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209 lines
8.5 KiB
209 lines
8.5 KiB
/*=========================================================================
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Program: Visualization Toolkit
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Module: $RCSfile: vtkOBBTree.h,v $
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Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
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All rights reserved.
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See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
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This software is distributed WITHOUT ANY WARRANTY; without even
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the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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PURPOSE. See the above copyright notice for more information.
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=========================================================================*/
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// .NAME vtkOBBTree - generate oriented bounding box (OBB) tree
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// .SECTION Description
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// vtkOBBTree is an object to generate oriented bounding box (OBB) trees.
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// An oriented bounding box is a bounding box that does not necessarily line
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// up along coordinate axes. The OBB tree is a hierarchical tree structure
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// of such boxes, where deeper levels of OBB confine smaller regions of space.
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//
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// To build the OBB, a recursive, top-down process is used. First, the root OBB
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// is constructed by finding the mean and covariance matrix of the cells (and
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// their points) that define the dataset. The eigenvectors of the covariance
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// matrix are extracted, giving a set of three orthogonal vectors that define
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// the tightest-fitting OBB. To create the two children OBB's, a split plane
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// is found that (approximately) divides the number cells in half. These are
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// then assigned to the children OBB's. This process then continues until
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// the MaxLevel ivar limits the recursion, or no split plane can be found.
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//
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// A good reference for OBB-trees is Gottschalk & Manocha in Proceedings of
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// Siggraph `96.
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// .SECTION Caveats
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// Since this algorithms works from a list of cells, the OBB tree will only
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// bound the "geometry" attached to the cells if the convex hull of the
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// cells bounds the geometry.
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//
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// Long, skinny cells (i.e., cells with poor aspect ratio) may cause
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// unsatisfactory results. This is due to the fact that this is a top-down
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// implementation of the OBB tree, requiring that one or more complete cells
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// are contained in each OBB. This requirement makes it hard to find good
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// split planes during the recursion process. A bottom-up implementation would
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// go a long way to correcting this problem.
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// .SECTION See Also
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// vtkLocator vtkCellLocator vtkPointLocator
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#ifndef __vtkOBBTree_h
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#define __vtkOBBTree_h
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#include "vtkCellLocator.h"
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class vtkMatrix4x4;
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// Special class defines node for the OBB tree
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//
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//BTX
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//
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class vtkOBBNode { //;prevent man page generation
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public:
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vtkOBBNode();
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~vtkOBBNode();
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double Corner[3]; //center point of this node
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double Axes[3][3]; //the axes defining the OBB - ordered from long->short
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vtkOBBNode *Parent; //parent node; NULL if root
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vtkOBBNode **Kids; //two children of this node; NULL if leaf
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vtkIdList *Cells; //list of cells in node
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void DebugPrintTree( int level, double *leaf_vol, int *minCells,
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int *maxCells );
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};
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//ETX
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//
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class VTK_GRAPHICS_EXPORT vtkOBBTree : public vtkCellLocator
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{
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public:
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vtkTypeRevisionMacro(vtkOBBTree,vtkCellLocator);
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void PrintSelf(ostream& os, vtkIndent indent);
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// Description:
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// Construct with automatic computation of divisions, averaging
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// 25 cells per octant.
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static vtkOBBTree *New();
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// Description:
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// Compute an OBB from the list of points given. Return the corner point
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// and the three axes defining the orientation of the OBB. Also return
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// a sorted list of relative "sizes" of axes for comparison purposes.
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void ComputeOBB(vtkPoints *pts, double corner[3], double max[3],
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double mid[3], double min[3], double size[3]);
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// Description:
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// Compute an OBB for the input dataset using the cells in the data.
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// Return the corner point and the three axes defining the orientation
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// of the OBB. Also return a sorted list of relative "sizes" of axes for
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// comparison purposes.
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void ComputeOBB(vtkDataSet *input, double corner[3], double max[3],
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double mid[3], double min[3], double size[3]);
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// Description:
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// Determine whether a point is inside or outside the data used to build
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// this OBB tree. The data must be a closed surface vtkPolyData data set.
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// The return value is +1 if outside, -1 if inside, and 0 if undecided.
