MOAB: Mesh Oriented datABase
(version 5.2.1)
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00001 #include <iostream> 00002 #include <stdlib.h> 00003 #include "MBCore.hpp" 00004 #include "MBRange.hpp" 00005 #include "MBTagConventions.hpp" 00006 00007 // Hold edges in an array of vertex handles. 00008 struct edge 00009 { 00010 MBEntityHandle v0; 00011 MBEntityHandle v1; 00012 }; 00013 00014 // edge structure comparision function for qsort 00015 // If the first vertex handle is the same, compare the second. 00016 int compare_edge( const void* a, const void* b ) 00017 { 00018 struct edge* ia = (struct edge*)a; 00019 struct edge* ib = (struct edge*)b; 00020 if( ia->v0 == ib->v0 ) { return (int)( 100.f * ia->v1 - 100.f * ib->v1 ); } 00021 else 00022 { 00023 return (int)( 100.f * ia->v0 - 100.f * ib->v0 ); 00024 } 00025 } 00026 00027 // This skinner is fast partly because it assumes that no edges exist in the MOAB 00028 // instance. Checking to see if an edge exists before creating a new one is slow. 00029 MBErrorCode skin_tris( MBInterface* mb, MBRange tris, MBRange& skin_edges ) 00030 { 00031 00032 // Empty the output range and make sure that the input range is only tris 00033 skin_edges.clear(); 00034 if( tris.empty() ) return MB_ENTITY_NOT_FOUND; 00035 if( !tris.all_of_type( MBTRI ) ) return MB_FAILURE; 00036 00037 // Remove edges from the instance. 00038 int n_edges; 00039 MBErrorCode rval = mb->get_number_entities_by_type( 0, MBEDGE, n_edges ); 00040 if( MB_SUCCESS != rval ) return rval; 00041 if( 0 != n_edges ) 00042 { 00043 std::cerr << "skin_tris: failed because " << n_edges << " edges exist in the MOAB instance" << std::endl; 00044 return MB_FAILURE; 00045 } 00046 00047 // Get connectivity. Do not create MBEdges. 00048 edge* edges = new edge[3 * tris.size()]; 00049 int n_verts; 00050 int ii = 0; 00051 for( MBRange::iterator i = tris.begin(); i != tris.end(); ++i ) 00052 { 00053 const MBEntityHandle* conn; 00054 rval = mb->get_connectivity( *i, conn, n_verts ); 00055 if( MB_SUCCESS != rval ) return rval; 00056 if( 3 != n_verts ) return MB_FAILURE; 00057 // points should not be degenerate 00058 if( conn[0] == conn[1] || conn[1] == conn[2] || conn[2] == conn[0] ) 00059 { 00060 std::cerr << "skin_tris: degenerate triangle" << std::endl; 00061 return MB_FAILURE; 00062 } 00063 00064 // make edges 00065 edges[3 * ii + 0].v0 = conn[0]; 00066 edges[3 * ii + 0].v1 = conn[1]; 00067 edges[3 * ii + 1].v0 = conn[1]; 00068 edges[3 * ii + 1].v1 = conn[2]; 00069 edges[3 * ii + 2].v0 = conn[2]; 00070 edges[3 * ii + 2].v1 = conn[0]; 00071 ii++; 00072 } 00073 00074 // Ensure that the first vertex handle is the lowest 00075 for( unsigned int i = 0; i < 3 * tris.size(); ++i ) 00076 { 00077 if( edges[i].v0 > edges[i].v1 ) 00078 { 00079 MBEntityHandle temp = edges[i].v0; 00080 edges[i].v0 = edges[i].v1; 00081 edges[i].v1 = temp; 00082 } 00083 } 00084 00085 // Sort by first handle, then second handle. 00086 qsort( edges, 3 * tris.size(), sizeof( struct edge ), compare_edge ); 00087 00088 // Go through array, saving edges that are not paired. 