class Vector {
constructor(public x: number, public y: number, public z: number) { }
static times(k: number, v: Vector) {
return new Vector(k * v.x, k * v.y, k * v.z);
}
static minus(v1: Vector, v2: Vector) {
return new Vector(v1.x - v2.x, v1.y - v2.y, v1.z - v2.z);
}
static plus(v1: Vector, v2: Vector) {
return new Vector(v1.x + v2.x, v1.y + v2.y, v1.z + v2.z);
}
static dot(v1: Vector, v2: Vector) {
return v1.x * v2.x + v1.y * v2.y + v1.z * v2.z;
}
static mag(v: Vector) {
return Math.sqrt(v.x * v.x + v.y * v.y + v.z * v.z);
}
static norm(v: Vector) {
var mag = Vector.mag(v);
var div = (mag === 0) ? Infinity : 1.0 / mag;
return Vector.times(div, v);
}
static cross(v1: Vector, v2: Vector) {
return new Vector(v1.y * v2.z - v1.z * v2.y,
v1.z * v2.x - v1.x * v2.z,
v1.x * v2.y - v1.y * v2.x);
}
}
class Color {
constructor(public r: number, public g: number, public b: number) { }
static scale(k: number, v: Color) {
return new Color(k * v.r, k * v.g, k * v.b);
}
static plus(v1: Color, v2: Color) {
return new Color(v1.r + v2.r, v1.g + v2.g, v1.b + v2.b);
}
static times(v1: Color, v2: Color) {
return new Color(v1.r * v2.r, v1.g * v2.g, v1.b * v2.b);
}
static white = new Color(1.0, 1.0, 1.0);
static grey = new Color(0.5, 0.5, 0.5);
static black = new Color(0.0, 0.0, 0.0);
static background = Color.black;
static defaultColor = Color.black;
static toDrawingColor(c: Color) {
var legalize = d => d > 1 ? 1 : d;
return {
r: Math.floor(legalize(c.r) * 255),
g: Math.floor(legalize(c.g) * 255),
b: Math.floor(legalize(c.b) * 255)
}
}
}
class Camera {
forward: Vector;
right: Vector;
up: Vector;
constructor(public pos: Vector, lookAt: Vector) {
var down = new Vector(0.0, -1.0, 0.0);
this.forward = Vector.norm(Vector.minus(lookAt, this.pos));
this.right = Vector.times(1.5, Vector.norm(Vector.cross(this.forward, down)));
this.up = Vector.times(1.5, Vector.norm(Vector.cross(this.forward, this.right)));
}
}
interface Ray {
start: Vector;
dir: Vector;
}
interface Intersection {
thing: Thing;
ray: Ray;
dist: number;
}
interface Surface {
diffuse: (pos: Vector) => Color;
specular: (pos: Vector) => Color;
reflect: (pos: Vector) => number;
roughness: number;
}
interface Thing {
intersect: (ray: Ray) => Intersection;
normal: (pos: Vector) => Vector;
surface: Surface;
}
interface Light {
pos: Vector;
color: Color;
}
interface Scene {
things: Thing[];
lights: Light[];
camera: Camera;
}
class Sphere implements Thing {
radius2: number;
constructor(public center: Vector, radius: number, public surface: Surface) {
this.radius2 = radius * radius;
}
normal(pos: Vector): Vector {
return Vector.norm(Vector.minus(pos, this.center));
}
intersect(ray: Ray) {
var eo = Vector.minus(this.center, ray.start);
var v = Vector.dot(eo, ray.dir);
var dist = 0;
if (v >= 0) {
var disc = this.radius2 - (Vector.dot(eo, eo) - v * v);
if (disc >= 0) {
dist = v - Math.sqrt(disc);
}
}
if (dist === 0) {
return null;
} else {
return { thing: this, ray: ray, dist: dist };
}
}
}
class Plane implements Thing {
normal: (pos: Vector) => Vector;
intersect: (ray: Ray) => Intersection;
constructor(norm: Vector, offset: number, public surface: Surface) {
this.normal = function(pos: Vector) { return norm; }
this.intersect = function(ray: Ray): Intersection {
var denom = Vector.dot(norm, ray.dir);
if (denom > 0) {
return null;
} else {
var dist = (Vector.dot(norm, ray.start) + offset) / (-denom);
return { thing: this, ray: ray, dist: dist };
}
}
}
}
module Surfaces {
export var shiny: Surface = {
diffuse: function(pos) { return Color.white; },
specular: function(pos) { return Color.grey; },
reflect: function(pos) { return 0.7; },
roughness: 250
}
export var checkerboard: Surface = {
diffuse: function(pos) {
if ((Math.floor(pos.z) + Math.floor(pos.x)) % 2 !== 0) {
return Color.white;
} else {
return Color.black;
}
},
specular: function(pos) { return Color.white; },
reflect: function(pos) {
if ((Math.floor(pos.z) + Math.floor(pos.x)) % 2 !== 0) {
return 0.1;
} else {
return 0.7;
}
},
roughness: 150
}
}
