/*
 * Barnacle color shader
 * Peter Stuart
 * $Id: barncolor.sl,v 1.2 2003/11/18 19:01:39 ophi Exp $
 * description: Colors barnacles. The barnacles are drawn on a crappy
 * "wood-like" background. The shading model used is similar to plastic
 * with Kd=0.8, Ks=0.3, and spec=0.05.
 * Accompanies barndisp.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
 *
 * ---- surface parameters ----------------
 * basecolor: color of background "wood-like" shader (used instead of Cs)
 * Ka: ambient value
 */

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

#pragma hint "basecolor" color

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

#define bomb_params uniform float ncones, sparse, variation, seed;	\
  output color barn_color; output float barn_opac;
#define use_bomb_params ncones, sparse, variation, seed, barn_color, barn_opac

void barnaclecolor(float s, t, sfreq, tfreq, col, row, bomb; bomb_params)
{
  float xs, xt;
  color layer_color;
  float layer_opac;
  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_color = draw_barnacle_color(ncones, barnrad2, barnrad1, 0.05,
					(seed+RN(299287))*noise(col+RN(42),
								row+RN(42)),
					xs, xt, layer_opac);
      
      barn_color = blend(barn_color, layer_color, layer_opac);
      barn_opac = union(layer_opac, barn_opac);
    }
}

#define bomb_func barnaclecolor
#include "bomber.h"

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

surface barncolor(float ncones=6;
		  float sfreq=20, tfreq=10;
		  float sparse=0, variation=5;
		  float seed = 1299;
		  color basecolor = 1;
		  float Ka = 0.1;)
{
  color layer_color, surface_color;
  float layer_opac, barn_opac;
  color barn_color;

  barn_color = 0;
  barn_opac = 0;
  surface_color = 0;

  normal Nf = faceforward (normalize(N),I);

  /********* base **********************************/
  surface_color = basecolor;

/*   layer_color = basecolor; */

  /* HACK: for some reason either shaderdl or vcc will have a problem
     seeing that the following code is a float, and casting doesn't work
     in both cases. */
/*   float bloody_hack = (t+snoise(s*40 + RN(44251)))*20 + RN(6672); */
/*   layer_opac = noise(bloody_hack); */

/*   layer_color = layer_color * (Ka*ambient() + 0.3*diffuse(Nf)) */
/*     + 0.8*layer_opac*specular(Nf, -normalize(I), 0.05); */
/*   surface_color = blend(surface_color, layer_color, layer_opac); */

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

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

  /* barnacle lighting */
  barn_color = barn_color * (Ka*ambient() + 0.5*diffuse(Nf))
    + 0.5*specular(Nf, -normalize(I), 0.1);
  surface_color = blend(surface_color, barn_color, barn_opac);

  Ci = surface_color;

}