internal static void AddObjectPushdown(IBVHNodeAdapter <T> nAda, BVHNode <T> curNode, T newOb)
{
var left = curNode.Left;
var right = curNode.Right;
// merge and pushdown left and right as a new node..
var mergedSubnode = new BVHNode <T>(nAda.BVH);
mergedSubnode.Left = left;
mergedSubnode.Right = right;
mergedSubnode.Parent = curNode;
mergedSubnode.GObjects = null; // we need to be an interior node... so null out our object list..
left.Parent = mergedSubnode;
right.Parent = mergedSubnode;
mergedSubnode.ChildRefit(nAda, propagate: false);
// make new subnode for obj
var newSubnode = new BVHNode <T>(nAda.BVH);
newSubnode.Parent = curNode;
newSubnode.GObjects = new List <T> {
newOb
};
nAda.MapObjectToBVHLeaf(newOb, newSubnode);
newSubnode.ComputeVolume(nAda);
// make assignments..
curNode.Left = mergedSubnode;
curNode.Right = newSubnode;
curNode.SetDepth(nAda, curNode.Depth); // propagate new depths to our children.
curNode.ChildRefit(nAda);
}
internal bool RefitVolume(IBVHNodeAdapter <T> nAda)
{
if (GObjects.Count == 0)
{
// TODO: fix this... we should never get called in this case...
throw new NotImplementedException();
}
Bounds oldbox = Box;
ComputeVolume(nAda);
if (!Box.Equals(oldbox))
{
if (Parent != null)
{
Parent.ChildRefit(nAda);
}
return(true);
}
else
{
return(false);
}
}
/// <summary>
/// tryRotate looks at all candidate rotations, and executes the rotation with the best resulting SAH (if any)
/// </summary>
/// <param name="bvh"></param>
internal void TryRotate(BVH <T> bvh)
{
IBVHNodeAdapter <T> nAda = bvh.nAda;
// if we are not a grandparent, then we can't rotate, so queue our parent and bail out
if (Left.IsLeaf && Right.IsLeaf)
{
if (Parent != null)
{
bvh.refitNodes.Add(Parent);
return;
}
}
// for each rotation, check that there are grandchildren as necessary (aka not a leaf)
// then compute total SAH cost of our branches after the rotation.
float mySA = SA(Left) + SA(Right);
RotOpt bestRot = EachRot.Min((rot) =>
{
switch (rot)
{
case Rot.NONE: return(new RotOpt(mySA, Rot.NONE));
// child to grandchild rotations
case Rot.L_RL:
if (Right.IsLeaf)
{
return(new RotOpt(float.MaxValue, Rot.NONE));
}
else
{
return(new RotOpt(SA(Right.Left) + SA(AABBofPair(Left, Right.Right)), rot));
}
case Rot.L_RR:
if (Right.IsLeaf)
{
return(new RotOpt(float.MaxValue, Rot.NONE));
}
else
{
return(new RotOpt(SA(Right.Right) + SA(AABBofPair(Left, Right.Left)), rot));
}
case Rot.R_LL:
if (Left.IsLeaf)
{
return(new RotOpt(float.MaxValue, Rot.NONE));
}
else
{
return(new RotOpt(SA(AABBofPair(Right, Left.Right)) + SA(Left.Left), rot));
}
case Rot.R_LR:
if (Left.IsLeaf)
{
return(new RotOpt(float.MaxValue, Rot.NONE));
}
else
{
return(new RotOpt(SA(AABBofPair(Right, Left.Left)) + SA(Left.Right), rot));
}
// grandchild to grandchild rotations
case Rot.LL_RR:
if (Left.IsLeaf || Right.IsLeaf)
{
return(new RotOpt(float.MaxValue, Rot.NONE));
}
else
{
return(new RotOpt(SA(AABBofPair(Right.Right, Left.Right)) + SA(AABBofPair(Right.Left, Left.Left)), rot));
}
case Rot.LL_RL:
if (Left.IsLeaf || Right.IsLeaf)
{
return(new RotOpt(float.MaxValue, Rot.NONE));
}
else
{
return(new RotOpt(SA(AABBofPair(Right.Left, Left.Right)) + SA(AABBofPair(Left.Left, Right.Right)), rot));
}
// unknown...
default: throw new NotImplementedException("missing implementation for BVH Rotation SAH Computation .. " + rot.ToString());
}
});
// perform the best rotation...
if (bestRot.rot != Rot.NONE)
{
// if the best rotation is no-rotation... we check our parents anyhow..
if (Parent != null)
{
// but only do it some random percentage of the time.
if ((DateTime.Now.Ticks % 100) < 2)
{
bvh.refitNodes.Add(Parent);
}
}
}
else
{
if (Parent != null)
{
bvh.refitNodes.Add(Parent);
}
if (((mySA - bestRot.SAH) / mySA) < 0.3f)
{
return; // the benefit is not worth the cost
}
Console.WriteLine("BVH swap {0} from {1} to {2}", bestRot.rot.ToString(), mySA, bestRot.SAH);
// in order to swap we need to:
// 1. swap the node locations
// 2. update the depth (if child-to-grandchild)
// 3. update the parent pointers
// 4. refit the boundary box
BVHNode <T> swap = null;
switch (bestRot.rot)
{
case Rot.NONE: break;
// child to grandchild rotations
case Rot.L_RL: swap = Left; Left = Right.Left; Left.Parent = this; Right.Left = swap; swap.Parent = Right; Right.ChildRefit(nAda, propagate: false); break;
case Rot.L_RR: swap = Left; Left = Right.Right; Left.Parent = this; Right.Right = swap; swap.Parent = Right; Right.ChildRefit(nAda, propagate: false); break;
case Rot.R_LL: swap = Right; Right = Left.Left; Right.Parent = this; Left.Left = swap; swap.Parent = Left; Left.ChildRefit(nAda, propagate: false); break;
case Rot.R_LR: swap = Right; Right = Left.Right; Right.Parent = this; Left.Right = swap; swap.Parent = Left; Left.ChildRefit(nAda, propagate: false); break;
// grandchild to grandchild rotations
case Rot.LL_RR: swap = Left.Left; Left.Left = Right.Right; Right.Right = swap; Left.Left.Parent = Left; swap.Parent = Right; Left.ChildRefit(nAda, propagate: false); Right.ChildRefit(nAda, propagate: false); break;
case Rot.LL_RL: swap = Left.Left; Left.Left = Right.Left; Right.Left = swap; Left.Left.Parent = Left; swap.Parent = Right; Left.ChildRefit(nAda, propagate: false); Right.ChildRefit(nAda, propagate: false); break;
// unknown...
default: throw new NotImplementedException("missing implementation for BVH Rotation .. " + bestRot.rot.ToString());
}
// fix the depths if necessary....
switch (bestRot.rot)
{
case Rot.L_RL:
case Rot.L_RR:
case Rot.R_LL:
case Rot.R_LR:
this.SetDepth(nAda, this.Depth);
break;
}
}
}