class RayTracer {
private maxDepth = 5;
private intersections(ray: Ray, scene: Scene) {
var closest = +Infinity;
var closestInter: Intersection = undefined;
for (var i in scene.things) {
var inter = scene.things[i].intersect(ray);
if (inter != null && inter.dist < closest) {
closestInter = inter;
closest = inter.dist;
}
}
return closestInter;
}
private testRay(ray: Ray, scene: Scene) {
var isect = this.intersections(ray, scene);
if (isect != null) {
return isect.dist;
} else {
return undefined;
}
}
private traceRay(ray: Ray, scene: Scene, depth: number): Color {
var isect = this.intersections(ray, scene);
if (isect === undefined) {
return Color.background;
} else {
return this.shade(isect, scene, depth);
}
}
private shade(isect: Intersection, scene: Scene, depth: number) {
var d = isect.ray.dir;
var pos = Vector.plus(Vector.times(isect.dist, d), isect.ray.start);
var normal = isect.thing.normal(pos);
var reflectDir = Vector.minus(d, Vector.times(2, Vector.times(Vector.dot(normal, d), normal)));
var naturalColor = Color.plus(Color.background,
this.getNaturalColor(isect.thing, pos, normal, reflectDir, scene));
var reflectedColor = (depth >= this.maxDepth) ? Color.grey : this.getReflectionColor(isect.thing, pos, normal, reflectDir, scene, depth);
return Color.plus(naturalColor, reflectedColor);
}
private getReflectionColor(thing: Thing, pos: Vector, normal: Vector, rd: Vector, scene: Scene, depth: number) {
return Color.scale(thing.surface.reflect(pos), this.traceRay({ start: pos, dir: rd }, scene, depth + 1));
}
private getNaturalColor(thing: Thing, pos: Vector, norm: Vector, rd: Vector, scene: Scene) {
var addLight = (col, light) => {
var ldis = Vector.minus(light.pos, pos);
var livec = Vector.norm(ldis);
var neatIsect = this.testRay({ start: pos, dir: livec }, scene);
var isInShadow = (neatIsect === undefined) ? false : (neatIsect <= Vector.mag(ldis));
if (isInShadow) {
return col;
} else {
var illum = Vector.dot(livec, norm);
var lcolor = (illum > 0) ? Color.scale(illum, light.color)
: Color.defaultColor;
var specular = Vector.dot(livec, Vector.norm(rd));
var scolor = (specular > 0) ? Color.scale(Math.pow(specular, thing.surface.roughness), light.color)
: Color.defaultColor;
return Color.plus(col, Color.plus(Color.times(thing.surface.diffuse(pos), lcolor),
Color.times(thing.surface.specular(pos), scolor)));
}
}
return scene.lights.reduce(addLight, Color.defaultColor);
}
render(scene, ctx, screenWidth, screenHeight) {
var getPoint = (x, y, camera) => {
var recenterX = x => (x - (screenWidth / 2.0)) / 2.0 / screenWidth;
var recenterY = y => -(y - (screenHeight / 2.0)) / 2.0 / screenHeight;
return Vector.norm(Vector.plus(camera.forward, Vector.plus(Vector.times(recenterX(x), camera.right), Vector.times(recenterY(y), camera.up))));
}
for (var y = 0; y < screenHeight; y++) {
for (var x = 0; x < screenWidth; x++) {
var color = this.traceRay({ start: scene.camera.pos, dir: getPoint(x, y, scene.camera) }, scene, 0);
var c = Color.toDrawingColor(color);
ctx.fillStyle = "rgb(" + String(c.r) + ", " + String(c.g) + ", " + String(c.b) + ")";
ctx.fillRect(x, y, x + 1, y + 1);
}
}
}
}
function defaultScene(): Scene {
return {
things: [new Plane(new Vector(0.0, 1.0, 0.0), 0.0, Surfaces.checkerboard),
new Sphere(new Vector(0.0, 1.0, -0.25), 1.0, Surfaces.shiny),
new Sphere(new Vector(-1.0, 0.5, 1.5), 0.5, Surfaces.shiny)],
lights: [{ pos: new Vector(-2.0, 2.5, 0.0), color: new Color(0.49, 0.07, 0.07) },
{ pos: new Vector(1.5, 2.5, 1.5), color: new Color(0.07, 0.07, 0.49) },
{ pos: new Vector(1.5, 2.5, -1.5), color: new Color(0.07, 0.49, 0.071) },
{ pos: new Vector(0.0, 3.5, 0.0), color: new Color(0.21, 0.21, 0.35) }],
camera: new Camera(new Vector(3.0, 2.0, 4.0), new Vector(-1.0, 0.5, 0.0))
};
}
function exec() {
var canv = document.createElement("canvas");
canv.width = 256;
canv.height = 256;
document.body.appendChild(canv);
var ctx = canv.getContext("2d");
var rayTracer = new RayTracer();
return rayTracer.render(defaultScene(), ctx, 256, 256);
}
exec();
