// Normally we'd use double.Epsilon
public static void Main (String[] args, ILog ilog)
{
int n = 0;
if (args.Length > 0)
n = Int32.Parse (args [0]);
Scene scene = Scene.SphereScene (levels, new Vector (0.0, -1.0, 0.0), 1.0);
ilog.InfoFormat ("P5");
ilog.InfoFormat ("{0} {1}", n, n);
ilog.InfoFormat ("255");
Stream stream = Stream.Null;
byte[] temp = new byte[1];
for (int y = n - 1; y >= 0; --y) {
for (int x = 0; x < n; ++x) {
double greyscale = 0.0;
for (int dx = 0; dx < ss; ++dx) {
for (int dy = 0; dy < ss; ++dy) {
Vector v = new Vector (
x + dx / (double)ss - n / 2.0
, y + dy / (double)ss - n / 2.0
, n);
Ray ray = new Ray (new Vector (0.0, 0.0, -4.0), v.Normalized ());
greyscale += scene.TraceRay (ray,
new Vector (-1.0, -3.0, 2.0).Normalized ());
}
}
temp [0] = (byte)(0.5 + 255.0 * greyscale / (ss * ss));
stream.Write (temp, 0, 1);
}
}
}
internal double TraceRay (Ray ray, Vector light)
{
IntersectionPoint p = Intersect (ray,
new IntersectionPoint (
double.PositiveInfinity, new Vector (0.0, 0.0, 0.0)));
if (double.IsInfinity (p.distance))
return 0.0;
double greyscale = -(p.normal * light);
if (greyscale <= 0.0)
return 0.0;
Vector o = ray.origin +
(p.distance * ray.direction) + (Epsilon * p.normal);
Ray shadowRay = new Ray (o, new Vector (0.0, 0.0, 0.0) - light);
IntersectionPoint shadowp = Intersect (shadowRay,
new IntersectionPoint (double.PositiveInfinity, p.normal));
return double.IsInfinity (shadowp.distance) ? greyscale : 0.0;
}
abstract internal IntersectionPoint Intersect (Ray ray, IntersectionPoint p);
override internal IntersectionPoint Intersect (Ray r, IntersectionPoint p)
{
if (bound.Distance (r) < p.distance) {
foreach (Scene each in scenes)
p = each.Intersect (r, p);
}
return p;
}
override internal IntersectionPoint Intersect (Ray r, IntersectionPoint p)
{
double d = Distance (r);
if (d < p.distance) {
Vector v = r.origin + ((d * r.direction) - center);
p = new IntersectionPoint (d, v.Normalized ());
}
return p;
}
internal double Distance (Ray ray)
{
Vector v = center - ray.origin;
double b = v * ray.direction;
double disc = b * b - v * v + radius * radius;
if (disc < 0)
return double.PositiveInfinity; // No intersection
double d = Math.Sqrt (disc);
double t1 = b + d;
if (t1 < 0)
return double.PositiveInfinity;
double t2 = b - d;
return t2 > 0 ? t2 : t1;
}