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int InsideOrOutside(const double point[3]);
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// Description:
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// Take the passed line segment and intersect it with the data set.
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// This method assumes that the data set is a vtkPolyData that describes
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// a closed surface, and the intersection points that are returned in
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// 'points' alternate between entrance points and exit points.
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// The return value of the function is 0 if no intersections were found,
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// -1 if point 'a0' lies inside the closed surface, or +1 if point 'a0'
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// lies outside the closed surface.
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// Either 'points' or 'cellIds' can be set to NULL if you don't want
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// to receive that information.
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int IntersectWithLine(const double a0[3], const double a1[3],
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vtkPoints *points, vtkIdList *cellIds);
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// Description:
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// Return the first intersection of the specified line segment with
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// the OBB tree, as well as information about the cell which the
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// line segment intersected.
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int IntersectWithLine(double a0[3], double a1[3], double tol,
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double& t, double x[3], double pcoords[3],
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int &subId);
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int IntersectWithLine(double a0[3], double a1[3], double tol,
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double& t, double x[3], double pcoords[3],
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int &subId, vtkIdType &cellId);
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int IntersectWithLine(double a0[3], double a1[3], double tol,
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double& t, double x[3], double pcoords[3],
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int &subId, vtkIdType &cellId, vtkGenericCell *cell);
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//BTX
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// Description:
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// Returns true if nodeB and nodeA are disjoint after optional
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// transformation of nodeB with matrix XformBtoA
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int DisjointOBBNodes( vtkOBBNode *nodeA, vtkOBBNode *nodeB,
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vtkMatrix4x4 *XformBtoA );
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// Description:
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// Returns true if line intersects node.
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int LineIntersectsNode( vtkOBBNode *pA, double b0[3], double b1[3] );
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// Description:
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// Returns true if triangle (optionally transformed) intersects node.
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int TriangleIntersectsNode( vtkOBBNode *pA,
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double p0[3], double p1[3],
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double p2[3], vtkMatrix4x4 *XformBtoA );
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// Description:
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// For each intersecting leaf node pair, call function.
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// OBBTreeB is optionally transformed by XformBtoA before testing.
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int IntersectWithOBBTree( vtkOBBTree *OBBTreeB, vtkMatrix4x4 *XformBtoA,
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int(*function)( vtkOBBNode *nodeA,
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vtkOBBNode *nodeB,
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vtkMatrix4x4 *Xform,
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void *arg ),
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void *data_arg );
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//ETX
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// Description:
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// Satisfy locator's abstract interface, see vtkLocator.
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void FreeSearchStructure();
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void BuildLocator();
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// Description:
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// Create polygonal representation for OBB tree at specified level. If
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// level < 0, then the leaf OBB nodes will be gathered. The aspect ratio (ar)
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// and line diameter (d) are used to control the building of the
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// representation. If a OBB node edge ratio's are greater than ar, then the
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// dimension of the OBB is collapsed (OBB->plane->line). A "line" OBB will be
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// represented either as two crossed polygons, or as a line, depending on
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// the relative diameter of the OBB compared to the diameter (d).
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void GenerateRepresentation(int level, vtkPolyData *pd);
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//BTX
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protected:
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vtkOBBTree();
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~vtkOBBTree();
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// Compute an OBB from the list of cells given. This used to be
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// public but should not have been. A public call has been added
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// so that the functionality can be accessed.
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void ComputeOBB(vtkIdList *cells, double corner[3], double max[3],
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double mid[3], double min[3], double size[3]);
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vtkOBBNode *Tree;
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void BuildTree(vtkIdList *cells, vtkOBBNode *parent, int level);
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vtkPoints *PointsList;
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int *InsertedPoints;
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int OBBCount;
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int DeepestLevel;
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void DeleteTree(vtkOBBNode *OBBptr);
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void GeneratePolygons(vtkOBBNode *OBBptr, int level, int repLevel,
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vtkPoints* pts, vtkCellArray *polys);
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//ETX
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private:
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vtkOBBTree(const vtkOBBTree&); // Not implemented.
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void operator=(const vtkOBBTree&); // Not implemented.
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};
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#endif
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