// This method will recompute the Bound without precondition. It will not cascade upwards to parent nodes, because
// it is intended to be called recursively.
public void BottomUpRecalculateBound()
{
List <BoundingBox> childBounds = new List <BoundingBox>();
foreach (SceneNode child in mChildren)
{
ImplicitBoundingBoxNode implicitBVChild = child as ImplicitBoundingBoxNode;
if (implicitBVChild != null)
{
implicitBVChild.BottomUpRecalculateBound();
childBounds.Add(implicitBVChild.Bound);
}
else
{
childBounds.AddRange(child.FindExplicitBoundingVolumes());
}
}
BoundingBox combinedBound = childBounds.First();
foreach (BoundingBox childBox in childBounds.Skip(1))
{
combinedBound = BoundingBox.CreateMerged(combinedBound, childBox);
}
Bound = combinedBound;
}
public void InsertNode(SceneNode node, PartitionCategories category)
{
switch (category)
{
case PartitionCategories.Dynamic:
mDynamicRoot.AddChild(node);
break;
case PartitionCategories.Static:
ImplicitBoundingBoxNode boxNode = node as ImplicitBoundingBoxNode;
if (boxNode == null)
{
boxNode = new ImplicitBoundingBoxNode(true);
boxNode.AddChild(node);
boxNode.RecalculateBound();
}
if (mStaticTreeRoot == null)
{
mStaticTreeRoot = boxNode;
}
else
{
mStaticTreeRoot.InsertNodeIntoBVH(boxNode);
}
break;
case PartitionCategories.Skybox:
mSkyboxRoot.AddChild(node);
break;
}
}
public void InsertNodeIntoBVH(ImplicitBoundingBoxNode aabb)
{
// See http://tog.acm.org/resources/RTNews/html/rtnews3a.html#art6 for algorithm details.
BVHInsertion bestInsertion = FindBestLocalInsertion(aabb, 0.0f);
BVHInsertion bestDeepInsertion = FindBestDeepInsertion(aabb, bestInsertion.LocationInheritance, bestInsertion.Cost);
if (bestDeepInsertion.Cost < bestInsertion.Cost)
bestInsertion = bestDeepInsertion;
// Perform insertion.
switch (bestInsertion.Method)
{
case BVHInsertion.InsertionMethod.AsSibling:
ImplicitBoundingBoxNode copyOfLocation = new ImplicitBoundingBoxNode(bestInsertion.Location);
bestInsertion.Location.IsLeaf = false;
bestInsertion.Location.mChildren = new List<SceneNode>();
bestInsertion.Location.AddChild(copyOfLocation);
bestInsertion.Location.AddChild(aabb);
break;
case BVHInsertion.InsertionMethod.AsChild:
bestInsertion.Location.AddChild(aabb);
break;
}
// The Bound must be recomputed after this operation.
bestInsertion.Location.RecalculateBound();
}
private BVHInsertion FindBestLocalInsertion(ImplicitBoundingBoxNode aabb, float inheritedCost)
{
float newArea = GetAABBArea(BoundingBox.CreateMerged(Bound, aabb.Bound));
float asSiblingCost = 2.0f * newArea;
float areaDiff = newArea - GetAABBArea(Bound);
if (IsLeaf)
{
BVHInsertion leafInsertion = new BVHInsertion(this, BVHInsertion.InsertionMethod.AsSibling);
leafInsertion.Cost = asSiblingCost + inheritedCost;
leafInsertion.LocationInheritance = inheritedCost;
return(leafInsertion);
}
float asChildCost = mChildren.Count * areaDiff + newArea;
BVHInsertion bestInsertion;
if (asSiblingCost < asChildCost)
{
bestInsertion = new BVHInsertion(this, BVHInsertion.InsertionMethod.AsSibling);
bestInsertion.Cost = asSiblingCost + inheritedCost;
}
else
{
bestInsertion = new BVHInsertion(this, BVHInsertion.InsertionMethod.AsChild);
bestInsertion.Cost = asChildCost + inheritedCost;
}
bestInsertion.LocationInheritance = mChildren.Count * areaDiff + inheritedCost;
return(bestInsertion);
}
public void InsertNodeIntoBVH(ImplicitBoundingBoxNode aabb)
{
// See http://tog.acm.org/resources/RTNews/html/rtnews3a.html#art6 for algorithm details.
