internal BVHNode(BVH <T> bvh)
{
GObjects = new List <T>();
Left = Right = null;
Parent = null;
this.NodeNumber = bvh.nodeCount++;
}
private BVHNode(BVH <T> bvh, BVHNode <T> lparent, List <T> gobjectlist, Axis lastSplitAxis, int curdepth)
{
IBVHNodeAdapter <T> nAda = bvh.nAda;
this.NodeNumber = bvh.nodeCount++;
this.Parent = lparent; // save off the parent BVHGObj Node
this.Depth = curdepth;
if (bvh.maxDepth < curdepth)
{
bvh.maxDepth = curdepth;
}
// Early out check due to bad data
// If the list is empty then we have no BVHGObj, or invalid parameters are passed in
if (gobjectlist == null || gobjectlist.Count < 1)
{
throw new Exception("ssBVHNode constructed with invalid paramaters");
}
// Check if we’re at our LEAF node, and if so, save the objects and stop recursing. Also store the min/max for the leaf node and update the parent appropriately
if (gobjectlist.Count <= bvh.LEAF_OBJ_MAX)
{
// once we reach the leaf node, we must set prev/next to null to signify the end
Left = null;
Right = null;
// at the leaf node we store the remaining objects, so initialize a list
GObjects = gobjectlist;
GObjects.ForEach(o => nAda.MapObjectToBVHLeaf(o, this));
ComputeVolume(nAda);
SplitIfNecessary(nAda);
}
else
{
// --------------------------------------------------------------------------------------------
// if we have more than (bvh.LEAF_OBJECT_COUNT) objects, then compute the volume and split
GObjects = gobjectlist;
ComputeVolume(nAda);
SplitNode(nAda);
ChildRefit(nAda, propagate: false);
}
}
internal BVHNode(BVH <T> bvh, List <T> gobjectlist) : this(bvh, null, gobjectlist, Axis.X, 0)
{
}
/// <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;
}
}
}
