UnrealEngineUWP/Engine/Plugins/Experimental/ProxyLODPlugin/Source/ThirdParty/DirectXMeshCode/DirectXMesh/DirectXMeshClean.cpp

//-------------------------------------------------------------------------------------
// DirectXMeshClean.cpp
//  
// DirectX Mesh Geometry Library - Mesh clean-up
//
// THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF
// ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO
// THE IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A
// PARTICULAR PURPOSE.
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
// http://go.microsoft.com/fwlink/?LinkID=324981
//-------------------------------------------------------------------------------------

#include "DirectXMeshP.h"

using namespace DirectX;

namespace
{

template<class index_t>
HRESULT _Clean( _Inout_updates_all_(nFaces*3) index_t* indices,
                size_t nFaces, size_t nVerts,
                _Inout_updates_all_opt_(nFaces*3) uint32_t* adjacency,
                _In_reads_opt_(nFaces) const uint32_t* attributes,
                _Inout_ std::vector<uint32_t>& dupVerts, bool breakBowties )
{
    if ( !adjacency && !attributes )
        return E_INVALIDARG;

    if ( ( uint64_t(nFaces) * 3 ) >= UINT32_MAX )
        return HRESULT_FROM_WIN32( ERROR_ARITHMETIC_OVERFLOW );

    dupVerts.clear();
    size_t curNewVert = nVerts;

    size_t tsize = ( sizeof(bool) * nFaces * 3 ) + ( sizeof(uint32_t) * nVerts ) + ( sizeof(index_t) * nFaces * 3 );
    std::unique_ptr<uint8_t[]> temp( new (std::nothrow) uint8_t[ tsize ] );
    if ( !temp )
        return E_OUTOFMEMORY;

    auto faceSeen = reinterpret_cast<bool*>( temp.get() );
    auto ids = reinterpret_cast<uint32_t*>( temp.get() + sizeof(bool) * nFaces * 3 );

    // UNUSED/DEGENERATE cleanup
    for( uint32_t face = 0; face < nFaces; ++face )
    {
        index_t i0 = indices[ face*3 ];
        index_t i1 = indices[ face*3 + 1 ];
        index_t i2 = indices[ face*3 + 2 ];

        if ( i0 == index_t(-1)
             || i1 == index_t(-1)
             || i2 == index_t(-1) )
        {
            // ensure all index entries in the unused face are 'unused'
            indices[ face*3 ] =
            indices[ face*3 + 1 ] =
            indices[ face*3 + 2 ] = index_t(-1);

            // ensure no neighbor references the unused face
            if ( adjacency )
            {
                for( uint32_t point = 0; point < 3; ++point )
                {
                    uint32_t k = adjacency[ face*3 + point ];
                    if ( k != UNUSED32 )
                    {
                        assert( k < nFaces );
                        _Analysis_assume_( k < nFaces );

                        if ( adjacency[ k*3 ] == face )
                            adjacency[ k*3 ] = UNUSED32;

                        if ( adjacency[ k*3 + 1 ] == face )
                            adjacency[ k*3 + 1 ] = UNUSED32;

                        if ( adjacency[ k*3 + 2 ] == face )
                            adjacency[ k*3 + 2 ] = UNUSED32;

                        adjacency[ face*3 + point ] = UNUSED32;
                    }
                }
            }
        }
        else if ( i0 == i1
                  || i0 == i2
                  || i1 == i2 )
        {
            // Clean doesn't trim out degenerates as most other functions ignore them

            // ensure no neighbor references the degenerate face
            if ( adjacency )
            {
                for( uint32_t point = 0; point < 3; ++point )
                {
                    uint32_t k = adjacency[ face*3 + point ];
                    if ( k != UNUSED32 )
                    {
                        assert( k < nFaces );
                        _Analysis_assume_( k < nFaces );

                        if ( adjacency[ k*3 ] == face )
                            adjacency[ k*3 ] = UNUSED32;

                        if ( adjacency[ k*3 + 1 ] == face )
                            adjacency[ k*3 + 1 ] = UNUSED32;

                        if ( adjacency[ k*3 + 2 ] == face )
                            adjacency[ k*3 + 2 ] = UNUSED32;

                        adjacency[ face*3 + point ] = UNUSED32;
                    }
                }
            }
        }
    }

    // ASYMMETRIC ADJ cleanup
    if ( adjacency )
    {
        for(;;)
        {
            bool unlinked = false;

            for( uint32_t face = 0; face < nFaces; ++face )
            {
                for( size_t point = 0; point < 3; ++point )
                {
                    uint32_t k = adjacency[ face*3 + point ];
                    if ( k != UNUSED32 )
                    {
                        assert( k < nFaces );
                        _Analysis_assume_( k < nFaces );

