ObbTree.cpp

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    1 // simple example construct obb tree and ray-tracing the tree
    2 // it reads triangle mesh, construct obb tree and get intersection distances
    3  
    4 #include "moab/Core.hpp"
    5 #include "moab/Range.hpp"
    6 #include "moab/OrientedBoxTreeTool.hpp"
    7 #include <iostream>
    8 #include <cmath>
    9  
   10 int main( int argc, char** argv )
   11 {
   12     if( 1 == argc )
   13     {
   14         std::cout << "Usage: " << argv[0] << " <filename>" << std::endl;
   15         return 0;
   16     }
   17  
   18     // instantiate & load a mesh from a file
   19     moab::Core* mb       = new moab::Core();
   20     moab::ErrorCode rval = mb->load_mesh( argv[1] );
   21     if( rval != moab::MB_SUCCESS )
   22     {
   23         std::cerr << "Couldn't load mesh." << std::endl;
   24         delete mb;
   25         return 1;
   26     }
   27  
   28     // get all triangles
   29     moab::EntityHandle tree_root;
   30     moab::Range tris;
   31     // moab::OrientedBoxTreeTool::Settings settings;
   32  
   33     rval = mb->get_entities_by_type( 0, moab::MBTRI, tris );
   34     if( rval != moab::MB_SUCCESS )
   35     {
   36         std::cerr << "Couldn't get triangles." << std::endl;
   37         delete mb;
   38         return 1;
   39     }
   40  
   41     // build OBB trees for all triangles
   42     moab::OrientedBoxTreeTool tool( mb );
   43     // rval = tool.build(tris, tree_root, &settings);
   44     rval = tool.build( tris, tree_root );
   45     if( rval != moab::MB_SUCCESS )
   46     {
   47         std::cerr << "Could'nt build tree." << std::endl;
   48         delete mb;
   49         return 1;
   50     }
   51  
   52     // build box
   53     double box_center[3], box_axis1[3], box_axis2[3], box_axis3[3], pnt_start[3], ray_length;
   54     rval = tool.box( tree_root, box_center, box_axis1, box_axis2, box_axis3 );
   55     if( rval != moab::MB_SUCCESS )
   56     {
   57         std::cerr << "Couldn't get box for tree root set.";
   58         delete mb;
   59         return 1;
   60     }
   61  
   62     ray_length = 2. * sqrt( box_axis1[0] * box_axis1[0] + box_axis1[1] * box_axis1[1] + box_axis1[2] * box_axis1[2] );
   63  
   64     // do ray-tracing from box center side to x direction
   65     std::vector< double > intersections;
   66     std::vector< moab::EntityHandle > intersection_facets;
   67  
   68     for( int i = 0; i < 3; i++ )
   69         pnt_start[i] = box_center[i] - box_axis1[i];
   70  
   71     if( ray_length > 0 )
   72     {  // normalize ray direction
   73         for( int j = 0; j < 3; j++ )
   74             box_axis1[j] = 2 * box_axis1[j] / ray_length;
   75     }
   76     rval = tool.ray_intersect_triangles( intersections, intersection_facets, tree_root, 10e-12, pnt_start, box_axis1,
   77                                          &ray_length );
   78     if( rval != moab::MB_SUCCESS )
   79     {
   80         std::cerr << "Couldn't ray tracing.";
   81         delete mb;
   82         return 1;
   83     }
   84  
   85     std::cout << "ray start point: " << pnt_start[0] << " " << pnt_start[1] << " " << pnt_start[2] << std::endl;
   86     std::cout << " ray direction: " << box_axis1[0] << " " << box_axis1[1] << " " << box_axis1[2] << "\n";
   87     std::cout << "# of intersections : " << intersections.size() << std::endl;
   88     std::cout << "intersection distances are on";
   89     for( unsigned int i = 0; i < intersections.size(); i++ )
   90         std::cout << " " << intersections[i];
   91     std::cout << " of ray length " << ray_length << std::endl;
   92  
   93     delete mb;
   94  
   95     return 0;
   96 }