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raytracer.html
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raytracer.html
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<html>
<head>
<script src = 'http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js'></script>
<script src = './plib.js'></script>
<style type = 'text/css'>
body{background-color:#eee;font-family:'Gill sans', helvetica, arial, sans; text-align:center;}
p{width:40em; margin: 0 auto;}
</style>
</head>
<body>
<h1>Tracing Rays</h1>
<canvas id = "rays" width = "500" height = "250">
This only works in a modern browser that supports the <canvas> element. For example Firefox 3.5+, Safari or Chrome.
</canvas>
<br />
<button id = "start_raytracer">Start</button>
<br />
<p><em>The raytracer is pretty processor intensive - I recommend you run it in Google Chrome which has the fastest javascript engine I've found. Also tested in Firefox/Safari. Will certainly not work in IE.</em></p>
<script type = "text/javascript">
var rays = {};
/** Primitives **/
rays.Sphere = function(pos, radius, color, phong, reflection){
this.pos = pos;
this.radius = radius;
this.color = function(pt){return color};
this.phong = phong;
this.reflection = reflection || 0;
this.intersects = function(ro, rd){
var rdn = plib.v3.normalise(rd);
var dst =plib.v3.sub(ro, this.pos);
var b = plib.v3.dot(dst, rdn);
var c = plib.v3.dot(dst, dst)- this.radius*this.radius;
var d = b*b-c;
if (d){
return -b - Math.sqrt(d)}
return false;
}
this.normal = function(pt){
return plib.v3.normalise(plib.v3.sub(pt, this.pos));
}
};
rays.CheckerYPlane = function(y, col1, col2){
this.y = y;
this.col1 = col1;
this.col2 = col2;
this.phong = 0;
this.reflection = 0.1;
this.intersects = function(ro, rd){
var rdn = plib.v3.normalise(rd);
return plib.v3.dot([0,1,0], plib.v3.sub([0,this.y,0], ro))/ plib.v3.dot([0,1,0], rdn);
}
this.normal = function(pt){
return [0,1,0];
}
this.color = function(pt){
var zig = pt[0] > 0 ? parseInt(Math.abs(pt[0])/50) % 2 == 0 : parseInt(Math.abs(pt[0])/50) % 2 != 0
var zag = pt[2] > 0 ? parseInt(Math.abs(pt[2])/50) % 2 == 0 : parseInt(Math.abs(pt[2])/50) % 2 != 0
if(!zig != !zag)// zig XOR zag
return this.col1;
return this.col2;
}
}
rays.Camera = function(location, lookat, angle, width, height, up){
this.up = up || [0.0,1.0,0.0];
this.location = location;
this.lookat = lookat;
this.angle = angle;
this.camz = plib.v3.normalise(plib.v3.sub(lookat, location));
this.camx = plib.v3.normalise(plib.v3.cross(this.up, this.camz));
this.camy = plib.v3.normalise(plib.v3.cross(this.camx, plib.v3.sub([0,0,0], this.camz)));
this.tax = Math.tan(angle);
this.tay = Math.tan((height/width) * angle)
this.getRay = function(x,y){
var xdir = plib.v3.scale(this.camx, (x - 0.5) * this.tax);
var ydir = plib.v3.scale(this.camy, (y - 0.5) * this.tay);
var pt = plib.v3.add(this.camz, plib.v3.add(xdir, ydir));
//postMessage("DBG2 " + this.location + " | " +pt + " | " + plib.v3.sub(pt, this.location) );
return [this.location, pt]
}
}
rays.intToColor = function(i){
var c = [i % 256, (i>>8) % 256, (i>>16) % 256]
return 'rgb(' + parseInt(c[0]) + "," + parseInt(c[1]) + "," + parseInt(c[2]) + ')';
}
rays.pixelToInt = function(c){
