.clear = function() {
                this.x = 0;
                this.y = 0;
            };

            Vector2D.prototype.length = function() {
                return Math.sqrt(this.x * this.x + this.y * this.y);
            };

            Vector2D.prototype.equals = function(other) {
                return fltEquals(this.x, other.x) && fltEquals(this.y, other.y);
            };

            Vector2D.normalize = function(v) {
                var l = v.length();
                return new Vector2D(v.x / l, v.y / l);
            };

            Vector2D.add = function(lhs, rhs) {
                return new Vector2D(lhs.x + rhs.x, lhs.y + rhs.y);
            };

            Vector2D.sub = function(lhs, rhs) {
                return new Vector2D(lhs.x - rhs.x, lhs.y - rhs.y);
            };

            Vector2D.mul = function(lhs, factor) {
                return new Vector2D(lhs.x * factor, lhs.y * factor);
            };

            Vector2D.dot = function(lhs, rhs) {
                return lhs.x * rhs.x + lhs.y * rhs.y;
            };

            /* not an actual cross-product */
            Vector2D.cross = function(vector) {
                return new Vector2D(vector.y, -vector.x);
            };

            Vector2D.distanceBetween = function(lhs, rhs) {
                var...