                        uint32_t edge = find_edge<uint32_t>( &adjacency[ k * 3 ], face );
                        if ( edge >= 3 )
                        {
                            unlinked = true;
                            adjacency[ face*3 + point ] = UNUSED32;
                        }
                    }
                }
            }

            if ( !unlinked )
                break;
        }
    }

    // BACKFACING cleanup
    if ( adjacency )
    {
        for( size_t face = 0; face < nFaces; ++face )
        {
            index_t i0 = indices[ face*3 ];
            index_t i1 = indices[ face*3 + 1 ];
            index_t i2 = indices[ face*3 + 2 ];

            if ( i0 == index_t(-1)
                 || i1 == index_t(-1)
                 || i2 == index_t(-1) )
            {
                // ignore unused faces
                continue;
            }

            assert( i0 < nVerts );
            assert( i1 < nVerts );
            assert( i2 < nVerts );

            if ( i0 == i1
                 || i0 == i2
                 || i1 == i2 )
            {
                // ignore degenerate faces
                continue;
            }

            uint32_t j0 = adjacency[ face*3 ];
            uint32_t j1 = adjacency[ face*3 + 1 ];
            uint32_t j2 = adjacency[ face*3 + 2 ];

            if ( ( j0 == j1 && j0 != UNUSED32 )
                 || ( j0 == j2 && j0 != UNUSED32 )
                 || ( j1 == j2 && j1 != UNUSED32 ) )
            {
                uint32_t neighbor;

                if ( j0 == j1 || j0 == j2 )
                {
                    neighbor = j0;
                }
                else
                {
                    neighbor = j1;
                }

                // remove links then break bowties will clean up any remaining issues
                for( uint32_t edge = 0; edge < 3; ++edge )
                {
                    if ( adjacency[ face * 3 + edge ] == neighbor )
                    {
                        adjacency[ face * 3 + edge ] = UNUSED32;
                    }

                    if ( adjacency[ neighbor * 3 + edge ] == face )
                    {
                        adjacency[ neighbor * 3 + edge ] = UNUSED32;
                    }
                }
            }
        }
    }

    auto indicesNew = reinterpret_cast<index_t*>( reinterpret_cast<uint8_t*>( ids ) + sizeof(uint32_t) * nVerts );
    memcpy( indicesNew, indices, sizeof(index_t) * nFaces * 3 );

    // BOWTIES cleanup
    if ( adjacency && breakBowties )
    {
        memset( faceSeen, 0, sizeof(bool) * nFaces * 3 );
        memset( ids, 0xFF, sizeof(uint32_t) * nVerts );

        orbit_iterator<index_t> ovi( adjacency, indices, nFaces );

        for( uint32_t face = 0; face < nFaces; ++face )
        {
            index_t i0 = indices[ face*3 ];
            index_t i1 = indices[ face*3 + 1 ];
            index_t i2 = indices[ face*3 + 2 ];

            if ( i0 == index_t(-1)
                 || i1 == index_t(-1)
                 || i2 == index_t(-1) )
            {
                // ignore unused faces
                faceSeen[ face * 3 ] = true;
                faceSeen[ face * 3 + 1 ] = true;
                faceSeen[ face * 3 + 2 ] = true;
                continue;
            }

            assert( i0 < nVerts );
            assert( i1 < nVerts );
            assert( i2 < nVerts );

            if ( i0 == i1
                 || i0 == i2
                 || i1 == i2 )
            {
                // ignore degenerate faces
                faceSeen[ face * 3 ] = true;
                faceSeen[ face * 3 + 1 ] = true;
                faceSeen[ face * 3 + 2 ] = true;
                continue;
            }

            for( uint32_t point = 0; point < 3; ++point )
            {
                if ( faceSeen[ face * 3 + point ] )
                    continue;

                faceSeen[ face * 3 + point ] = true;

                index_t i = indices[ face*3 + point ];
                if ( i == index_t(-1) )
                    continue;

                assert( i < nVerts );

                ovi.initialize( face, i, orbit_iterator<index_t>::ALL );
                ovi.moveToCCW();

                index_t replaceVertex = index_t(-1);
                index_t replaceValue = index_t(-1);

                while ( !ovi.done() )
                {
                    uint32_t curFace = ovi.nextFace();
                    if ( curFace >= nFaces )
                        return E_FAIL;

                    uint32_t curPoint = ovi.getpoint();
                    if ( curPoint > 2 )
                        return E_FAIL;
 
                    faceSeen[ curFace*3 + curPoint ] = true;

                    index_t j = indices[ curFace * 3 + curPoint ];
                    if ( j == index_t(-1) )
                        continue;

                    assert ( j < nVerts );

                    if ( j == replaceVertex )
                    {
                        indicesNew[ curFace * 3 + curPoint ] = replaceValue;
                    }
                    else if ( ids[ j ] == UNUSED32 )
                    {
                        ids[ j ] = face;
                    }
                    else if ( ids[ j ] != face )
                    {
                        // We found a bowtie, duplicate a vert
                        replaceVertex = j;
                        replaceValue = index_t( curNewVert );
                        indicesNew[ curFace * 3 + curPoint ] = replaceValue;
                        ++curNewVert;