c[0] = Math.max(0, Math.min(c[0], 255));
c[1] = Math.max(0, Math.min(c[1], 255));
c[2] = Math.max(0, Math.min(c[2], 255));
return parseInt(c[0] + (c[1] << 8) + (c[2] << 16));
}
rays.intAsHex = function(i){
return i.toString(16);
}
rays.intAsChar = function(i){
return i.toString(36);
}
rays.encodeLine = function(line){
//Diff Encoding & Run Length encoding
var out = []
var rl = 0;
var prev = 0;
for(var i =0; i<line.length; i++){
if (line[i] == prev){
rl +=1;
}else{
if (rl !=0 ){
out.push("_");
out.push(rl);
rl = 0;
}
out.push(rays.intAsChar(line[i] - prev));
prev = line[i];
}
}
if (rl !=0 ){
out.push("_");
out.push(rl);
rl = 0;
}
return out.join(",");
}
rays.decodeLine = function(line){
var x = line.split(",");
var out = [];
var prev = 0;
for(var i =0;i<line.length; i++){
var c = x[i];
if(c == "_"){
for (var j = 0; j<parseInt(x[i+1]); j++){
out.push(prev);
}
i +=1;
} else{
var y = parseInt(c, 36);
out.push(y + prev);
prev = y + prev;
}
}
return out;
}
/**
* Determine whether the ray from ro->rd intersects an object and if so return the nearest distance and object
*/
rays.intersection = function(ro, rd, max, min){
var min = min || 0.0;
var nearest = null;
var nearest_dist = max;
$.each(rays.scene.objects, function(){
var d = this.intersects(ro, rd);
if(d && d < nearest_dist && d > min){
nearest_dist = d;
nearest = this;
}
});
return [nearest_dist, nearest];
}
/**
* Trace a ray (ro->rd) through the scene
*/
rays.trace = function(ro, rd, depth){
var depth = depth || 0
var i = rays.intersection(ro,rd, 1.0E100000);
var nearest = i[1];
var dist = i[0];
if (nearest){
var intersection_point = plib.v3.add(ro, plib.v3.scale(plib.v3.normalise(rd), dist));
var normal = nearest.normal(intersection_point);
//Ambient
var col_scale = rays.ambient;
var specs = [0,0,0];
$.each(rays.scene.lights, function(){
var lvec = plib.v3.sub(this[0], intersection_point)
var shadow = rays.intersection(intersection_point, lvec, plib.v3.len(lvec), 0.05);
if (!shadow[1]) {
//Diffuse (Lambertian)
var diff_scale = plib.v3.dot(plib.v3.normalise(lvec), normal) * this[1]
if (diff_scale > 0){
col_scale += diff_scale;
}
/* Someone hire me and get me to do something productive :) */
//Specular
var i = plib.v3.normalise(lvec);
var r = plib.v3.sub(i, plib.v3.scale(normal, 2.0*plib.v3.dot(normal, i)));
var dp = plib.v3.dot(r, plib.v3.normalise(rd))
if (dp >0){
var spec_scale = Math.pow(dp, nearest.phong)
if (spec_scale > 0){
specs = plib.v3.add(specs, plib.v3.scale(this[2], spec_scale*this[1]))
}
}
}
});
var col = plib.v3.add(plib.v3.scale(nearest.color(intersection_point), col_scale), specs);
//Reflection
if (nearest.reflection && depth<rays.max_depth){
var r = plib.v3.sub(rd, plib.v3.scale(normal, 2.0*plib.v3.dot(normal, rd)));
var refl = rays.trace(intersection_point, r ,depth+1)
col = plib.v3.add(plib.v3.scale(col, 1 - nearest.reflection),
plib.v3.scale(refl, nearest.reflection))
}
return col
}
else{
/* No intersection, background color */
return [0,0,0];
}
}
rays.getRay = function(x,y, width, height){
return plib.v3.sub([x - width/2, y - height/2, rays.cam_dist], rays.eye);
}
/**
* Map renders a single line of the image
*
* This is probably the right sort of size chunk of computation.
