FixPolys.cpp File Reference

Example demonstrating how to fix polygons with duplicated vertices. More...

#include <iostream>
#include <cstdlib>
#include <cstdio>
#include "moab/Core.hpp"
#include "moab/Interface.hpp"
#include "moab/Range.hpp"
#include "moab/ProgOptions.hpp"

Include dependency graph for FixPolys.cpp:

Go to the source code of this file.

Functions
int	main (int argc, char **argv)

Detailed Description

Example demonstrating how to fix polygons with duplicated vertices.

This example shows how to:

• Load a mesh file containing polygons
• Identify polygons with duplicated vertices
• Remove consecutive duplicate vertices from polygon connectivity
• Create new polygons with cleaned connectivity
• Preserve global ID tags during polygon reconstruction
• Write the corrected mesh to a new file

The program is useful for cleaning up meshes that have been created with padded vertices to reduce data sequences, but now need to be optimized by removing redundant vertex references.

Author

MOAB Development Team

Date

2024

This test shows how to fix polygons that have duplicated vertices

We sometimes use padded vertices option, to reduce the number of data sequences We identify first the polygons that have padded vertices then we set the new ones with reduced number of vertices, but with the same global id tag

Parameters

argc	Number of command line arguments
argv	Command line arguments array

Returns

0 on success, 1 on failure

Definition in file FixPolys.cpp.

Function Documentation

main()

int main	(	int	argc,
		char **	argv
	)

Definition at line 47 of file FixPolys.cpp.

{
    ProgOptions opts;
 
    string inputFile = test_file_name;
    opts.addOpt< string >( "inFile,i", "Specify the input file name string ", &inputFile );
 
    string outFile = "out.h5m";
    opts.addOpt< string >( "outFile,o", "Specify the output file name string ", &outFile );
 
    opts.parseCommandLine( argc, argv );
 
    // Instantiate
    Core mb;
 
    MB_CHK_SET_ERR( mb.load_file( inputFile.c_str() ), "Error loading file" );
 
    cout << " reading file " << inputFile << "\n";
 
    // Get all 2d elements in the file set
    Range elems;
    MB_CHK_SET_ERR( mb.get_entities_by_dimension( 0, 2, elems ), "Error getting 2d elements" );
 
    cout << "number of cells: " << elems.size() << "\n";
 
    Tag gidTag = mb.globalId_tag();
    Range OldCells;
    for( Range::iterator it = elems.begin(); it != elems.end(); ++it )
    {
        EntityHandle cell = *it;
        const EntityHandle* conn;
        int number_nodes;
        MB_CHK_SET_ERR( mb.get_connectivity( cell, conn, number_nodes ), "Error getting connectivity" );
        // now check if we have consecutive duplicated vertices, and if so, create a new cell
        std::vector< EntityHandle > new_verts;
        // push to it, if we do not have duplicates
 
        EntityHandle current = conn[0];
        // new_verts.push_back(current);
        for( int i = 1; i <= number_nodes; i++ )
        {
            EntityHandle nextV;
            if( i < number_nodes )
                nextV = conn[i];
            else
                nextV = conn[0];  // first vertex
            if( current != nextV )
            {
                new_verts.push_back( current );
                current = nextV;
            }
        }
        if( number_nodes > (int)new_verts.size() )
        {
            // create a new poly, and put this in a list to be removed
            int gid;
            MB_CHK_SET_ERR( mb.tag_get_data( gidTag, &cell, 1, &gid ), "Error getting global id tag" );
            EntityHandle newCell;
            MB_CHK_SET_ERR( mb.create_element( MBPOLYGON, &new_verts[0], (int)new_verts.size(), newCell ),
                            "Error creating new polygon " );
            MB_CHK_SET_ERR( mb.tag_set_data( gidTag, &newCell, 1, &gid ), "Error setting global id tag" );
            cout << "delete old cell " << cell << " with num_nodes vertices: " << number_nodes
                 << " and with global id: " << gid << "\n";
            for( int i = 0; i < number_nodes; i++ )
            {
                cout << " " << conn[i];
            }
            cout << "\n";
            OldCells.insert( cell );
        }
        mb.delete_entities( OldCells );
    }
    MB_CHK_SET_ERR( mb.write_file( outFile.c_str() ), "Error writing file" );
 
    return 0;
}

References ProgOptions::addOpt(), moab::Range::begin(), moab::Core::create_element(), moab::Core::delete_entities(), moab::Range::end(), moab::Core::get_connectivity(), moab::Core::get_entities_by_dimension(), moab::Core::globalId_tag(), moab::Range::insert(), moab::Core::load_file(), mb, MB_CHK_SET_ERR, MBPOLYGON, ProgOptions::parseCommandLine(), moab::Range::size(), moab::Core::tag_get_data(), moab::Core::tag_set_data(), test_file_name, and moab::Core::write_file().