/*

 * Copyright (C) 2007 Apple Inc.  All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 *

 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY

 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR

 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR

 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY

 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 

 */

function createVector(x,y,z) {

    return new Array(x,y,z);

}

function sqrLengthVector(self) {

    return self[0] * self[0] + self[1] * self[1] + self[2] * self[2];

}

function lengthVector(self) {

    return Math.sqrt(self[0] * self[0] + self[1] * self[1] + self[2] * self[2]);

}

function addVector(self, v) {

    self[0] += v[0];

    self[1] += v[1];

    self[2] += v[2];

    return self;

}

function subVector(self, v) {

    self[0] -= v[0];

    self[1] -= v[1];

    self[2] -= v[2];

    return self;

}

function scaleVector(self, scale) {

    self[0] *= scale;

    self[1] *= scale;

    self[2] *= scale;

    return self;

}

function normaliseVector(self) {

    var len = Math.sqrt(self[0] * self[0] + self[1] * self[1] + self[2] * self[2]);

    self[0] /= len;

    self[1] /= len;

    self[2] /= len;

    return self;

}

function add(v1, v2) {

    return new Array(v1[0] + v2[0], v1[1] + v2[1], v1[2] + v2[2]);

}

function sub(v1, v2) {

    return new Array(v1[0] - v2[0], v1[1] - v2[1], v1[2] - v2[2]);

}

function scalev(v1, v2) {

    return new Array(v1[0] * v2[0], v1[1] * v2[1], v1[2] * v2[2]);

}

function dot(v1, v2) {

    return v1[0] * v2[0] + v1[1] * v2[1] + v1[2] * v2[2];

}

function scale(v, scale) {

    return [v[0] * scale, v[1] * scale, v[2] * scale];

}

function cross(v1, v2) {

    return [v1[1] * v2[2] - v1[2] * v2[1], 

            v1[2] * v2[0] - v1[0] * v2[2],

            v1[0] * v2[1] - v1[1] * v2[0]];

}

function normalise(v) {

    var len = lengthVector(v);

    return [v[0] / len, v[1] / len, v[2] / len];

}

function transformMatrix(self, v) {

    var vals = self;

    var x  = vals[0] * v[0] + vals[1] * v[1] + vals[2] * v[2] + vals[3];

    var y  = vals[4] * v[0] + vals[5] * v[1] + vals[6] * v[2] + vals[7];

    var z  = vals[8] * v[0] + vals[9] * v[1] + vals[10] * v[2] + vals[11];

    return [x, y, z];

}

function invertMatrix(self) {

    var temp = new Array(16);

    var tx = -self[3];

    var ty = -self[7];

    var tz = -self[11];

    for (h = 0; h < 3; h++) 

        for (v = 0; v < 3; v++) 

            temp[h + v * 4] = self[v + h * 4];

    for (i = 0; i < 11; i++)

        self[i] = temp[i];

    self[3] = tx * self[0] + ty * self[1] + tz * self[2];

    self[7] = tx * self[4] + ty * self[5] + tz * self[6];

    self[11] = tx * self[8] + ty * self[9] + tz * self[10];

    return self;

}

// Triangle intersection using barycentric coord method

function Triangle(p1, p2, p3) {

    var edge1 = sub(p3, p1);

    var edge2 = sub(p2, p1);

    var normal = cross(edge1, edge2);

    if (Math.abs(normal[0]) > Math.abs(normal[1]))

        if (Math.abs(normal[0]) > Math.abs(normal[2]))

            this.axis = 0; 

        else 

            this.axis = 2;

    else

        if (Math.abs(normal[1]) > Math.abs(normal[2])) 

            this.axis = 1;

        else 

            this.axis = 2;

    var u = (this.axis + 1) % 3;

    var v = (this.axis + 2) % 3;

    var u1 = edge1[u];

    var v1 = edge1[v];

    var u2 = edge2[u];

    var v2 = edge2[v];

    this.normal = normalise(normal);

    this.nu = normal[u] / normal[this.axis];

    this.nv = normal[v] / normal[this.axis];

    this.nd = dot(normal, p1) / normal[this.axis];

    var det = u1 * v2 - v1 * u2;

    this.eu = p1[u];

    this.ev = p1[v]; 

    this.nu1 = u1 / det;

    this.nv1 = -v1 / det;

    this.nu2 = v2 / det;

    this.nv2 = -u2 / det; 

    this.material = [0.7, 0.7, 0.7];

