util.js

// returns a random integer between 0 and n-1
function randomInt(n) {
    return Math.floor(Math.random() * n);
};

// returns a string that can be used as a rgb web color
function rgb(r, g, b) {
    return "rgb(" + r + "," + g + "," + b + ")";
};

// returns a string that can be used as a hsl web color
function hsl(h, s, l) {
    return "hsl(" + h + "," + s + "%," + l + "%)";
};

function distance(A, B) {
    return Math.sqrt((B.x - A.x) * (B.x - A.x) + (B.y - A.y)*(B.y - A.y));
};

function collide(A, B) {
    return (distance(A, B) < A.radius + B.radius);
};

function canSee(A, B) { // if A can see B
    return (distance(A, B) < A.visualRadius + B.radius);
};

function getFacing(velocity) {
    if (velocity.x === 0 && velocity.y === 0) return 4;
    let angle = Math.atan2(velocity.y, velocity.x) / Math.PI;

    if (-0.625 < angle && angle < -0.375) return 0;
    if (-0.375 < angle && angle < -0.125) return 1;
    if (-0.125 < angle && angle < 0.125) return 2;
    if (0.125 < angle && angle < 0.375) return 3;
    if (0.375 < angle && angle < 0.625) return 4;
    if (0.625 < angle && angle < 0.875) return 5;
    if (-0.875 > angle || angle > 0.875) return 6;
    if (-0.875 < angle && angle < -0.625) return 7;
};

var currentChat;
function loadChat(chat) {
    if (!chat) chat = {
        message: "", resp1: { text: "" }, resp2: { text: "" }, resp3: { text: "" } };

    currentChat = chat;

    var chatBox = document.getElementById("message");
    chatBox.innerHTML = chat.message;

    var resp = document.getElementById("response1");
    resp.innerHTML = chat.resp1.text;
    resp = document.getElementById("response2");
    resp.innerHTML = chat.resp2.text;
    resp = document.getElementById("response3");
    resp.innerHTML = chat.resp3.text;
};

// creates an alias for requestAnimationFrame for backwards compatibility
window.requestAnimFrame = (function () {
    return window.requestAnimationFrame ||
        window.webkitRequestAnimationFrame ||
        window.mozRequestAnimationFrame ||
        window.oRequestAnimationFrame ||
        window.msRequestAnimationFrame ||
        function (/* function */ callback, /* DOMElement */ element) {
            window.setTimeout(callback, 1000 / 60);
        };
})();

// add global parameters here

var PARAMS = {
    DEBUG: true
};