/* c3d-accumf.c
 *
 * COPYRIGHT (c) 2010 The Diderot Project (http://diderot.cs.uchicago.edu)
 * All rights reserved.
 *
 * Single-precision accumulator version.
 */

#include <stdio.h>
#include <math.h>

#define IMG_SZ 11

float V[IMG_SZ][IMG_SZ][IMG_SZ];		// image data
float h[4][4] = {		// bspln3
	{ 1.33333,   2.0,  1.0,  0.166667 },   // -2 .. -1
	{ 0.666667,  0.0, -1.0, -0.5 },        // -1 .. 0
	{ 0.666667,  0.0, -1.0,  0.5 },        //  0 .. 1
	{ 1.33333,  -2.0,  1.0, -0.166667 },   //  1 .. 2
};
const int s = 2;       // kernel support

float probe (float x[3]) { 
  float nxd, nyd, nzd, fx, fy, fz;
  int nx, ny, nz;

  fx = modff (x[0], &nxd); nx = (int)nxd;
  fy = modff (x[1], &nyd); ny = (int)nyd;
  fz = modff (x[2], &nzd); nz = (int)nzd;

  // compute kernel values for each axis
  float hx[4], hy[4], hz[4];
  for (int i = 1-s;  i <= s;  i++) {
    float t;
    t = fx - i;
    hx[i+s-1] = h[s-i][0] + t*(h[s-i][1] + t*(h[s-i][2] + t*h[s-i][3]));
    t = fy - i;
    hy[i+s-1] = h[s-i][0] + t*(h[s-i][1] + t*(h[s-i][2] + t*h[s-i][3]));
    t = fz - i;
    hz[i+s-1] = h[s-i][0] + t*(h[s-i][1] + t*(h[s-i][2] + t*h[s-i][3]));
  }

  float vx = 0.0;
  for (int i = 1-s;  i <= s;  i++) {
    float vy = 0.0;
    for (int j = 1-s;  j <= s;  j++) {
      float vz = 0.0;
      for (int k = 1-s;  k <= s;  k++) {
      	vz += V[nx+i][ny+j][nz+k] * hz[k+s-1];
      }
      vy += vz * hy[j+s-1];
    }
    vx += vy * hx[i+s-1];
  }

  return vx;
}

#define AIR_AFFINE(i,x,I,o,O) ( \
((float)(O)-(o))*((float)(x)-(i)) / ((float)(I)-(i)) + (o))

int
main() {
  int I, J, K, N;
  float P[3];

  V[5][5][5] = 1.0;
  N=60;
  for (I=0; I<N; I++) {
    P[0] = AIR_AFFINE(0, I, N, 2.0001, 7.9999);
    for (J=0; J<N; J++) {
      P[1] = AIR_AFFINE(0, J, N, 2.0001, 7.9999);
      for (K=0; K<N; K++) {
        P[2] = AIR_AFFINE(0, K, N, 2.0001, 7.9999);
        printf("%g\n", probe(P));
      }
    }
  }

  return 0;
}