}

Triangle.prototype.intersect = function(orig, dir, near, far) {

    var u = (this.axis + 1) % 3;

    var v = (this.axis + 2) % 3;

    var d = dir[this.axis] + this.nu * dir[u] + this.nv * dir[v];

    var t = (this.nd - orig[this.axis] - this.nu * orig[u] - this.nv * orig[v]) / d;

    if (t < near || t > far)

        return null;

    var Pu = orig[u] + t * dir[u] - this.eu;

    var Pv = orig[v] + t * dir[v] - this.ev;

    var a2 = Pv * this.nu1 + Pu * this.nv1;

    if (a2 < 0) 

        return null;

    var a3 = Pu * this.nu2 + Pv * this.nv2;

    if (a3 < 0) 

        return null;

    if ((a2 + a3) > 1) 

        return null;

    return t;

}

function Scene(a_triangles) {

    this.triangles = a_triangles;

    this.lights = [];

    this.ambient = [0,0,0];

    this.background = [0.8,0.8,1];

}

var zero = new Array(0,0,0);

Scene.prototype.intersect = function(origin, dir, near, far) {

    var closest = null;

    for (i = 0; i < this.triangles.length; i++) {

        var triangle = this.triangles[i];   

        var d = triangle.intersect(origin, dir, near, far);

        if (d == null || d > far || d < near)

            continue;

        far = d;

        closest = triangle;

    }

    if (!closest)

        return [this.background[0],this.background[1],this.background[2]];

    var normal = closest.normal;

    var hit = add(origin, scale(dir, far)); 

    if (dot(dir, normal) > 0)

        normal = [-normal[0], -normal[1], -normal[2]];

    var colour = null;

    if (closest.shader) {

        colour = closest.shader(closest, hit, dir);

    } else {

        colour = closest.material;

    }

    // do reflection

    var reflected = null;

    if (colour.reflection > 0.001) {

        var reflection = addVector(scale(normal, -2*dot(dir, normal)), dir);

        reflected = this.intersect(hit, reflection, 0.0001, 1000000);

        if (colour.reflection >= 0.999999)

            return reflected;

    }

    var l = [this.ambient[0], this.ambient[1], this.ambient[2]];

    for (var i = 0; i < this.lights.length; i++) {

        var light = this.lights[i];

        var toLight = sub(light, hit);

        var distance = lengthVector(toLight);

        scaleVector(toLight, 1.0/distance);

        distance -= 0.0001;

        if (this.blocked(hit, toLight, distance))

            continue;

        var nl = dot(normal, toLight);

        if (nl > 0)

            addVector(l, scale(light.colour, nl));

    }

    l = scalev(l, colour);

    if (reflected) {

        l = addVector(scaleVector(l, 1 - colour.reflection), scaleVector(reflected, colour.reflection));

    }

    return l;

}

Scene.prototype.blocked = function(O, D, far) {

    var near = 0.0001;

    var closest = null;

    for (i = 0; i < this.triangles.length; i++) {

        var triangle = this.triangles[i];   

        var d = triangle.intersect(O, D, near, far);

        if (d == null || d > far || d < near)

            continue;

        return true;

    }

    return false;

}

// this camera code is from notes i made ages ago, it is from *somewhere* -- i cannot remember where