                        dupVerts.push_back( j );
                    }
                }
            }
        }

        assert( ( nVerts + dupVerts.size() ) == curNewVert );
    }

    // Ensure no vertex is used by more than one attribute
    if ( attributes )
    {
        memset( ids, 0xFF, sizeof(uint32_t) * nVerts );

        std::vector<uint32_t> dupAttr;
        dupAttr.reserve( dupVerts.size() );
        for( size_t j = 0; j < dupVerts.size(); ++j )
        {
            dupAttr.push_back( UNUSED32 );
        }
        
        std::unordered_multimap<uint32_t,size_t> dups;

        for( size_t face = 0; face < nFaces; ++face )
        {
            uint32_t a = attributes[ face ];

            for( size_t point = 0; point < 3; ++point )
            {
                uint32_t j = indicesNew[ face*3 + point ];

                uint32_t k = ( j >= nVerts ) ? dupAttr[ j - nVerts ] : ids[ j ];

                if ( k == UNUSED32 )
                {
                    if ( j >= nVerts )
                        dupAttr[ j - nVerts ] = a;
                    else
                        ids[ j ] = a;
                }
                else if ( k != a )
                {
                    // Look for a dup with the correct attribute
                    auto range = dups.equal_range( j );
                    auto it = range.first;
                    for( ; it != range.second; ++it )
                    {
                        uint32_t m = ( it->second >= nVerts ) ? dupAttr[ it->second - nVerts ] : ids[ it->second ];
                        if ( m == a )
                        {
                            indicesNew[ face * 3 + point ] = index_t( it->second );
                            break;
                        }
                    }

                    if ( it == range.second )
                    {                        
                        // Duplicate the vert
                        dups.insert( std::pair<uint32_t,size_t>( j, curNewVert ) );

                        indicesNew[ face * 3 + point ] = index_t( curNewVert );
                        ++curNewVert;

                        if ( j >= nVerts )
                        {
                            dupVerts.push_back( dupVerts[ j - nVerts ] );
                        }
                        else
                        {
                            dupVerts.push_back( j );
                        }

                        dupAttr.push_back( a );

                        assert( dupVerts.size() == dupAttr.size() );
                    }
                }
            }
        }

        assert( ( nVerts + dupVerts.size() ) == curNewVert );

#ifndef NDEBUG
        for( auto it = dupVerts.begin(); it != dupVerts.end(); ++it )
        {
            assert( *it < nVerts );
        }
#endif
    }

    if ( (uint64_t(nVerts) + uint64_t(dupVerts.size()) ) >= index_t(-1) )
        return HRESULT_FROM_WIN32( ERROR_ARITHMETIC_OVERFLOW );

    if ( !dupVerts.empty() )
    {
        memcpy( indices, indicesNew, sizeof(index_t) * nFaces * 3 );
    }

    return S_OK;
}

};

namespace DirectX
{

//=====================================================================================
// Entry-points
//=====================================================================================

//-------------------------------------------------------------------------------------
_Use_decl_annotations_
HRESULT Clean( uint16_t* indices, size_t nFaces, size_t nVerts, uint32_t* adjacency, const uint32_t* attributes,
               std::vector<uint32_t>& dupVerts, bool breakBowties )
{
    HRESULT hr = Validate( indices, nFaces, nVerts, adjacency, VALIDATE_DEFAULT );
    if ( FAILED(hr) )
        return hr;

    return _Clean<uint16_t>( indices, nFaces, nVerts, adjacency, attributes, dupVerts, breakBowties );
}


//-------------------------------------------------------------------------------------
_Use_decl_annotations_
HRESULT Clean( uint32_t* indices, size_t nFaces, size_t nVerts, uint32_t* adjacency, const uint32_t* attributes,
               std::vector<uint32_t>& dupVerts, bool breakBowties )
{
    HRESULT hr = Validate( indices, nFaces, nVerts, adjacency, VALIDATE_DEFAULT );
    if ( FAILED(hr) )
        return hr;

    return _Clean<uint32_t>( indices, nFaces, nVerts, adjacency, attributes, dupVerts, breakBowties );
}

} // namespace