Function orient3d

source/MRMesh/MRPrecisePredicates3.cpp:111–153

} // anonymous namespace

bool orient3d( const Vector3i & a, const Vector3i& b, const Vector3i& c )
{
    auto vhp = dot( Vector3i128fast{ a }, Vector3i128fast{ cross( Vector3i64{ b }, Vector3i64{ c } ) } );
    if ( vhp ) return vhp > 0;

    auto v = cross( Vector2i64{ b.x, b.y }, Vector2i64{ c.x, c.y } );
    if ( v ) return v > 0;

    v = -cross( Vector2i64{ b.x, b.z }, Vector2i64{ c.x, c.z } );
    if ( v ) return v > 0;

    v = cross( Vector2i64{ b.y, b.z }, Vector2i64{ c.y, c.z } );
    if ( v ) return v > 0;

    v = -cross( Vector2i64{ a.x, a.y }, Vector2i64{ c.x, c.y } );
    if ( v ) return v > 0;

    if ( c.x ) return c.x > 0;

    if ( c.y ) return c.y < 0;

    v = cross( Vector2i64{ a.x, a.z }, Vector2i64{ c.x, c.z } );
    if ( v ) return v > 0;

    if ( c.z ) return c.z > 0;

#ifndef NDEBUG
    v = -cross( Vector2i64{ a.y, a.z }, Vector2i64{ c.y, c.z } );
    assert( v == 0 );
    if ( v ) return v > 0;
#endif

    v = cross( Vector2i64{ a.x, a.y }, Vector2i64{ b.x, b.y } );
    if ( v ) return v > 0;

    if ( b.x ) return b.x < 0;

    if ( b.y ) return b.y > 0;

    if ( a.x ) return a.x > 0;

    return true;
}

bool orient3d( const PreciseVertCoords* vs )
{