// that somewhere is

function Camera(origin, lookat, up) {

    var zaxis = normaliseVector(subVector(lookat, origin));

    var xaxis = normaliseVector(cross(up, zaxis));

    var yaxis = normaliseVector(cross(xaxis, subVector([0,0,0], zaxis)));

    var m = new Array(16);

    m[0] = xaxis[0]; m[1] = xaxis[1]; m[2] = xaxis[2];

    m[4] = yaxis[0]; m[5] = yaxis[1]; m[6] = yaxis[2];

    m[8] = zaxis[0]; m[9] = zaxis[1]; m[10] = zaxis[2];

    invertMatrix(m);

    m[3] = 0; m[7] = 0; m[11] = 0;

    this.origin = origin;

    this.directions = new Array(4);

    this.directions[0] = normalise([-0.7,  0.7, 1]);

    this.directions[1] = normalise([ 0.7,  0.7, 1]);

    this.directions[2] = normalise([ 0.7, -0.7, 1]);

    this.directions[3] = normalise([-0.7, -0.7, 1]);

    this.directions[0] = transformMatrix(m, this.directions[0]);

    this.directions[1] = transformMatrix(m, this.directions[1]);

    this.directions[2] = transformMatrix(m, this.directions[2]);

    this.directions[3] = transformMatrix(m, this.directions[3]);

}

Camera.prototype.generateRayPair = function(y) {

    rays = new Array(new Object(), new Object());

    rays[0].origin = this.origin;

    rays[1].origin = this.origin;

    rays[0].dir = addVector(scale(this.directions[0], y), scale(this.directions[3], 1 - y));

    rays[1].dir = addVector(scale(this.directions[1], y), scale(this.directions[2], 1 - y));

    return rays;

}

function renderRows(camera, scene, pixels, width, height, starty, stopy) {

    for (var y = starty; y < stopy; y++) {

        var rays = camera.generateRayPair(y / height);

        for (var x = 0; x < width; x++) {

            var xp = x / width;

            var origin = addVector(scale(rays[0].origin, xp), scale(rays[1].origin, 1 - xp));

            var dir = normaliseVector(addVector(scale(rays[0].dir, xp), scale(rays[1].dir, 1 - xp)));

            var l = scene.intersect(origin, dir);

            pixels[y][x] = l;

        }

    }

}

Camera.prototype.render = function(scene, pixels, width, height) {

    var cam = this;

    var row = 0;

    renderRows(cam, scene, pixels, width, height, 0, height);

}

function raytraceScene()

{

    var startDate = new Date().getTime();

    var numTriangles = 2 * 6;

    var triangles = new Array();//numTriangles);

    var tfl = createVector(-10,  10, -10);

    var tfr = createVector( 10,  10, -10);

    var tbl = createVector(-10,  10,  10);

    var tbr = createVector( 10,  10,  10);

    var bfl = createVector(-10, -10, -10);

    var bfr = createVector( 10, -10, -10);

    var bbl = createVector(-10, -10,  10);

    var bbr = createVector( 10, -10,  10);

    // cube!!!

    // front

    var i = 0;

    triangles[i++] = new Triangle(tfl, tfr, bfr);

    triangles[i++] = new Triangle(tfl, bfr, bfl);

    // back

    triangles[i++] = new Triangle(tbl, tbr, bbr);

    triangles[i++] = new Triangle(tbl, bbr, bbl);

    //        triangles[i-1].material = [0.7,0.2,0.2];

    //            triangles[i-1].material.reflection = 0.8;

    // left

    triangles[i++] = new Triangle(tbl, tfl, bbl);

    //            triangles[i-1].reflection = 0.6;

    triangles[i++] = new Triangle(tfl, bfl, bbl);

    //            triangles[i-1].reflection = 0.6;

    // right

    triangles[i++] = new Triangle(tbr, tfr, bbr);

    triangles[i++] = new Triangle(tfr, bfr, bbr);