*
* Args is [ymin, ymax, xmin, xmax, screenwidth, screenheight]
*/
rays.map = function(args, callback){
var x = args[2];
var y = args[0];
var busy = false;
var res = [];
var i = 0;
//Because a line may take a while, setInterval to allow other computation
var kill_iter = false; //Screw Firefox's crappy worker implementation
var iter = setInterval(function(){
if (!busy && !kill_iter){
busy = true;
if (x >= args[3] && y>=args[1]){
clearInterval(iter);
callback(args, rays.encodeLine(res));
busy = false;
kill_iter = true;
}
if (rays.antialias){
var tot = [0.0,0.0,0.0];
var rot_grid = [[0.2, 0.2], [0.2, 0.8], [0.8, 0.2], [0.8, 0.8]];
for(var s = 0; s < rot_grid.length; s++){
var ray = rays.scene.camera.getRay((x + rot_grid[s][0])/(0.0 + args[3]),(y + rot_grid[s][1])/(0.0 + args[4]));
var col = rays.trace(ray[0], ray[1]);
tot = plib.v3.add(tot, col);
}
res[i] = rays.pixelToInt(plib.v3.scale(tot, 1.0/(4.0)));
//postMessage("DBG: " + ray1 + " | " + ray2 + " | " + res[i] + " -> " + x + ", " + y);
}else{
var ray = rays.scene.camera.getRay(x/(0.0 + args[3]),y/(0.0 + args[4]));
res[i] = rays.pixelToInt(rays.trace(ray[0], ray[1]));
}
if (x>=args[3]){
y++;
x = args[2];
}else{
x ++;
}
i ++;
busy = false;
}
},0);
}
/**
* Distribute each pixel
*/
rays.renderImage = function(screen, ctx){
var x = 0;
var y = 0;
var busy = false;
var rint = setInterval(function(){
if (!busy){
busy = true;
//Update Stats
//if(x%100 == 0){
//$("#rpx").text(x);
//$("#rpy").text(y);
// $("#progress").text(parseInt((x*y)/(screen.width*screen.height)*100));
//}
//Trace Ray
var ray = plib.v3.sub([x - screen.width/2, y - screen.height/2, rays.cam_dist], rays.eye);
var col = rays.trace(rays.eye, ray);
ctx.fillStyle = 'rgb(' + parseInt(col[0]) + "," + parseInt(col[1]) + "," + parseInt(col[2]) + ')';
ctx.fillRect (x,screen.height-y,1,1);
//Update 'loop'
if(x<screen.width-1){
x +=1;
}else{
x = 0;
if (y<screen.height-1){
y +=1;
}else{
clearInterval(rint);
}
}
busy = false;
}
},0);
}
localProcess = function(data){
var run = function(ind){
if (ind >= data.length){
return
}
console.log("Rendering Line", ind);
rays.map(data[ind], function(args, res){
rays.handleResult([{'args' : args, 'res' : res}], function(){
run(++ind);
});
});
}
run(0);
}
/* Render the result */
rays.handleResult = function(rows, callback){
var scrn = $("#rays")[0];
var ctx = scrn.getContext('2d');
$.each(rows, function(){
args = this['args'];
data = rays.decodeLine(this['res']);
var y = args[0];
//if ($.inArray(y, rays.rendered) < 0){
// rays.rendered.push(y);
var x = args[2]
for(var i = 0; y<args[1]; i++){
var c = rays.intToColor(data[i]);
ctx.fillStyle = c;
ctx.fillRect (x,scrn.height-y,1,1);
if (x >= args[3]){
y ++;
x = args[2];
} else{
x++;
}
}
//}
});
if (callback){
return callback();
}
}
//rays.rendered = [];
/** Scene Params **/
rays.eye = [0,0,0];
rays.cam_dist = 200; /* Cam plane is x,y,cam_dist */
rays.ambient = 0.1;
rays.max_depth = 1;
rays.antialias = 4;//Num samples
rays.scene = {}
rays.scene.objects = [
new rays.Sphere(pos = [3.0,5.0,5.0], radius = 5.0, color = [0xff,0,0], phong = 20, reflection = 0.2),
new rays.Sphere(pos = [0,5.0,0], radius = 5.0, color = [0,0,0xff], phong = 20, reflection = 0.2),
new rays.Sphere(pos = [-3.0,5.0, 5.0], radius = 5.0, color = [0x00,0xff,0x00], phong = 30, reflection = 0.2),
new rays.CheckerYPlane(0.0, [0x33,0x33,0x33], [0xdd,0xdd,0xdd])
];
rays.scene.lights = [
/* [[x,y,z], intensity(0-1), color] */
[[-300,300,0], 0.9, [0xff, 0xff, 0xff]]
]
rays.scene.camera = new rays.Camera([0.0,10.0,-50.0], [0.0,5.0,0.0], Math.PI/4, 5, 4);
/** Onload setup the canvas and do shizzle **/
$(function(){
var screen = $("#rays")[0];
var ctx = screen.getContext('2d');
ctx.fillStyle = "#555";
ctx.fillRect (0, 0, screen.width, screen.height);
var data = plib.forRange(
function(x){
return [x, x+1, 0, screen.width, screen.width, screen.height];
},
0, screen.height
);
$("#start_raytracer").click(function(){
localProcess(data);
});
});
</script>
</body>
</html>