// if no object is hit, draw a gradient
static Vector3 color(Ray r, Hitable world, int depth)
{
hit_record rec = new hit_record();
// see if an object is hit
if (world.hit(r, 0.001f, float.MaxValue, ref rec))
{
// shade the indicated point
Ray scattered = new Ray();
Vector3 attenuation = new Vector3();
if (depth < 50 && rec.mat.scatter(r, rec, ref attenuation, ref scattered))
{
return(attenuation * color(scattered, world, depth + 1));
}
else
{
// reached our max depth, don't render any further
return(new Vector3());
}
}
else
{
// no object hit, draw the background
Vector3 unit_dir = r.direction().unit_vector();
float t = 0.5f * (unit_dir.y() + 1.0f);
return((new Vector3(1.0f, 1.0f, 1.0f)) * (1.0f - t) + (new Vector3(0.5f, 0.7f, 1.0f) * t));
}
}
public BVH_Node(List <Hitable> l, float t0, float t1)
{
// randomly select an axis to sort child nodes by
int axis = Utils.rnd.Next(3);
if (axis == 0)
{
//x
l.Sort(Utils.hitable_box_compare_x);
}
else if (axis == 1)
{
//y
l.Sort(Utils.hitable_box_compare_y);
}
else
{
//z
l.Sort(Utils.hitable_box_compare_z);
}
// build the tree
if (l.Count == 1)
{
left = l [0];
right = l [0];
}
else if (l.Count == 2)
{
left = l [0];
right = l [1];
}
else
{
List <Hitable> l_hitables = l.GetRange(0, (int)Math.Floor(l.Count / 2.0f) + 1);
List <Hitable> r_hitables = l.GetRange(l_hitables.Count, l.Count - l_hitables.Count);
left = new BVH_Node(l_hitables, t0, t1);
right = new BVH_Node(r_hitables, t0, t1);
}
AABB box_left = new AABB();
AABB box_right = new AABB();
// ensure that there is a possible bounding box before continuing
if (!left.bounding_box(t0, t1, ref box_left) || !right.bounding_box(t0, t1, ref box_right))
{
Console.Error.WriteLine("No possible bounding box in BVH constructor!");
List <Hitable> l_hitables = l.GetRange(0, (int)Math.Floor(l.Count / 2.0f) + 1);
List <Hitable> r_hitables = l.GetRange(l_hitables.Count, l.Count - l_hitables.Count);
Console.Error.WriteLine(l_hitables.Count + " " + r_hitables.Count);
}
box = AABB.surrounding_box(box_left, box_right);
}
// used for comparing bounding boxes of two hitables
public static int hitable_box_compare_x(Hitable a, Hitable b)
{
AABB box_left = new AABB();
AABB box_right = new AABB();
if (!a.bounding_box(0.0f, 0.0f, ref box_left) || !b.bounding_box(0.0f, 0.0f, ref box_right))
{
Console.Error.WriteLine("No possible bounding box during x comparison");
}
if (box_left.min().x() - box_right.min().x() < 0.0f)
{
return(-1);
}
else
{
return(1);
}
}
private static Vec3 Color(Ray r, Hitable world, int depth)
{
HitRecord rec = new HitRecord();
if (world.Hit(r, 0.001, double.MaxValue, out rec))
{
Ray scattered = new Ray();
Vec3 attenuation = new Vec3();
Vec3 emitted = rec.Material.emitted(rec.U, rec.V, rec.P);
if (depth < 50 && rec.Material.Scatter(r, rec, out attenuation, out scattered))
{
return(emitted + attenuation * Color(scattered, world, depth + 1));
}
else
{
return(emitted);
}
}
else
{
return(new Vec3(0.0, 0.0, 0.0));
}
}