111 lines
2.6 KiB
JavaScript
111 lines
2.6 KiB
JavaScript
"use strict";
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import random from './Random'; // Bounded random number generation
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import Vector from './Vector'; // 2D vector class
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import Range from './Range'; // Range representation
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// Subclasses
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import Star from './Star';
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// ~~~
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class StarlightRenderer
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{
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constructor(canvas)
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{
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// The colour of the sky in the background.
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this.skyColour = "hsla(248, 100%, 23%, 1)";
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this.starSize = new Range(2, 10);
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// ~~~
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this.canvas = canvas;
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this.context = canvas.getContext("2d");
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this.trackWindowSize();
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this.lastFrame = +new Date() / 1000;
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// ~~~
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this.stars = [];
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for(let i = 0; i < 100; i++)
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{
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let nextStar = new Star(
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this.canvas,
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new Vector(
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random(0, this.canvas.width),
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random(0, this.canvas.height)
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),
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random(this.starSize.min, this.starSize.max)
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);
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nextStar.pointCount = random(4, 8);
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// Make larger stars tend towards having longer points
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nextStar.innerRingRatio = random(0.2, 0.8, true);
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nextStar.innerRingRatio = (nextStar.innerRingRatio + nextStar.innerRingRatio*(1 - (nextStar.size / this.starSize.max))) / 2;
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nextStar.rotation = random(0, Math.PI*2, true);
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nextStar.rotationStep = random(0.1, 1, true);
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if(random(0, 2) == 0)
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nextStar.rotationStep *= -1;
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nextStar.alpha = random(0.2, 0.9, true);
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this.stars.push(nextStar);
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}
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}
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nextFrame()
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{
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this.update();
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this.render(this.canvas, this.context);
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requestAnimationFrame(this.nextFrame.bind(this));
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}
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update()
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{
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// Calculate the time between this frame and the last one
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this.currentFrame = (+new Date()) / 1000;
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this.currentDt = this.currentFrame - this.lastFrame;
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// Update all the stars
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for(let star of this.stars)
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star.update(this.currentDt);
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this.lastFrame = this.currentFrame;
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}
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render(canvas, context)
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{
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// Background
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context.fillStyle = this.skyColour;
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context.fillRect(0, 0, this.canvas.width, this.canvas.height);
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// Stars
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for(let star of this.stars)
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star.render(context);
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}
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/**
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* Updates the canvas size to match the current viewport size.
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*/
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matchWindowSize() {
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this.canvas.width = window.innerWidth;
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this.canvas.height = window.innerHeight;
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//this.render(this.context);
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}
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/**
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* Makes the canvas size track the window size.
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*/
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trackWindowSize() {
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this.matchWindowSize();
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window.addEventListener("resize", this.matchWindowSize.bind(this));
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}
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}
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window.addEventListener("load", function (event) {
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var canvas = document.getElementById("canvas-main"),
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renderer = new StarlightRenderer(canvas);
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renderer.nextFrame();
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window.renderer = renderer;
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});
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