/*
 * Barnacle displacement shader
 * Peter Stuart
 * $Id: barndisp.sl,v 1.3 2003/11/18 19:01:40 ophi Exp $
 * description: Displaces barnacles. Accompanies barncolor.sl
 *
 * ---- common parameters ----------------
 * ncones: number of bulges in barnacle.
 * sfreq, tfreq: number of barnacles in s and t
 * sparse: control sparseness of barnacles across surface. The value is
 *    interpreted as follows:
 *      0 - appear all over surface
 *      0.5 - appear with density determined by the density function
 *      1 - appear nowhere
 *    values in between are interpolated.
 * variation: controls the frequency of a simple perlin noise function
 *    that controls the density of the barnacles.
 * seed: controls random attributes
 *
 * ---- displacement parameters ----------
 * max_height: height of barnacles. Adjusted automatically based on frequency.
 * spikiness: length of spikes on top ridge of barnacle
 */

#include "sl2vex.h"
#include "barnacle.h"

/************** set up bombing ******************************/

#define bomb_params uniform float max_height, ncones, spikiness,	\
    sparse, variation, seed; output float barn_disp;

#define use_bomb_params max_height, ncones, spikiness,	\
    sparse, variation, seed, barn_disp


void barnacledisp(float s, t, sfreq, tfreq, col, row, bomb; bomb_params)
{
  float xs, xt;
  float layer_disp;
  float barnrad1 = 0.5;
  float barnrad2 = 0.1;

  if (test_and_xform(s, t, sfreq, tfreq, col, row,
		     bomb, sparse, variation, seed,
		     xs, xt) != 0)
    {
      layer_disp = draw_barnacle_displace(ncones, spikiness,
					  barnrad2, barnrad1, 0.05,
			     (seed+RN(299287)) * noise(col+RN(42), row+RN(42)),
					  xs, xt);
      
      barn_disp = max(max_height*layer_disp/max(sfreq, tfreq), barn_disp);
    }
}

#define bomb_func barnacledisp
#include "bomber.h"

/******************* shader **************************************/

displacement barndisp(float max_height=0.2, ncones=6, spikiness=0.5;
		      float sfreq=20, tfreq=10;
		      float sparse=0, variation=5;
		      float seed = 1299)
{
  float barn_disp = 0;

  /********** barnacles ****************************/

  bomber(s, t, sfreq, tfreq, use_bomb_params);

  /* barnacle displacement */
  vector Nn = normalize(N);
  P += Nn * (barn_disp / length(shader_space(Nn)));
  N = calculatenormal(P);
}