#include "rmannotes.sl"

displacement glassblock(float freq = 2, Km = .065)
{

  float surface_mag, layer_mag;
  float ss, tt;
  point diff_N, tmpP;

  surface_mag = 1;

/* texture blocks */
  ss = repeat(s, freq);
  tt = repeat(t, freq);
  layer_mag = texture("glassblock.tx", ss,tt);
  surface_mag += layer_mag;

  diff_N = normalize(N) - normalize(Ng);
  P += -Km * surface_mag * normalize(N);
  N = normalize(calculatenormal(P)) + diff_N;
}