Scene-Starlight/Starlight-Renderer.js

"use strict";

import random from './Random'; // Bounded random number generation
import Vector from './Vector'; // 2D vector class
// Subclasses
import Star from './Star';

// ~~~

class StarlightRenderer
{
	constructor(canvas)
	{
		// The colour of the sky in the background.
		this.skyColour = "hsla(248, 100%, 23%, 1)";
		
		// ~~~
		
		this.canvas = canvas;
		this.context = canvas.getContext("2d");
		this.trackWindowSize();
		
		this.lastFrame = new Date();
		
		// ~~~
		
		this.stars = [];
		for(let i = 0; i < 100; i++)
		{
			this.stars.push(new Star(
				this.canvas,
				new Vector(
					random(0, this.canvas.width),
					random(0, this.canvas.height)
				),
				random(0, 10)
			));
		}
	}
	
	nextFrame()
	{
		this.update();
		this.render(this.canvas, this.context);
		requestAnimationFrame(this.nextFrame.bind(this));
	}
	
	update()
	{
		// Calculate the time between this frame and the last one
		this.currentFrame = new Date();
		this.currentDt = this.currentFrame - this.lastFrame;
		
		
		// Stars
		for(let star of this.stars)
			star.update(this.currentDt);
	}
	
	render(canvas, context)
	{
		// Background
		context.fillStyle = this.skyColour;
		context.fillRect(0, 0, this.canvas.width, this.canvas.height);
		
		// Stars
		for(let star of this.stars)
			star.render(context);
	}
	
	/**
	 * Updates the canvas size to match the current viewport size.
	 */
	matchWindowSize() {
		this.canvas.width = window.innerWidth;
		this.canvas.height = window.innerHeight;
		
		//this.render(this.context);
	}
	
	/**
	 * Makes the canvas size track the window size.
	 */
	trackWindowSize() {
		this.matchWindowSize();
		window.addEventListener("resize", this.matchWindowSize.bind(this));
	}
}

window.addEventListener("load", function (event) {
	var canvas = document.getElementById("canvas-main"),
		renderer = new StarlightRenderer(canvas);
	renderer.nextFrame();
	window.renderer = renderer;
});