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       1                 :            : /**
       2                 :            :  * MOAB, a Mesh-Oriented datABase, is a software component for creating,
       3                 :            :  * storing and accessing finite element mesh data.
       4                 :            :  *
       5                 :            :  * Copyright 2004 Sandia Corporation.  Under the terms of Contract
       6                 :            :  * DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government
       7                 :            :  * retains certain rights in this software.
       8                 :            :  *
       9                 :            :  * This library is free software; you can redistribute it and/or
      10                 :            :  * modify it under the terms of the GNU Lesser General Public
      11                 :            :  * License as published by the Free Software Foundation; either
      12                 :            :  * version 2.1 of the License, or (at your option) any later version.
      13                 :            :  *
      14                 :            :  */
      15                 :            : 
      16                 :            : /**
      17                 :            :  * \class AffineXform
      18                 :            :  * \brief Define an affine transformatino
      19                 :            :  * \author Jason Kraftcheck ([email protected])
      20                 :            :  * \date August, 2006
      21                 :            :  */
      22                 :            : 
      23                 :            : #ifdef WIN32               /* windows */
      24                 :            : #define _USE_MATH_DEFINES  // For M_PI
      25                 :            : #endif
      26                 :            : 
      27                 :            : #include "AffineXform.hpp"
      28                 :            : #include "moab/Interface.hpp"
      29                 :            : #include <assert.h>
      30                 :            : 
      31                 :            : namespace moab
      32                 :            : {
      33                 :            : 
      34                 :            : // Don't include tag-related stuff in test build because we don't
      35                 :            : // link to MOAB to test all other functionality.
      36                 :            : const char* const AFFINE_XFORM_TAG_NAME = "AFFINE_TRANSFORM";
      37                 :            : 
      38                 :          0 : ErrorCode AffineXform::get_tag( Tag& tag_out, Interface* interface, const char* tagname )
      39                 :            : {
      40         [ #  # ]:          0 :     assert( sizeof( AffineXform ) == 12 * sizeof( double ) );
      41                 :            : 
      42         [ #  # ]:          0 :     if( !tagname ) tagname = AFFINE_XFORM_TAG_NAME;
      43                 :            : 
      44                 :            :     return interface->tag_get_handle( tagname, sizeof( AffineXform ), MB_TYPE_DOUBLE, tag_out,
      45                 :          0 :                                       MB_TAG_BYTES | MB_TAG_CREAT | MB_TAG_DENSE );
      46                 :            : }
      47                 :            : 
      48                 :          2 : AffineXform AffineXform::rotation( const double* from_vec, const double* to_vec )
      49                 :            : {
      50         [ +  - ]:          2 :     CartVect from( from_vec );
      51         [ +  - ]:          2 :     CartVect to( to_vec );
      52         [ +  - ]:          2 :     CartVect a = from * to;
      53         [ +  - ]:          2 :     double len = a.length();
      54                 :            : 
      55                 :            :     // If input vectors are not parallel (the normal case)
      56         [ +  + ]:          2 :     if( len >= std::numeric_limits< double >::epsilon() )
      57                 :            :     {
      58         [ +  - ]:          1 :         from.normalize();
      59         [ +  - ]:          1 :         to.normalize();
      60 [ +  - ][ +  - ]:          1 :         return rotation( from % to, ( from * to ).length(), a / len );
         [ +  - ][ +  - ]
                 [ +  - ]
      61                 :            :     }
      62                 :            : 
      63                 :            :     // Vectors are parallel:
      64                 :            :     //
      65                 :            :     // If vectors are in same direction then rotation is identity (no transform)
      66 [ +  - ][ -  + ]:          1 :     if( from % to >= 0.0 ) return AffineXform();
                 [ #  # ]
      67                 :            : 
      68                 :            :     // Parallel vectors in opposite directions:
      69                 :            :     //
      70                 :            :     // NOTE:  This case is ill-defined.  There are infinitely
      71                 :            :     // many rotations that can align the two vectors.  The angle
      72                 :            :     // of rotation is 180 degrees, but the axis of rotation may
      73                 :            :     // be any unit vector orthogonal to the input vectors.
      74                 :            :     //
      75         [ +  - ]:          1 :     from.normalize();
      76 [ +  - ][ +  - ]:          1 :     double lenxy = std::sqrt( from[0] * from[0] + from[1] * from[1] );
         [ +  - ][ +  - ]
      77 [ +  - ][ +  - ]:          1 :     CartVect axis( -from[0] * from[2] / lenxy, -from[1] * from[2] / lenxy, lenxy );
         [ +  - ][ +  - ]
                 [ +  - ]
      78         [ +  - ]:          2 :     return rotation( -1, 0, axis );
      79                 :            : }
      80                 :            : 
      81 [ +  - ][ +  - ]:          4 : }  // namespace moab