BVHInsertion bestInsertion = FindBestLocalInsertion(aabb, 0.0f);
BVHInsertion bestDeepInsertion = FindBestDeepInsertion(aabb, bestInsertion.LocationInheritance, bestInsertion.Cost);
if (bestDeepInsertion.Cost < bestInsertion.Cost)
{
bestInsertion = bestDeepInsertion;
}
// Perform insertion.
switch (bestInsertion.Method)
{
case BVHInsertion.InsertionMethod.AsSibling:
ImplicitBoundingBoxNode copyOfLocation = new ImplicitBoundingBoxNode(bestInsertion.Location);
bestInsertion.Location.IsLeaf = false;
bestInsertion.Location.mChildren = new List <SceneNode>();
bestInsertion.Location.AddChild(copyOfLocation);
bestInsertion.Location.AddChild(aabb);
break;
case BVHInsertion.InsertionMethod.AsChild:
bestInsertion.Location.AddChild(aabb);
break;
}
// The Bound must be recomputed after this operation.
bestInsertion.Location.RecalculateBound();
}
public SceneGraphRoot(SceneResources sceneResources)
{
mRenderContext = new RenderContext(sceneResources);
mDynamicRoot = new SceneNode();
mStaticTreeRoot = null;
mSkyboxRoot = new SceneNode();
mTraversalData = new TraversalContext();
}
public SceneGraphRoot(SceneResources sceneResources)
{
mRenderContext = new RenderContext(sceneResources);
mDynamicRoot = new SceneNode();
mStaticTreeRoot = null;
mSkyboxRoot = new SceneNode();
mTraversalData = new TraversalContext();
}
public void SetBoundCascading(BoundingBox newBound)
{
if (newBound != Bound)
{
Bound = newBound;
ImplicitBoundingBoxNode parentBox = mParent as ImplicitBoundingBoxNode;
if (parentBox != null)
{
parentBox.RecalculateBound();
}
}
}
protected override void ActorInitializedHandler(object sender, EventArgs e)
{
ImplicitBoundingBoxNode implicitBox = SceneGraph as ImplicitBoundingBoxNode;
if (implicitBox != null)
{
implicitBox.BottomUpRecalculateBound();
}
// We shouldn't need this data anymore.
Heights = null;
base.ActorInitializedHandler(sender, e);
}
private SceneNode PartitionSectorGrid(int xMinIndex, int xCount, int zMinIndex, int zCount)
{
if (xCount == 1 && zCount == 1)
{
return(CreateSectorNode(xMinIndex, zMinIndex));
}
SceneNode child1 = null;
SceneNode child2 = null;
if (xCount > zCount)
{
child1 = PartitionSectorGrid(
xMinIndex,
xCount / 2,
zMinIndex,
zCount);
child2 = PartitionSectorGrid(
xMinIndex + xCount / 2,
xCount - xCount / 2,
zMinIndex,
zCount);
}
else
{
child1 = PartitionSectorGrid(
xMinIndex,
xCount,
zMinIndex,
zCount / 2);
child2 = PartitionSectorGrid(
xMinIndex,
xCount,
zMinIndex + zCount / 2,
zCount - zCount / 2);
}
ImplicitBoundingBoxNode implicitChild1 = child1 as ImplicitBoundingBoxNode;
ImplicitBoundingBoxNode implicitChild2 = child2 as ImplicitBoundingBoxNode;
// If either child is not an implicit node, then this node must be marked as a 'leaf' node so the BVH insertion will work correctly.
ImplicitBoundingBoxNode parentPartition = new ImplicitBoundingBoxNode(implicitChild1 == null || implicitChild2 == null);
parentPartition.AddChild(child1);
parentPartition.AddChild(child2);
return(parentPartition);
}
private BVHInsertion FindBestDeepInsertion(ImplicitBoundingBoxNode aabb, float inheritance, float costToBeat)
{
if (IsLeaf)
{
return(BVHInsertion.WorstInsertion);
}
// Find best local insertion cost for each child:
BVHInsertion bestChildInsertion = BVHInsertion.WorstInsertion;
foreach (ImplicitBoundingBoxNode child in mChildren.OfType <ImplicitBoundingBoxNode>())
{
BVHInsertion altChildInsertion = child.FindBestLocalInsertion(aabb, inheritance);
if (altChildInsertion.Cost < bestChildInsertion.Cost)
{
bestChildInsertion = altChildInsertion;
}
}
// Which child had the best local cost? Was it better than our local cost? If so, update the costToBeat.
if (bestChildInsertion.Cost < costToBeat)
{
costToBeat = bestChildInsertion.Cost;
}
// Finally, explore the deeper insertion costs of that child...
// Make sure the child's inheritance permits improvement before recursing.
if (bestChildInsertion.LocationInheritance < costToBeat)
{
BVHInsertion bestChildDeepInsertion = bestChildInsertion.Location.FindBestDeepInsertion(aabb, bestChildInsertion.LocationInheritance, costToBeat);
// Compare the deep insertion cost with our best so far...
if (bestChildDeepInsertion.Cost < bestChildInsertion.Cost)
{
return(bestChildDeepInsertion);
}
}
return(bestChildInsertion);
}
public BVHInsertion(ImplicitBoundingBoxNode location, InsertionMethod method)
{
Location = location;
Method = method;
}
public ImplicitBoundingBoxNode(ImplicitBoundingBoxNode orig)
: base(orig)
{
Bound = orig.Bound;
IsLeaf = orig.IsLeaf;
}
private BVHInsertion FindBestLocalInsertion(ImplicitBoundingBoxNode aabb, float inheritedCost)
{
float newArea = GetAABBArea(BoundingBox.CreateMerged(Bound, aabb.Bound));
float asSiblingCost = 2.0f * newArea;
float areaDiff = newArea - GetAABBArea(Bound);
if (IsLeaf)
{
BVHInsertion leafInsertion = new BVHInsertion(this, BVHInsertion.InsertionMethod.AsSibling);
leafInsertion.Cost = asSiblingCost + inheritedCost;
leafInsertion.LocationInheritance = inheritedCost;
return leafInsertion;
}
float asChildCost = mChildren.Count * areaDiff + newArea;
BVHInsertion bestInsertion;
if (asSiblingCost < asChildCost)
{
bestInsertion = new BVHInsertion(this, BVHInsertion.InsertionMethod.AsSibling);
bestInsertion.Cost = asSiblingCost + inheritedCost;
}
else
{
bestInsertion = new BVHInsertion(this, BVHInsertion.InsertionMethod.AsChild);
bestInsertion.Cost = asChildCost + inheritedCost;
}
bestInsertion.LocationInheritance = mChildren.Count * areaDiff + inheritedCost;
return bestInsertion;
}
private BVHInsertion FindBestDeepInsertion(ImplicitBoundingBoxNode aabb, float inheritance, float costToBeat)
{
if (IsLeaf)
return BVHInsertion.WorstInsertion;
// Find best local insertion cost for each child:
BVHInsertion bestChildInsertion = BVHInsertion.WorstInsertion;
foreach (ImplicitBoundingBoxNode child in mChildren.OfType<ImplicitBoundingBoxNode>())
{
BVHInsertion altChildInsertion = child.FindBestLocalInsertion(aabb, inheritance);
if (altChildInsertion.Cost < bestChildInsertion.Cost)
bestChildInsertion = altChildInsertion;
}
// Which child had the best local cost? Was it better than our local cost? If so, update the costToBeat.
if (bestChildInsertion.Cost < costToBeat)
costToBeat = bestChildInsertion.Cost;
// Finally, explore the deeper insertion costs of that child...
// Make sure the child's inheritance permits improvement before recursing.
if (bestChildInsertion.LocationInheritance < costToBeat)
{
BVHInsertion bestChildDeepInsertion = bestChildInsertion.Location.FindBestDeepInsertion(aabb, bestChildInsertion.LocationInheritance, costToBeat);
// Compare the deep insertion cost with our best so far...
if (bestChildDeepInsertion.Cost < bestChildInsertion.Cost)
return bestChildDeepInsertion;
}
return bestChildInsertion;
}
public ImplicitBoundingBoxNode(ImplicitBoundingBoxNode orig)
: base(orig)
{
Bound = orig.Bound;
IsLeaf = orig.IsLeaf;
}
public BVHInsertion(ImplicitBoundingBoxNode location, InsertionMethod method)
{
Location = location;
Method = method;
}
private SceneNode PartitionSectorGrid(int xMinIndex, int xCount, int zMinIndex, int zCount)
{
if (xCount == 1 && zCount == 1)
return CreateSectorNode(xMinIndex, zMinIndex);
SceneNode child1 = null;
SceneNode child2 = null;
if (xCount > zCount)
{
child1 = PartitionSectorGrid(
xMinIndex,
xCount / 2,
zMinIndex,
zCount);
child2 = PartitionSectorGrid(
xMinIndex + xCount / 2,
xCount - xCount / 2,
zMinIndex,
zCount);
}
else
{
child1 = PartitionSectorGrid(
xMinIndex,
xCount,
zMinIndex,
zCount / 2);
child2 = PartitionSectorGrid(
xMinIndex,
xCount,
zMinIndex + zCount / 2,
zCount - zCount / 2);
}
ImplicitBoundingBoxNode implicitChild1 = child1 as ImplicitBoundingBoxNode;
ImplicitBoundingBoxNode implicitChild2 = child2 as ImplicitBoundingBoxNode;
// If either child is not an implicit node, then this node must be marked as a 'leaf' node so the BVH insertion will work correctly.
ImplicitBoundingBoxNode parentPartition = new ImplicitBoundingBoxNode(implicitChild1 == null || implicitChild2 == null);
parentPartition.AddChild(child1);
parentPartition.AddChild(child2);
return parentPartition;
}
public void InsertNode(SceneNode node, PartitionCategories category)
{
switch (category)
{
case PartitionCategories.Dynamic:
mDynamicRoot.AddChild(node);
break;
case PartitionCategories.Static:
ImplicitBoundingBoxNode boxNode = node as ImplicitBoundingBoxNode;
if (boxNode == null)
{
boxNode = new ImplicitBoundingBoxNode(true);
boxNode.AddChild(node);
boxNode.RecalculateBound();
}
if (mStaticTreeRoot == null)
{
mStaticTreeRoot = boxNode;
}
else
{
mStaticTreeRoot.InsertNodeIntoBVH(boxNode);
}
break;
case PartitionCategories.Skybox:
mSkyboxRoot.AddChild(node);
break;
}
}
