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gameengine.js
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gameengine.js
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/**
* Duy Huynh
* TCSS 491, Winter '16
* Assignment 2 - Interaction
* gameengine.js
*
*/
var boids = []; // Making this a 'global variable' for saving
var gameEngine; // Need to make this a global to access it elsewhere, like in calling save/load Socket.io
var SURFACE_WIDTH = 800;
var SURFACE_HEIGHT = 600;
// Defaulting to browser specific calls to animation frame to future proof:
window.requestAnimFrame = (function () {
return window.requestAnimationFrame ||
window.webkitRequestAnimationFrame ||
window.mozRequestAnimationFrame ||
window.oRequestAnimationFrame ||
window.msRequestAnimationFrame ||
function (/* function */ callback, /* DOMElement */ element) {
window.setTimeout(callback, 1000 / 60);
};
})(); // What does it mean to have parenthesis at the end again? It is being called right away?
// Game Engine has entities
function GameEngine() {
gameEngine = this;
this.entities = [];
this.enableDebug = false; // debugging flag for drawing bounding boxes
this.pauseKey = false;
this.ctx = null;
this.click = null;
this.mouse = null;
this.wheel = null;
this.surfaceWidth = null;
this.surfaceHeight = null;
}
/**
* On creation of GameEngine, create new game Timer, get width & height from canvas, begin recording inputs
* @param ctx
*/
GameEngine.prototype.init = function (ctx) {
this.ctx = ctx;
this.surfaceWidth = this.ctx.canvas.width;
this.surfaceHeight = this.ctx.canvas.height;
this.startInput(); // Allow input controls
this.timer = new Timer(); // Create game Timer
console.log('game initialized');
};
/**
* Begin game.
*/
GameEngine.prototype.start = function () {
console.log("starting game");
var that = this;
// Create some boids to start out with
// TODO: Init some boids, for loop, create, random locations
(function gameLoop() {
that.loop();
requestAnimFrame(gameLoop, that.ctx.canvas);
})();
};
/**
* Begin listening for inputs.
*/
GameEngine.prototype.startInput = function () {
console.log('Starting input');
var that = this;
/* === KEYBOARD EVENTS === */
this.ctx.canvas.addEventListener("keydown", function (e) {
// Prevent some keyboard navigation defaults:
// http://stackoverflow.com/questions/8916620/disable-arrow-key-scrolling-in-users-browser
if ([32, 37, 38, 39, 40].indexOf(e.keyCode) > -1) e.preventDefault(); // Spacebar, ←,↑,→,↓
// Debug: Enabling drawing of bounding boxes
if (e.which === 192) {
that.enableDebug ^= true; // '~' key to toggle debug
console.log("debugging turned " (that.enableDebug ? "on" : "off"));
}
// Pauses the game engine's loop()
if (e.which === 27) {
that.pauseKey ^= true;
console.log("Game Engine loop " (that.pauseKey ? "paused" : "unpaused"));
}
}, false);
/* === MOUSE SETTINGS === */
var getXandY = function (e) {
var x = e.clientX - that.ctx.canvas.getBoundingClientRect().left;
var y = e.clientY - that.ctx.canvas.getBoundingClientRect().top;
return {x: x, y: y};
};
this.ctx.canvas.addEventListener("mousemove", function (e) {
//console.log(getXandY(e));
that.mouse = getXandY(e);
}, false);
this.ctx.canvas.addEventListener("click", function (e) {
//console.log(getXandY(e));
that.click = getXandY(e);
var boid = new Boid(that, that.click.x Math.floor(Math.random() * 100) - 50, that.click.y Math.floor(Math.random() * 100) - 50, 10);
that.addEntity(boid);
boids.push(boid);
}, false);
this.ctx.canvas.addEventListener("wheel", function (e) {
//console.log(getXandY(e));
that.wheel = e;
//console.log(e.wheelDelta);
e.preventDefault();
}, false);
this.ctx.canvas.addEventListener("contextmenu", function (e) {
//console.log(getXandY(e));
that.rightclick = getXandY(e);
e.preventDefault();
}, false);
console.log('Input started');
};
/**
* Push an entity to the GameEngine's array of entities
* @param entity
*/
GameEngine.prototype.addEntity = function (entity) {
console.log('added ' entity);
this.entities.push(entity);
};
/**
* Draw entities onto canvas
*/
GameEngine.prototype.draw = function () {
// 1. Clear the window (Removes previously drawn things from canvas)
this.ctx.clearRect(0, 0, this.ctx.canvas.width, this.ctx.canvas.height);
// 2. Save old state
this.ctx.save();
// 3. Draw all entities from current scene onto canvas
//this.sceneManager.draw(this.ctx);
for (var i = 0, len = this.entities.length; i < len; i ) {
this.entities[i].draw(this.ctx);
}
// 4. Restore old state
this.ctx.restore();
};
/**
* Update each entity, removing those flagged for removal.
*/
GameEngine.prototype.update = function () {
// Cycle through the list of entities in GameEngine.
var entitiesCount = this.entities.length;
for (var i = 0; i < entitiesCount; i ) {
var entity = this.entities[i];
// Only update those not flagged for removal, for optimization
if (!entity.removeFromWorld) {
entity.update();
}
}
// Removal of flagged entities
for (var i = this.entities.length - 1; i >= 0; --i) {
if (this.entities[i].removeFromWorld) {
this.entities.splice(i, 1);
}
}
};
/**
* Basic loop for game.
* 1. Advance a game 'tick' on the game Timer.
* 2. Update Game Engine (entities)
* 3. Draw out to canvas
* 4. Clear spacebar to prevent repeated firing
*/
GameEngine.prototype.loop = function () {
if (!this.pauseKey) {
// 1. Advance game a 'tick' on the game timer
this.clockTick = this.timer.tick();
// 2. Update game engine (cycle through all entities)
this.update();
// 3. Redraw out to canvas
this.draw();
// 4. Reset inputs to prevent repeated firing
this.click = null;
this.rightclick = null;
this.wheel = null;
this.space = null;
}
if (this.pauseKey) {
drawTextWithOutline(this.ctx, "80pt Impact", "-PAUSED-", this.surfaceWidth / 4, this.surfaceHeight / 2, 'purple', 'white');
}
};
function Timer() {
this.gameTime = 0;
this.maxStep = 0.05;
this.wallLastTimestamp = 0;
}
Timer.prototype.tick = function () {
var wallCurrent = Date.now(); // Retrieve current time
var wallDelta = (wallCurrent - this.wallLastTimestamp) / 1000;
this.wallLastTimestamp = wallCurrent;
var gameDelta = Math.min(wallDelta, this.maxStep);
this.gameTime = gameDelta;
//console.log(this.gameTime);
return gameDelta;
};