public BVHNode(Hitable[] list, int low, int high, float t0, float t1)
{
if (low < 0 || high > list.Length)
{
throw new Exception("BVHNode Contruction error low <0 || high >list.Length");
}
int length = high - low;
if (length <= 0)
{
throw new Exception("BVHNode Contruction error low >= high");
}
if (length == 1)
{
_left = _right = list[low];
_box = _left.BoundVolume(t0, t1);
}
else if (length == 2)
{
_left = list[low];
_right = list[low + 1];
_box = AABB.SurroundingBox(_left.BoundVolume(t0, t1), _right.BoundVolume(t0, t1));
}
else
{
Array.Sort(list, low, high - low, new BVHComparer((int)(3 * Exten.rand01())));
int mid = (low + high) / 2;
_left = new BVHNode(list, low, mid, t0, t1);
_right = new BVHNode(list, mid, high, t0, t1);
_box = AABB.SurroundingBox(_left.BoundVolume(t0, t1), _right.BoundVolume(t0, t1));
}
}
static int CmpBVH(Hitable left, Hitable right, int idx)
{
var ab1 = left.BoundVolume(0, 1);
var ab2 = right.BoundVolume(0, 1);
return((int)(ab1._max[idx] - ab2._min[idx]));
}
public AABB BoundVolume(float t0, float t1)
{
return(_inner.BoundVolume(t0, t1));
}
public AABB BoundVolume(float t0, float t1)
{
var b = _inner.BoundVolume(t0, t1);
return(new AABB(b._min + _offset, b._max + _offset));
}