function R(B){function d(a,b,d){return{x:a,y:b,z:d,w:1}}function p(a,b){return d(a.x*b,a.y*b,a.z*b)}function m(a,b){return d(a.x-b.x,a.y-b.y,a.z-b.z)}function v(a,b){return a.x*b.x+a.y*b.y+a.z*b.z}function w(a){return p(a,1/C(a.x*a.x+a.y*a.y+a.z*a.z))}function D(a,b){for(var d=9,f,h,k,e,g,l;d--;)f=3*d,k=t[f+1],e=m(a,t[f]),g=v(b,b)/2,l=-2*v(e,b),k=(l-C(l*l-8*g*(v(e,e)-k*k)))*g,.1<k&&(!h||k<h.d)&&(h={i:f,d:k});return h}function E(){for(var a=B.createImageData(f,1),b=0,n=f,r,h,k,e,g,l;n--;){h=F;for(k=
32;k--;)e=w(m(d(0,u-n+q(),u-x+q()),y)),g=D(y,e),l=z,g&&(e=p(e,g.d),e=m(y,p(e,-1)),l=D(e,w(m(G,e)))?F:g.i?p(t[g.i+2],A.max(v(w(m(G,e)),w(m(e,t[g.i]))),0)):z),g=p(l,.03125),h=m(h,p(g,-1));for(r in h)a.data[b++]=255*h[r]}B.putImageData(a,1,x);x++<f&&setTimeout(E,0)}function n(a,b){return q()*(b-a)+a}for(var A=Math,C=A.sqrt,q=A.random,f=512,u=f/2,y=d(f,0,0),G=d(f,n(-f,f),f),z=d(.8,.8,.8),F=d(0,0,0),t=[d(0,0,-1000075),1E6,z],x=1,H=8,r;H--;)r=n(20,60),t.push(d(n(-f,u),n(-u,u),r-75),r,d(q(),q(),q()));E()}
R(c);
function R (context)
{
function Vector (x, y, z)
{
// w component is for rgba usage
return {x : x, y : y, z : z, w : 1};
}
function Mul (a, b)
{
return Vector (a.x * b, a.y * b, a.z * b);
}
function Add (a, b)
{
return Sub (a, Mul (b, -1));
}
function Sub (a, b)
{
return Vector (a.x - b.x, a.y - b.y, a.z - b.z);
}
function Dot (a, b)
{
return a.x * b.x + a.y * b.y + a.z * b.z;
}
function Normalize (a)
{
return Mul (a, 1 / mySqrt (a.x * a.x + a.y * a.y + a.z * a.z));
}
function RayModelIntersection (rayOrigin, rayDirection)
{
var sphereIndex = 9,
currentIndex, result, sphereRadius,
sphereToRay, a, b, minT;
// check intersection with every sphere in the scene
while (sphereIndex--) {
// check ray-sphere intersection
currentIndex = 3 * sphereIndex;
sphereRadius = geometry[currentIndex + 1];
sphereToRay = Sub (rayOrigin, geometry[currentIndex]);
a = Dot (rayDirection, rayDirection) / 2;
b = -2 * Dot (sphereToRay, rayDirection);
minT = (b - mySqrt (b * b - 8 * a * (Dot (sphereToRay, sphereToRay) - sphereRadius * sphereRadius))) * a;
// in case of negative discriminant minT is NaN, and it is not greater than 0.1 :)
if (minT > 0.1 && (!result || minT < result.d)) {
result = {i : currentIndex, d : minT};
}
}
return result;
}
function RenderRowsOneStep ()
{
var sampleCount = 32,
imageData = context.createImageData (canvasSize, 1),
imageDataIndex = 0,
columnIndex = canvasSize,
componentIndex, tracedColor, currentSample,
rayDirection, intersection, shadedColor, intersectionPoint;
while (columnIndex--) {
tracedColor = blackColor;
currentSample = sampleCount;
// shoot random rays through the pixel
while (currentSample--) {
rayDirection = Normalize (
Sub (
Vector (0, halfCanvasSize - columnIndex + myRandom (), halfCanvasSize - rowIndex + myRandom ()),
eyePosition
)
);
intersection = RayModelIntersection (eyePosition, rayDirection);
shadedColor = backgroundColor;
if (intersection) {
intersectionPoint = Add (eyePosition, Mul (rayDirection, intersection.d));
// do the shading for intersection point (no shading for the large sphere)
shadedColor = RayModelIntersection (intersectionPoint, Normalize (Sub (lightPosition, intersectionPoint))) ?
blackColor : // in shadow
intersection.i ? // not the first large sphere
Mul (
geometry[intersection.i + 2], // sphere color
M.max (
Dot (
Normalize (Sub (lightPosition, intersectionPoint)), // direction to the light source
Normalize (Sub (intersectionPoint, geometry[intersection.i])) // sphere normal vector
),
0.0
) // diffuse intensity
) :
backgroundColor; // first large sphere
}
tracedColor = Add (tracedColor, Mul (shadedColor, 1 / sampleCount));
}
for (componentIndex in tracedColor) {
imageData.data[imageDataIndex++] = tracedColor[componentIndex] * 255;
}
}
context.putImageData (imageData, 1, rowIndex);
if (rowIndex++ < canvasSize) {
setTimeout (RenderRowsOneStep, 0);
}
}
function Random (from, to)
{
return myRandom () * (to - from) + from;
}
var M = Math,
mySqrt = M.sqrt,
myRandom = M.random,
canvasSize = 512,
halfCanvasSize = canvasSize / 2,
eyePosition = Vector (canvasSize, 0, 0),
lightPosition = Vector (canvasSize, Random (-canvasSize, canvasSize), canvasSize),
backgroundColor = Vector (0.8, 0.8, 0.8),
groundSphereRadius = 1000000,
groundOffset = 75,
blackColor = Vector (0, 0, 0),
geometry = [
Vector (0, 0, -groundSphereRadius - groundOffset), groundSphereRadius, backgroundColor
],
rowIndex = 1,
randomSphereCount = 8,
radius;
while (randomSphereCount--) {
radius = Random (20, 60);
geometry.push (Vector (Random (-canvasSize, halfCanvasSize), Random (-halfCanvasSize, halfCanvasSize), radius - groundOffset), radius, Vector (myRandom (), myRandom (), myRandom ()));
}
RenderRowsOneStep ();
}
R (c);
