gravitywell/bullet.js

function Bullet(game, ownerId) {
	this.position = {x: 0, y: 0};
	this.velocity = {x: 0, y: 0};
	this.acceleration = {x: 0, y: 0};
	this.angleRadians = 0;
	this.fireRate = 5;
	this.lifetime = 100;
	this.timeToDie = 0;
	this.isDead = false;
	this.owner = ownerId;
	this.damage = 1;

	this.fire = function(startPosition, startVelocity, directionRadians) {
		this.position.x = startPosition.x + 8 * Math.cos(directionRadians);
		this.position.y = startPosition.y + 8 * Math.sin(directionRadians);
		this.velocity.x = startVelocity.x;
		this.velocity.y = startVelocity.y;
		this.angleRadians = directionRadians;
		this.velocity.x += this.fireRate * Math.cos(directionRadians);
		this.velocity.y += this.fireRate * Math.sin(directionRadians);		
		this.timeToDie = this.lifetime;
	}

	this.update = function(delta) {
		this.timeToDie -= delta;
		if(this.timeToDie <= 0) {
			game.expireBullet(this);
			return;
		}

		//bullets affected by gravity
		/*this.acceleration.x = 0;
		this.acceleration.y = 0;

		var nearestSystem = game.getNearestSystem(game, this);
		nearestSystem.addGravity(this);

		for(var index in nearestSystem.planets) {
			var planet = nearestSystem.planets[index];
			planet.addGravity(this);
		}

		this.velocity.x += this.acceleration.x;
		this.velocity.y += this.acceleration.y; */
		
		this.position.x += this.velocity.x * delta;
		this.position.y += this.velocity.y * delta;
	}
	this.draw = function(context) {
		if(this.isDead) {
			return;
		}
		
		//bullet
		context.fillStyle = "#DDDDDD";
		context.beginPath();
		context.arc(this.position.x, this.position.y, 2, 0, 2 * Math.PI);
		context.fill();

		//missile
		/*
		context.strokeStyle = "#DDDDDD";
		context.beginPath();
		context.moveTo(truePos.x, truePos.y);
		context.lineTo(truePos.x + 15* Math.cos(this.angleRadians), truePos.y + 15*  Math.sin(this.angleRadians));
		context.stroke();
		*/
		
	}

	this.checkHit = function(ship) {
		var distance = Math.sqrt(Math.pow(ship.position.x - this.position.x, 2) + Math.pow(ship.position.y - this.position.y, 2));
		if(ship.id != ownerId && ship.width / 2 >= distance) {
			ship.takeDamage(this.damage, ownerId);
			this.isDead = true;
		}
	}
};