cosmotool/src/cic.cpp

#include <assert.h>
#include <math.h>
#include <inttypes.h>
#include "cic.hpp"

CICFilter::CICFilter(uint32_t N, double len)
{
  spatialLen = len;
  szGrid = N;
  totalSize = N*N*N;
  densityGrid = new CICType[totalSize];
  resetMesh();
}

CICFilter::~CICFilter()
{
  delete[] densityGrid;
}
  
void CICFilter::resetMesh()
{
  for (uint32_t i = 0; i < totalSize; i++)
    densityGrid[i] = 0;
}

void CICFilter::putParticles(CICParticles *particles, uint32_t N)
{
#if 0
  uint32_t numCorners = 1 << NUMDIMS;

  for (uint32_t i = 0; i < N; i++)
    {
      Coordinates xyz;
      int32_t ixyz[NUMDIMS];
      int32_t rxyz[NUMDIMS];
      CICType alpha[NUMDIMS];
      CICType beta[NUMDIMS];
      for (int j = 0; j < NUMDIMS; j++)
	{
	  xyz[j] = (particles[i].coords[j] / spatialLen * szGrid);
	  ixyz[j] = (int32_t)floor(xyz[j] - 0.5);
	  beta[j] = xyz[j] - ixyz[j] - 0.5;
	  alpha[j] = 1 - beta[j];
	  if (ixyz[j] < 0)
	    ixyz[j] = szGrid-1;
	}

      CICType tot_mass = 0;
      for (int j = 0; j < numCorners; j++)
	{
	  CICType rel_mass = 1;
	  uint32_t idx = 0;
	  uint32_t mul = 1;
	  uint32_t mul2 = 1;

	  for (int k = 0; k < NUMDIMS; k++)
	    {
	      uint32_t ipos = ((j & mul2) != 0);

	      if (ipos == 1)
		{
		  rel_mass *= beta[k];
		}
	      else
		{
		  rel_mass *= alpha[k];
		}

	      rxyz[k] = ixyz[k] + ipos;
	      
	      if (rxyz[k] >= szGrid)
		idx += (rxyz[k] - szGrid) * mul;
	      else
		idx += rxyz[k] * mul;

	      mul2 *= 2;
	      mul *= szGrid;
	    }

	  assert(rel_mass > 0);
	  assert(rel_mass < 1);
	  assert(idx < totalSize);
	  densityGrid[idx] += rel_mass * particles[i].mass;
	  tot_mass += rel_mass;
	}
      assert(tot_mass < 1.1);
      assert(tot_mass > 0.9);
    }
#endif
#if 0  
  for (uint32_t i = 0; i < N; i++)
    {
      Coordinates xyz;
      int32_t ixyz[NUMDIMS];
      for (int j = 0; j < NUMDIMS; j++)
	{
	  xyz[j] = (particles[i].coords[j] / spatialLen * szGrid);
	  ixyz[j] = (int32_t)round(xyz[j] - 0.5);
	  if (ixyz[j] < 0)
	    ixyz[j] = szGrid-1;
	  else if (ixyz[j] >= szGrid)
	    ixyz[j] = 0;
	}

      uint32_t idx = ixyz[0] + ixyz[1] * szGrid + ixyz[2] * szGrid * szGrid;
      densityGrid[idx] += particles[i].mass;      
    }

#endif

  for (uint32_t i = 0; i < N; i++)
    {
      CICType x, y, z;
      int32_t ix, iy, iz;
      int32_t ix2, iy2, iz2;

      x = particles[i].coords[0] / spatialLen * szGrid + 0.5;
      y = particles[i].coords[1] / spatialLen * szGrid + 0.5;
      z = particles[i].coords[2] / spatialLen * szGrid + 0.5;

      if (x < 0)
	x += szGrid;
      if (y < 0)
	y += szGrid;
      if (z < 0)
	z += szGrid;

      ix = ((int32_t)floor(x));
      iy = ((int32_t)floor(y));
      iz = ((int32_t)floor(z));
      
      ix2 = (ix + 1) % szGrid;
      iy2 = (iy + 1) % szGrid;
      iz2 = (iz + 1) % szGrid;

      CICType alpha_x = x - ix;
      CICType alpha_y = y - iy;
      CICType alpha_z = z - iz;

      ix %= szGrid;
      iy %= szGrid;
      iz %= szGrid;
      
      assert(alpha_x >= 0);
      assert(alpha_y >= 0);
      assert(alpha_z >= 0);

      CICType beta_x = 1 - alpha_x;
      CICType beta_y = 1 - alpha_y;
      CICType beta_z = 1 - alpha_z;

      assert(beta_x >= 0);
      assert(beta_y >= 0);
      assert(beta_z >= 0);

      CICType mass = particles[i].mass;
      uint32_t idx;

      // 000
      idx = ix + (iy + iz * szGrid) * szGrid;
      densityGrid[idx] +=
	mass * beta_x * beta_y * beta_z;
      
      // 100
      idx = ix2 + (iy + iz * szGrid) * szGrid;
      densityGrid[idx] +=
	mass * alpha_x * beta_y * beta_z;
      
      // 010
      idx = ix + (iy2 + iz * szGrid) * szGrid;
      densityGrid[idx] +=
	mass * beta_x * alpha_y * beta_z;
      
      // 110
      idx = ix2 + (iy2 + iz * szGrid) * szGrid;
      densityGrid[idx] +=
	mass * alpha_x * alpha_y * beta_z;

      // 001
      idx = ix + (iy + iz2 * szGrid) * szGrid;
      densityGrid[idx] +=
	mass * beta_x * beta_y * alpha_z;

      // 101
      idx = ix2 + (iy + iz2 * szGrid) * szGrid;
      densityGrid[idx] +=
	mass * alpha_x * beta_y * alpha_z;

      // 011
      idx = ix + (iy2 + iz2 * szGrid) * szGrid;
      densityGrid[idx] +=
	mass * beta_x * alpha_y * alpha_z;

      // 111
      idx = ix2 + (iy2 + iz2 * szGrid) * szGrid;
      densityGrid[idx] +=
	mass * alpha_x * alpha_y * alpha_z;
    }
}
  
void CICFilter::getDensityField(CICType*& field, uint32_t& res)
{
  field = densityGrid;
  res = totalSize;
}