public BVHNode(Vector3 minBound, Vector3 maxBound, BVHNode leftChild, BVHNode rightChild, int start, int end)
{
bound = new BoundingBox(minBound, maxBound);
lChild = leftChild;
rChild = rightChild;
surfaceIndexStart = start;
surfaceIndexEnd = end;
}
public BVHNode()
{
bound = new BoundingBox();
lChild = null;
rChild = null;
surfaceIndexStart = -1;
surfaceIndexEnd = -1;
}
public void Build(VertexPositionTexture[] verts, int[] inds)
{
tris = new List <Triangle>(inds.Length / 3);
for (int i = 0; i < inds.Length;)
{
int i1 = inds[i++];
int i2 = inds[i++];
int i3 = inds[i++];
tris.Add(new Triangle(
verts[i1].Position,
verts[i2].Position,
verts[i3].Position
));
}
root = CreateTree(0, tris.Count);
}
private BVHNode CreateTree(int start, int end)
{
Vector3 minB = new Vector3(float.MaxValue);
Vector3 maxB = new Vector3(-float.MaxValue);
for (int i = start; i < end; i++)
{
minB = Vector3.Min(tris[i].MinBound, minB);
maxB = Vector3.Max(tris[i].MaxBound, maxB);
}
// Check For Leaf Node Condition
if (end - start <= 1)
{
return(new BVHNode(minB, maxB, null, null, start, end));
}
// Sort On Widest Dimension
Vector3 dim = maxB - minB;
if (dim.X >= dim.Y && dim.X >= dim.Z)
{
tris.Sort(start, end - start, F_SORT_X);
}
else if (dim.Y >= dim.Z)
{
tris.Sort(start, end - start, F_SORT_Y);
}
else
{
tris.Sort(start, end - start, F_SORT_Z);
}
// Create Children
int e = (start + end) / 2;
BVHNode leftChild = CreateTree(start, e);
BVHNode rightChild = CreateTree(e, end);
return(new BVHNode(minB, maxB, leftChild, rightChild, start, end));
}
private bool IntersectHelper(BVHNode node, ref IntersectionRecord outRecord, Ray rayIn)
{
if (node.IsLeaf)
{
outRecord.T = float.PositiveInfinity;
IntersectionRecord tempRec = new IntersectionRecord();
for (int i = node.surfaceIndexStart; i < node.surfaceIndexEnd; i++)
{
if (tris[i].Intersect(ref tempRec, rayIn))
{
// check if current t value is smaller
if (tempRec.T < outRecord.T)
{
outRecord = tempRec;
}
}
}
return(!float.IsPositiveInfinity(outRecord.T));
}
else
{
float t1 = node.lChild.IntersectTime(rayIn);
float t2 = node.rChild.IntersectTime(rayIn);
if (float.IsNaN(t1))
{
if (float.IsNaN(t2))
{
return(false);
}
return(IntersectHelper(node.rChild, ref outRecord, rayIn));
}
if (float.IsNaN(t2))
{
return(IntersectHelper(node.lChild, ref outRecord, rayIn));
}
// Need To Check Both
IntersectionRecord lRec = new IntersectionRecord();
IntersectionRecord rRec = new IntersectionRecord();
bool lHit, rHit;
lHit = IntersectHelper(node.lChild, ref lRec, rayIn);
rHit = IntersectHelper(node.rChild, ref rRec, rayIn);
if (lHit && rHit)
{
outRecord = lRec.T <= rRec.T ? lRec : rRec;
}
else if (lHit)
{
outRecord = lRec;
}
else if (rHit)
{
outRecord = rRec;
}
else
{
return(false);
}
return(true);
}
}