    // top

    triangles[i++] = new Triangle(tbl, tbr, tfr);

    triangles[i++] = new Triangle(tbl, tfr, tfl);

    // bottom

    triangles[i++] = new Triangle(bbl, bbr, bfr);

    triangles[i++] = new Triangle(bbl, bfr, bfl);

    //Floor!!!!

    var green = createVector(0.0, 0.4, 0.0);

    var grey = createVector(0.4, 0.4, 0.4);

    grey.reflection = 1.0;

    var floorShader = function(tri, pos, view) {

        var x = ((pos[0]/32) % 2 + 2) % 2;

        var z = ((pos[2]/32 + 0.3) % 2 + 2) % 2;

        if (x < 1 != z < 1) {

            //in the real world we use the fresnel term...

            //    var angle = 1-dot(view, tri.normal);

            //   angle *= angle;

            //  angle *= angle;

            // angle *= angle;

            //grey.reflection = angle;

            return grey;

        } else 

            return green;

    }

    var ffl = createVector(-1000, -30, -1000);

    var ffr = createVector( 1000, -30, -1000);

    var fbl = createVector(-1000, -30,  1000);

    var fbr = createVector( 1000, -30,  1000);

    triangles[i++] = new Triangle(fbl, fbr, ffr);

    triangles[i-1].shader = floorShader;

    triangles[i++] = new Triangle(fbl, ffr, ffl);

    triangles[i-1].shader = floorShader;

    var _scene = new Scene(triangles);

    _scene.lights[0] = createVector(20, 38, -22);

    _scene.lights[0].colour = createVector(0.7, 0.3, 0.3);

    _scene.lights[1] = createVector(-23, 40, 17);

    _scene.lights[1].colour = createVector(0.7, 0.3, 0.3);

    _scene.lights[2] = createVector(23, 20, 17);

    _scene.lights[2].colour = createVector(0.7, 0.7, 0.7);

    _scene.ambient = createVector(0.1, 0.1, 0.1);

    //  _scene.background = createVector(0.7, 0.7, 1.0);

    var size = 30;

    var pixels = new Array();

    for (var y = 0; y < size; y++) {

        pixels[y] = new Array();

        for (var x = 0; x < size; x++) {

            pixels[y][x] = 0;

        }

    }

    var _camera = new Camera(createVector(-40, 40, 40), createVector(0, 0, 0), createVector(0, 1, 0));

    _camera.render(_scene, pixels, size, size);

    return pixels;

}

function arrayToCanvasCommands(pixels)

{

    var s = '<canvas id="renderCanvas" width="30px" height="30px"></canvas><scr' + 'ipt>\nvar pixels = [';

    var size = 30;

    for (var y = 0; y < size; y++) {

        s += "[";

        for (var x = 0; x < size; x++) {

            s += "[" + pixels[y][x] + "],";

        }

        s+= "],";

    }

    s += '];\n    var canvas = document.getElementById("renderCanvas").getContext("2d");\n\

\n\

\n\

    var size = 30;\n\

    canvas.fillStyle = "red";\n\

    canvas.fillRect(0, 0, size, size);\n\

    canvas.scale(1, -1);\n\

    canvas.translate(0, -size);\n\

\n\

    if (!canvas.setFillColor)\n\

        canvas.setFillColor = function(r, g, b, a) {\n\

            this.fillStyle = "rgb("+[Math.floor(r * 255), Math.floor(g * 255), Math.floor(b * 255)]+")";\n\

    }\n\

\n\

for (var y = 0; y < size; y++) {\n\

  for (var x = 0; x < size; x++) {\n\

    var l = pixels[y][x];\n\

    canvas.setFillColor(l[0], l[1], l[2], 1);\n\

    canvas.fillRect(x, y, 1, 1);\n\

  }\n\

}</scr' + 'ipt>';

    return s;

}

testOutput = arrayToCanvasCommands(raytraceScene());