raytracer-worker.js

self.addEventListener('message', function (e) {

    var canvas = e.data[0];
    var ctx = canvas.getContext('2d');
    var imgData = ctx.createImageData(canvas.width, canvas.height);
    var maxdepth = e.data[2];
    var lights = e.data[3];
function intersect(x1, y1, x2, y2, x3, y3, x4, y4) {
    var a1, a2, b1, b2, c1, c2;
    var r1, r2, r3, r4;
    var denom, offset, num;

    a1 = y2 - y1;
    b1 = x1 - x2;
    c1 = (x2 * y1) - (x1 * y2);
    r3 = ((a1 * x3) + (b1 * y3) + c1);
    r4 = ((a1 * x4) + (b1 * y4) + c1);


    a2 = y4 - y3;
    b2 = x3 - x4;
    c2 = (x4 * y3) - (x3 * y4);
    r1 = (a2 * x1) + (b2 * y1) + c2;
    r2 = (a2 * x2) + (b2 * y2) + c2;

    denom = (r1 * r2) - (r3 * r4);
    if (denom == 0) {
        return false;
    }

    offset = Math.abs(denom / 2);

    num = (r1 * r4) - (r2 * r3);
    var x = (num < 0) ? ((num - offset) / denom) : ((num + offset) / denom);

    num = (a1 * r4) - (a2 * r3);
    var y = (num < 0) ? ((num - offset) / denom) : ((num + offset) / denom);

    var point = new Point(x, y);

    if (r1 == 0 || r2 == 0 || r3 == 0 || r4 == 0) {
        return true;
    } else {
        return (r1 > 0 && r2 > 0 && r3 > 0 && r4 > 0) ||
            (r1 < 0 && r2 < 0 && r3 < 0 && r4 < 0);
    }
}
function typedArrayToURL(typedArray, mimeType) {
    return URL.createObjectURL(new Blob([typedArray.buffer], {type: mimeType}))
  }


function trace(scene, ray, lights, depth) {
    // check if the ray hits an object
    // if so, calculate the color
    // if not, return the background color
    // check if the ray hits an object

    var closest = findIntersection(scene.objects, ray);
    if (closest) {
        var point = ray.origin.add(ray.direction.multiply(closest.distance));
        var normal = closest.object.normalAt(point);
        var lambertAmount = 0;

        for (var i = 0; i < lights.length; i++) {
            var lightDirection = lights[i].position.subtract(point).normalize();
            var shadowOrigin = lightDirection.dot(normal) < 0 ? point.subtract(normal.multiply(1e-3)) : point.add(normal.multiply(1e-3));
            var shadowRay = new Ray(shadowOrigin, lightDirection);
            var inShadow = findIntersection(scene.objects, shadowRay);
            if (inShadow && inShadow.distance < lights[i].position.subtract(shadowOrigin).magnitude()) {
                lambertAmount = 0;
            }
            else {
                lambertAmount += lights[i].intensity * Math.max(0, lightDirection.dot(normal));
            }
        }
        var color = closest.object.color;
        var finalColor = color.multiply(scene.ambientLight).add(color.multiply(lambertAmount));
        var specularAmount = 0;
        var reflectDirection = ray.direction.subtract(normal.multiply(2 * ray.direction.dot(normal))).normalize();
        var reflectRay = new Ray(point.add(reflectDirection.multiply(1e-3)), reflectDirection);
        var reflectColor = trace(scene, reflectRay, lights, depth + 1);
        if (reflectColor && depth <= maxDepth) {
            specularAmount = Math.pow(Math.max(0, -reflectDirection.dot(ray.direction)), closest.object.specularExponent);
        }
        finalColor = finalColor.add(reflectColor.multiply(closest.object.reflectivity).multiply(specularAmount));
        return finalColor;
    }
    else {
        return null;
    }
}

function findIntersection(objects, ray) {
    var closest = Infinity;
    var closestInter = null;
    for (var i = 0; i < objects.length; i++) {
        var inter = objects[i].intersect(ray);
        if (inter != null && inter.distance < closest) {
            closestInter = inter;
            closest = inter.distance;
        }
    }
    return closestInter;
}
    for (var i = 0; i < e.data[4].length; i++) {
        var ray = e.data[4][i];
        var color = trace(e.data[1], ray, lights, maxdepth);
        if (color) {
            imgData.data[i * 4] = color[0];
            imgData.data[i * 4 + 1] = color[1];
            imgData.data[i * 4 + 2] = color[2];
        }
    }
    ctx.putImageData(imgData, 0, 0);
    postMessage("Finished");
}, false);