00089 for( unsigned int i = 0; i < 3 * tris.size(); i++ ) 00090 { 00091 // If the last edge has not been paired, create it. This avoids overrunning 00092 // the edges array with i+1. 00093 if( 3 * tris.size() - 1 == i ) 00094 { 00095 const MBEntityHandle conn[2] = { edges[i].v0, edges[i].v1 }; 00096 MBEntityHandle edge; 00097 rval = mb->create_element( MBEDGE, conn, 2, edge ); 00098 if( MB_SUCCESS != rval ) return rval; 00099 skin_edges.insert( edge ); 00100 00101 // If a match exists, skip ahead 00102 } 00103 else if( edges[i].v0 == edges[i + 1].v0 && edges[i].v1 == edges[i + 1].v1 ) 00104 { 00105 i++; 00106 // test to make sure surface is manifold 00107 while( edges[i].v0 == edges[i + 1].v0 && edges[i].v1 == edges[i + 1].v1 ) 00108 { 00109 std::cout << "find_skin WARNING: non-manifold edge" << std::endl; 00110 mb->list_entity( edges[i].v0 ); 00111 mb->list_entity( edges[i].v1 ); 00112 ++i; 00113 } 00114 // otherwise a skin edge has been found 00115 } 00116 else 00117 { 00118 const MBEntityHandle conn[2] = { edges[i].v0, edges[i].v1 }; 00119 MBEntityHandle edge; 00120 rval = mb->create_element( MBEDGE, conn, 2, edge ); 00121 if( MB_SUCCESS != rval ) return rval; 00122 skin_edges.insert( edge ); 00123 } 00124 } 00125 delete[] edges; 00126 return MB_SUCCESS; 00127 } 00128 00129 // Skin triangles to recover edges. 00130 // Triangles are contained in surface sets. 00131 int main( int argc, char** argv ) 00132 { 00133 if( 1 == argc ) 00134 { 00135 std::cout << "Usage: " << argv[0] << " <filename>" << std::endl; 00136 return 0; 00137 } 00138 00139 // get MOAB instance and read the file 00140 MBCore* mb = new MBCore(); 00141 MBErrorCode rval = mb->load_file( argv[1] ); 00142 if( MB_SUCCESS != rval ) return 0; 00143 00144 // this optimized skinner requires removing all MBEdges from the MOAB instance 00145 MBRange edges; 00146 rval = mb->get_entities_by_type( 0, MBEDGE, edges ); 00147 if( MB_SUCCESS != rval ) return 0; 00148 if( !edges.empty() ) std::cout << "Warning: deleting all MBEdges" << std::endl; 00149 rval = mb->delete_entities( edges ); 00150 if( MB_SUCCESS != rval ) return 0; 00151 00152 // get surface sets 00153 MBTag geom_tag; 00154 rval = mb->tag_get_handle( GEOM_DIMENSION_TAG_NAME, 1, MB_TYPE_INTEGER, geom_tag ); 00155 if( MB_SUCCESS != rval ) return 0; 00156 MBRange surf_sets; 00157 int two = 2; 00158 void* dim[] = { &two }; 00159 rval = mb->get_entities_by_type_and_tag( 0, MBENTITYSET, &geom_tag, dim, 1, surf_sets ); 00160 if( MB_SUCCESS != rval ) return 0; 00161 00162 // skin each surface 00163 for( MBRange::iterator i = surf_sets.begin(); i != surf_sets.end(); ++i ) 00164 { 00165 00166 // get triangles in the surface set 00167 MBRange tris; 00168 rval = mb->get_entities_by_type( *i, MBTRI, tris ); 00169 if( MB_SUCCESS != rval ) return 0; 00170 00171 // call the skinning function 00172 MBRange skin_edges; 00173 rval = skin_tris( mb, tris, skin_edges ); 00174 if( MB_SUCCESS != rval ) return 0; 00175 00176 // do something with the result 00177 std::cout << "surface has " << skin_edges.size() << " skin edges" << std::endl; 00178 00179 // remove the edges for the optimized skinner 00180 rval = mb->delete_entities( skin_edges ); 00181 if( MB_SUCCESS != rval ) return 0; 00182 } 00183 }