BV_splitter.h

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#ifndef FCL_BV_SPLITTER_H
#define FCL_BV_SPLITTER_H

#include "fcl/BVH/BVH_internal.h"
#include "fcl/BV/kIOS.h"
#include "fcl/BV/OBBRSS.h"
#include <vector>
#include <iostream>

namespace fcl
{

template<typename BV>
class BVSplitterBase
{
public:
  virtual void set(Vec3f* vertices_, Triangle* tri_indices_, BVHModelType type_) = 0;

  virtual void computeRule(const BV& bv, unsigned int* primitive_indices, int num_primitives) = 0;

  virtual bool apply(const Vec3f& q) const = 0;

  virtual void clear() = 0;
};


enum SplitMethodType {SPLIT_METHOD_MEAN, SPLIT_METHOD_MEDIAN, SPLIT_METHOD_BV_CENTER};


template<typename BV>
class BVSplitter : public BVSplitterBase<BV>
{
public:

  BVSplitter(SplitMethodType method) : split_method(method)
  {
  }

  virtual ~BVSplitter() {}

  void set(Vec3f* vertices_, Triangle* tri_indices_, BVHModelType type_)
  {
    vertices = vertices_;
    tri_indices = tri_indices_;
    type = type_;
  }

  void computeRule(const BV& bv, unsigned int* primitive_indices, int num_primitives)
  {
    switch(split_method)
    {
    case SPLIT_METHOD_MEAN:
      computeRule_mean(bv, primitive_indices, num_primitives);
      break;
    case SPLIT_METHOD_MEDIAN:
      computeRule_median(bv, primitive_indices, num_primitives);
      break;
    case SPLIT_METHOD_BV_CENTER:
      computeRule_bvcenter(bv, primitive_indices, num_primitives);
      break;
    default:
      std::cerr << "Split method not supported" << std::endl;
    }
  }

  bool apply(const Vec3f& q) const
  {
    return q[split_axis] > split_value;
  }

  void clear()
  {
    vertices = NULL;
    tri_indices = NULL;
    type = BVH_MODEL_UNKNOWN;
  }

private:

  int split_axis;
  Vec3f split_vector;

  FCL_REAL split_value;

  Vec3f* vertices;

  Triangle* tri_indices;

  BVHModelType type;

  SplitMethodType split_method;

  void computeRule_bvcenter(const BV& bv, unsigned int* primitive_indices, int num_primitives)
  {
    Vec3f center = bv.center();
    int axis = 2;

    if(bv.width() >= bv.height() && bv.width() >= bv.depth())
      axis = 0;
    else if(bv.height() >= bv.width() && bv.height() >= bv.depth())
      axis = 1;

    split_axis = axis;
    split_value = center[axis];
  }

  void computeRule_mean(const BV& bv, unsigned int* primitive_indices, int num_primitives)
  {
    int axis = 2;

    if(bv.width() >= bv.height() && bv.width() >= bv.depth())
      axis = 0;
    else if(bv.height() >= bv.width() && bv.height() >= bv.depth())
      axis = 1;

    split_axis = axis;
    FCL_REAL sum = 0;

    if(type == BVH_MODEL_TRIANGLES)
    {
      for(int i = 0; i < num_primitives; ++i)
      {
        const Triangle& t = tri_indices[primitive_indices[i]];
        sum += (vertices[t[0]][split_axis] + vertices[t[1]][split_axis] + vertices[t[2]][split_axis]);
      }

      sum /= 3;
    }
    else if(type == BVH_MODEL_POINTCLOUD)
    {
      for(int i = 0; i < num_primitives; ++i)
      {
        sum += vertices[primitive_indices[i]][split_axis];
      }
    }

    split_value = sum / num_primitives;
  }

  void computeRule_median(const BV& bv, unsigned int* primitive_indices, int num_primitives)
  {
    int axis = 2;

    if(bv.width() >= bv.height() && bv.width() >= bv.depth())
      axis = 0;
    else if(bv.height() >= bv.width() && bv.height() >= bv.depth())
      axis = 1;

    split_axis = axis;
    std::vector<FCL_REAL> proj(num_primitives);

    if(type == BVH_MODEL_TRIANGLES)
    {
      for(int i = 0; i < num_primitives; ++i)
      {
        const Triangle& t = tri_indices[primitive_indices[i]];
        proj[i] = (vertices[t[0]][split_axis] + vertices[t[1]][split_axis] + vertices[t[2]][split_axis]) / 3;
      }
    }
    else if(type == BVH_MODEL_POINTCLOUD)
    {
      for(int i = 0; i < num_primitives; ++i)
        proj[i] = vertices[primitive_indices[i]][split_axis];
    }

    std::sort(proj.begin(), proj.end());

    if(num_primitives % 2 == 1)
    {
      split_value = proj[(num_primitives - 1) / 2];
    }
    else
    {
      split_value = (proj[num_primitives / 2] + proj[num_primitives / 2 - 1]) / 2;
    }
  }
};


template<>
bool BVSplitter<OBB>::apply(const Vec3f& q) const;

template<>
bool BVSplitter<RSS>::apply(const Vec3f& q) const;

template<>
bool BVSplitter<kIOS>::apply(const Vec3f& q) const;

template<>
bool BVSplitter<OBBRSS>::apply(const Vec3f& q) const;

template<>
void BVSplitter<OBB>::computeRule_bvcenter(const OBB& bv, unsigned int* primitive_indices, int num_primitives);

template<>
void BVSplitter<OBB>::computeRule_mean(const OBB& bv, unsigned int* primitive_indices, int num_primitives);

template<>
void BVSplitter<OBB>::computeRule_median(const OBB& bv, unsigned int* primitive_indices, int num_primitives);

template<>
void BVSplitter<RSS>::computeRule_bvcenter(const RSS& bv, unsigned int* primitive_indices, int num_primitives);
          
template<>                        
void BVSplitter<RSS>::computeRule_mean(const RSS& bv, unsigned int* primitive_indices, int num_primitives);

template<>
void BVSplitter<RSS>::computeRule_median(const RSS& bv, unsigned int* primitive_indices, int num_primitives);

template<>
void BVSplitter<kIOS>::computeRule_bvcenter(const kIOS& bv, unsigned int* primitive_indices, int num_primitives);

template<>
void BVSplitter<kIOS>::computeRule_mean(const kIOS& bv, unsigned int* primitive_indices, int num_primitives);

template<>
void BVSplitter<kIOS>::computeRule_median(const kIOS& bv, unsigned int* primitive_indices, int num_primitives);

template<>
void BVSplitter<OBBRSS>::computeRule_bvcenter(const OBBRSS& bv, unsigned int* primitive_indices, int num_primitives);

template<>
void BVSplitter<OBBRSS>::computeRule_mean(const OBBRSS& bv, unsigned int* primitive_indices, int num_primitives);

template<>
void BVSplitter<OBBRSS>::computeRule_median(const OBBRSS& bv, unsigned int* primitive_indices, int num_primitives);

}

#endif