sandbox/Antoonvh/itmov.c

    The tree-grid iterator

    The page draws the cell-iterator movie

    We use Bview to draw the process of grid-iteration

    #include "view.h"

    We visualize scalar field s as the iterator progresses.

    int base_lev = 4, n, jj, nmin;
scalar s[];

    Each iteration we will draw a frame with all the cells and the s field.

    void draw_frame(char * fname){
  cells();
  squares ("s", min = 0, max = n);
  save (fname);
}

int main(){

    We define a camera-centered grid with some refinement features

      X0 = Y0 = -L0/2;
  init_grid (1 << base_lev);
  refine (fabs(x + y) < 0.2 && level <= base_lev);
  refine (sq(x - 0.25) + sq(y - 0.25) < sq(0.1) && level < base_lev + 2);

    We unset the data stored in s and count the number of cells for each thread.

      foreach(){
    s[] = nodata;
    n++;
  }

    For _MPI, each thread should help draw the same number of frames. therefore, the maximum number of cells is communicated between the processor ranks.

    #if _MPI
  MPI_Allreduce (&n, &nmin, 1, MPI_INT, MPI_MIN, MPI_COMM_WORLD);
  MPI_Allreduce (MPI_IN_PLACE, &n, 1, MPI_INT, MPI_MAX, MPI_COMM_WORLD);
  printf("%d %d %d\n", pid(), n, nmin);
  //balance(); //<- This is already in `refine()`
#endif

    We loop over the cells and per iteration we increase the value of s.

      view (fov = 20);
  draw_frame("s.mp4");
  foreach(){
    s[] = jj;
    draw_frame("s.mp4");
    if (jj++ == nmin - 1 && nmin != 0)
      draw_frame("unbalanced.png");
  }

    and continue untill all threads are finished.

      if (jj < n){
    draw_frame("s.mp4");
    jj++;
  }
}
    White cell(s) indicate an unbalance

    White cell(s) indicate an unbalance