d2toindex.cpp

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#include <particle.h>
#include <d2toindex.h>

d2toindex::d2toindex
(
  boxcollision const & box_
)
  : pi(0), box(box_), nb(new uint[9]), W(0) 
{
}


d2toindex::d2toindex
(
  particle const * pi_,
  boxcollision const & box_
)
  : pi(pi_), box(box_), nb(new uint[9]), W(0) 
{
}


d2toindex::~d2toindex()
{ 
  delete[] nb; 
}
  
void d2toindex::reset()
{ 
  assert(box.x1-box.x0!=0.0);
  assert(box.y1-box.y0!=0.0);
  xleninv = 1.0/(box.x1-box.x0);
  yleninv = 1.0/(box.y1-box.y0);
}

intc d2toindex::index(uintc i) const
{
  assert(W!=0);
  assert(pi!=0);

  particle const & p(pi[i]);
  // cout << SHOW(p) << endl;
  //double x = (p.pos[0]-box.x0)/(box.x1-box.x0);
  //double y = 1.0 - (p.pos[1]-box.y0)/(box.y1-box.y0);
  double x = (p.pos[0]-box.x0)*xleninv; 
  double y = 1.0 - (p.pos[1]-box.y0)*yleninv;
  //cout << SHOW(x) << endl;
  //cout << SHOW(y) << endl;
  int ix = (int)(x*W) % W;
  int iy = (int)(y*W) % W;
  //cout << SHOW(ix) << endl;
  //cout << SHOW(iy) << endl;
  return ix + W*iy;
}

void d2toindex::getsurroundingcells
(
  uint * & nb_,
  uint & sz,
  uintc k
)
{
  assert(W!=0);
  boolc above = (k>=W);
  boolc left = ((k%W)!=0);
  boolc below = (k+W<W*W);
  boolc right = ((k%W)!=W-1);

  uint index(0);

  nb[index++] = k;

  if (left)
  {
    nb[index++] = k-1;
    if (above)
      nb[index++] = k-W-1;
    if (below)
      nb[index++] = k+W-1;
  }

  if (right)
  {
    nb[index++] = k+1;
    if (above)
      nb[index++] = k-W+1;
    if (below)
      nb[index++] = k+W+1;
  }

  if (above)
    nb[index++] = k-W;

  if (below)
    nb[index++] = k+W;
  
  // finish
  nb_ = nb;
  sz = index;
}