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DT_Box.cpp

/*
 * SOLID - Software Library for Interference Detection
 * 
 * Copyright (C) 2001-2003  Dtecta.  All rights reserved.
 *
 * This library may be distributed under the terms of the Q Public License
 * (QPL) as defined by Trolltech AS of Norway and appearing in the file
 * LICENSE.QPL included in the packaging of this file.
 *
 * This library may be distributed and/or modified under the terms of the
 * GNU General Public License (GPL) version 2 as published by the Free Software
 * Foundation and appearing in the file LICENSE.GPL included in the
 * packaging of this file.
 *
 * This library is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 * Commercial use or any other use of this library not covered by either 
 * the QPL or the GPL requires an additional license from Dtecta. 
 * Please contact info@dtecta.com for enquiries about the terms of commercial
 * use of this library.
 */

#include "DT_Box.h"

MT_Scalar DT_Box::supportH(const MT_Vector3& v) const 
{
    return v.absolute().dot(m_extent);
}

MT_Point3 DT_Box::support(const MT_Vector3& v) const 
{
    return MT_Point3(v[0] < MT_Scalar(0.0) ? -m_extent[0] : m_extent[0],
                     v[1] < MT_Scalar(0.0) ? -m_extent[1] : m_extent[1],
                     v[2] < MT_Scalar(0.0) ? -m_extent[2] : m_extent[2]); 
    
}


bool DT_Box::ray_cast(const MT_Point3& source, const MT_Point3& target,
                                MT_Scalar& param, MT_Vector3& normal) const 
{
      T_Outcode source_bits = outcode(source);
      T_Outcode target_bits = outcode(target);

      if ((source_bits & target_bits) == 0x0)
            // None of the side planes separate the ray from the box.
      {
            MT_Scalar lambda_enter = MT_Scalar(0.0);
            MT_Scalar lambda_exit  = param;
            MT_Vector3 r = target - source;
            T_Outcode normal_bit = 0x0; // Indicates the axis that is returned as normal.
            T_Outcode bit = 0x01;
            int i;
            for (i = 0; i != 3; ++i)
            {
                  if (source_bits & bit)
                        // Point of intersection is entering
                  {
                        MT_Scalar lambda = (-source[i] - m_extent[i]) / r[i];
                        if (lambda_enter < lambda)
                        {
                              lambda_enter = lambda;
                              normal_bit = bit;
                        }
                  }
                  else if (target_bits & bit) 
                        // Point of intersection is exiting
                  {
                        MT_Scalar lambda = (-source[i] - m_extent[i]) / r[i];
                        GEN_set_min(lambda_exit, lambda);
                  }
                  bit <<=1;
                  if (source_bits & bit)
                        // Point of intersection is entering
                  {
                        MT_Scalar lambda =  (-source[i] + m_extent[i]) / r[i];
                        if (lambda_enter < lambda)
                        {
                              lambda_enter = lambda;
                              normal_bit = bit;
                        }
                  }
                  else if (target_bits & bit) 
                        // Point of intersection is exiting
                  {
                        MT_Scalar lambda =  (-source[i] + m_extent[i]) / r[i];
                        GEN_set_min(lambda_exit, lambda);
                  }
                  bit <<=1;
            }
            if (lambda_enter <= lambda_exit)
                  // The ray intersects the box
            {
                  param = lambda_enter;
                  normal.setValue(normal_bit == 0x01 ? -MT_Scalar(1.0) : 
                                          normal_bit == 0x02 ?  MT_Scalar(1.0) : 
                                          MT_Scalar(0.0),
                                          normal_bit == 0x04 ? -MT_Scalar(1.0) : 
                                          normal_bit == 0x08 ?  MT_Scalar(1.0) : 
                                          MT_Scalar(0.0),
                                          normal_bit == 0x10 ? -MT_Scalar(1.0) : 
                                          normal_bit == 0x20 ?  MT_Scalar(1.0) : 
                                          MT_Scalar(0.0));
                  return true;
            }
      }

      return false;
}



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