Skip to content


Subversion checkout URL

You can clone with
Download ZIP
branch: master
Fetching contributors…

Cannot retrieve contributors at this time

150 lines (122 sloc) 5.635 kB
Program: Visualization Toolkit
Module: vtkLocator.h
Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
All rights reserved.
See Copyright.txt or for details.
This software is distributed WITHOUT ANY WARRANTY; without even
PURPOSE. See the above copyright notice for more information.
// .NAME vtkLocator - abstract base class for objects that accelerate spatial searches
// .SECTION Description
// vtkLocator is an abstract base class for spatial search objects, or
// locators. The principle behind locators is that they divide 3-space into
// small pieces (or "buckets") that can be quickly found in response to
// queries like point location, line intersection, or object-object
// intersection.
// The purpose of this base class is to provide ivars and methods shared by
// all locators. The GenerateRepresentation() is one such interesting method.
// This method works in conjunction with vtkLocatorFilter to create polygonal
// representations for the locator. For example, if the locator is an OBB tree
// (i.e., vtkOBBTree.h), then the representation is a set of one or more
// oriented bounding boxes, depending upon the specified level.
// Locators typically work as follows. One or more "entities", such as
// points or cells, are inserted into the tree. These entities are associated
// with one or more buckets. Then, when performing geometric operations, the
// operations are performed first on the buckets, and then if the operation
// tests positive, then on the entities in the bucket. For example, during
// collision tests, the locators are collided first to identify intersecting
// buckets. If an intersection is found, more expensive operations are then
// carried out on the entities in the bucket.
// To obtain good performance, locators are often organized in a tree
// structure. In such a structure, there are frequently multiple "levels"
// corresponding to different nodes in the tree. So the word level (in the
// context of the locator) can be used to specify a particular representation
// in the tree. For example, in an octree (which is a tree with 8 children),
// level 0 is the bounding box, or root octant, and level 1 consists of its
// eight children.
// .SECTION See Also
// vtkPointLocator vtkCellLocator vtkOBBTree vtkMergePoints
#ifndef __vtkLocator_h
#define __vtkLocator_h
#include "vtkObject.h"
class vtkDataSet;
class vtkPolyData;
class VTK_FILTERING_EXPORT vtkLocator : public vtkObject
void PrintSelf(ostream& os, vtkIndent indent);
// Description:
// Build the locator from the points/cells defining this dataset.
virtual void SetDataSet(vtkDataSet*);
// Description:
// Set the maximum allowable level for the tree. If the Automatic ivar is
// off, this will be the target depth of the locator.
// Initial value is 8.
// Description:
// Get the level of the locator (determined automatically if Automatic is
// true). The value of this ivar may change each time the locator is built.
// Initial value is 8.
// Description:
// Boolean controls whether locator depth/resolution of locator is computed
// automatically from average number of entities in bucket. If not set,
// there will be an explicit method to control the construction of the
// locator (found in the subclass).
// Description:
// Specify absolute tolerance (in world coordinates) for performing
// geometric operations.
// Description:
// Cause the locator to rebuild itself if it or its input dataset has
// changed.
virtual void Update();
// Description:
// Initialize locator. Frees memory and resets object as appropriate.
virtual void Initialize();
// Description:
// Build the locator from the input dataset.
virtual void BuildLocator() = 0;
// Description:
// Free the memory required for the spatial data structure.
virtual void FreeSearchStructure() = 0;
// Description:
// Method to build a representation at a particular level. Note that the
// method GetLevel() returns the maximum number of levels available for
// the tree. You must provide a vtkPolyData object into which to place the
// data.
virtual void GenerateRepresentation(int level, vtkPolyData *pd) = 0;
// Description:
// Return the time of the last data structure build.
vtkGetMacro(BuildTime, unsigned long);
// Description:
// Handle the PointSet <-> Locator loop.
virtual void Register(vtkObjectBase *o);
virtual void UnRegister(vtkObjectBase *o);
vtkDataSet *DataSet;
int Automatic; // boolean controls automatic subdivision (or uses user spec.)
double Tolerance; // for performing merging
int MaxLevel;
int Level;
vtkTimeStamp BuildTime; // time at which locator was built
virtual void ReportReferences(vtkGarbageCollector*);
vtkLocator(const vtkLocator&); // Not implemented.
void operator=(const vtkLocator&); // Not implemented.
Jump to Line
Something went wrong with that request. Please try again.