Open CASCADE Technology 7.9.0
 
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BVH_BaseTraverse< MetricType > Class Template Reference

The classes implement the traverse of the BVH tree. More...

#include <BVH_Traverse.hxx>

Public Member Functions

Metrics comparison for choosing the best branch

Compares the two metrics and chooses the best one. Returns true if the first metric is better than the second, false otherwise.

virtual Standard_Boolean IsMetricBetter (const MetricType &, const MetricType &) const
 
Rejection of the node by metric

Rejects the node by the metric

virtual Standard_Boolean RejectMetric (const MetricType &) const
 
Condition to stop the descend

Returns the flag controlling the tree descend. Returns true if the tree descend should be stopped.

virtual Standard_Boolean Stop () const
 

Protected Member Functions

Constructors

Constructor

 BVH_BaseTraverse ()
 Destructor.
 
virtual ~BVH_BaseTraverse ()
 Destructor.
 

Detailed Description

template<class MetricType>
class BVH_BaseTraverse< MetricType >

The classes implement the traverse of the BVH tree.

There are two traverse methods implemented:

  • Traverse of the single tree
  • Parallel traverse of two trees

To perform Selection of the elements from BVH_Tree using the traverse methods implemented here it is required to define Acceptance/Rejection rules in the following methods:

  • RejectNode - Node rejection by its bounding box. It is applied to both inner and outer nodes of the BVH tree. Optionally, the method should compute the metric for the node which will allow performing traverse faster by descending by the best branches.
  • Accept - Element acceptance. It takes the index of the element of BVH tree. The access to the element itself should be performed through the set on which BVH is built. The Accept method implements the leaf node operation and usually defines the logic of the whole operation.
  • IsMetricBetter - Compares the metrics of the nodes and returns true if the left metric is better than the right one.
  • RejectMetric - Node rejection by the metric. It should compare the metric of the node with the global one and return true if the global metric is better than the given one.
  • Stop - implements conditions to stop the tree descend if the necessary elements are already found.

The selector of a single tree has an extra method which allows accepting the whole branches without any further checks (e.g. full inclusion test):

  • AcceptMetric - basing on the metric of the node decides if the node may be accepted without any further checks.

Two ways of selection are possible:

  1. Set the BVH set containing the tree and use the method Select() which allows using common interface for setting the BVH Set for accessing the BVH tree and elements in the Accept method.
  2. Keep the BVHSetType void, do not set the BVH set and use the method Select (const BVH_Tree<>&) which allows performing selection on the arbitrary BVH tree.

Here is the example of usage of the traverse to find the point-triangulation minimal distance.

// Structure to contain points of the triangle
struct Triangle
{
Triangle() {}
Triangle(const BVH_Vec3d& theNode1,
const BVH_Vec3d& theNode2,
const BVH_Vec3d& theNode3)
: Node1 (theNode1), Node2 (theNode2), Node3 (theNode3)
{}
BVH_Vec3d Node1;
BVH_Vec3d Node2;
BVH_Vec3d Node3;
};
// Selector for min point-triangulation distance
class BVH_PointTriangulationSqDist :
public BVH_Distance<Standard_Real, 3, BVH_Vec3d, BVH_BoxSet<Standard_Real, 3, Triangle>>
{
public:
// Computes the distance from the point to bounding box
virtual Standard_Boolean RejectNode (const BVH_Vec3d& theCMin,
const BVH_Vec3d& theCMax,
Standard_Real& theDistance) const Standard_OVERRIDE
{
theCMax); return RejectMetric (theDistance);
}
// Computes the distance from the point to triangle
virtual Standard_Boolean Accept (const Standard_Integer theIndex,
{
const Triangle& aTri = myBVHSet->Element (theIndex);
aTri.Node1, aTri.Node2, aTri.Node3); if (aDist < myDistance)
{
myDistance = aDist;
return Standard_True;
}
}
};
// Point to which the distance is required
BVH_Vec3d aPoint = ...;
// BVH Set containing triangulation
opencascade::handle<BVH_BoxSet<Standard_Real, 3, Triangle>> aTriangulationSet = ...;
BVH_PointTriangulationSqDist aDistTool;
aDistTool.SetObject (aPoint);
aDistTool.SetBVHSet (aTriangulationSet.get());
aDistTool.ComputeDistance();
if (aDistTool.IsDone())
{
Standard_Real aPointTriSqDist = aDistTool.Distance();
}
BVH::VectorType< Standard_Real, 3 >::Type BVH_Vec3d
3D vector of double precision reals.
Definition BVH_Types.hxx:158
#define Standard_OVERRIDE
Should be used in declarations of virtual methods overridden in the derived classes,...
Definition Standard_Macro.hxx:41
bool Standard_Boolean
Definition Standard_TypeDef.hxx:64
#define Standard_False
Definition Standard_TypeDef.hxx:56
int Standard_Integer
Definition Standard_TypeDef.hxx:61
#define Standard_True
Definition Standard_TypeDef.hxx:57
double Standard_Real
Definition Standard_TypeDef.hxx:63
virtual Standard_Boolean RejectMetric(const NumType &theMetric) const override
Rejects the branch by the metric.
Definition BVH_Distance.hxx:71
NumType myDistance
Distance.
Definition BVH_Distance.hxx:83
ObjectType myObject
Object to compute the distance to.
Definition BVH_Distance.hxx:85
static T PointTriangleSquareDistance(const BVH_VecNt &thePoint, const BVH_VecNt &theNode0, const BVH_VecNt &theNode1, const BVH_VecNt &theNode2)
Computes square distance between point and triangle.
Definition BVH_Tools.hxx:248
static T PointBoxSquareDistance(const BVH_VecNt &thePoint, const BVH_Box< T, N > &theBox)
Computes square distance between point and bounding box.
Definition BVH_Tools.hxx:81
virtual Standard_Boolean RejectNode(const BVH_VecNt &theCornerMin, const BVH_VecNt &theCornerMax, NumType &theMetric) const=0
virtual Standard_Boolean Accept(const Standard_Integer theIndex, const NumType &theMetric)=0
BVHSetType * myBVHSet
Definition BVH_Traverse.hxx:242

Abstract class implementing the base Traverse interface required for selection of the elements from BVH tree.

Template Parameters
MetricTypeType of metric to perform more optimal tree descend

Constructor & Destructor Documentation

◆ BVH_BaseTraverse()

template<class MetricType>
BVH_BaseTraverse< MetricType >::BVH_BaseTraverse ( )
inlineprotected

Destructor.

◆ ~BVH_BaseTraverse()

template<class MetricType>
virtual BVH_BaseTraverse< MetricType >::~BVH_BaseTraverse ( )
inlineprotectedvirtual

Destructor.

Member Function Documentation

◆ IsMetricBetter()

template<class MetricType>
virtual Standard_Boolean BVH_BaseTraverse< MetricType >::IsMetricBetter ( const MetricType & ,
const MetricType &  ) const
inlinevirtual

◆ RejectMetric()

◆ Stop()


The documentation for this class was generated from the following file: