/*  Rick Grandy */

#include "rmannotes.sl"

surface onk2(color grey = color (.8, .8, .8);
	    float Ka = 1, Ks = 1, roughness = 0.15;
	    string texname = "brick.tex")

{
	color paper, ink, map;
	float opac;
	float fuzz, d, wide, wide2, wide3, wide4, wide5, vertline, horzline;
	float tile_s, tile_t;
	point a,b, c,e, f,g, h,i, j,k, l,m, n,o, p,q, w,x, y,z, Nf,V;
	color black = color(0,0,0);
	fuzz = .03;

	Nf = faceforward(normalize(N), I);
	V = normalize(-I);

	paper = black;
	Oi = 0;
	wide = .15;
	wide2 = .1;
	wide3 = .225;
	wide4 = .3;
	wide5 = .125;

	a = (.5, .5, 0);
	b = (.5, 1, 0);

	c = (0, .5, 0);
	e = (1, .5, 0);
	
	f = (.1, .1, 0);
        g = (.9, .1, 0);
	
	h = (.1, .37, 0);
	i = (.9, .37, 0);

	j = (.1, .65, 0);
	k = (.3, .65, 0);

	l = (.7, .65, 0);
	m = (.9, .65, 0);

	n = (.5, .2, 0);
	o = (.5, .3, 0);
	
	p = (.5, .195, 0);
	q = (.5, .325, 0);
	
	w = (.35, .66, 0);
	x = (.35, .9, 0);

	y = (.65, .66, 0);
	z = (.65, .9, 0);

	tile_s = repeat(s, 2);
	tile_t = repeat(t, 1);


/* Vertical Line (a,b) */

	ink = grey;
	d = ptlined(a, b, (tile_s, tile_t, 0));
	vertline = 1 - smoothstep(wide - fuzz,wide + fuzz, d);
	paper = mix(paper, ink, vertline);
	Oi = mix(Oi, grey, vertline);      

/* Horizontal line (c,e) */
	
	ink = grey;
	d = ptlined(c, e, (tile_s, tile_t, 0));
	horzline = union(vertline, 1 - smoothstep(wide - fuzz,wide + fuzz, d));
	paper = mix(paper, ink, horzline);
	Oi = mix(Oi, grey, horzline);

/* Hor-line reduce #1 (h,i) */

	ink = black;
	d = ptlined(h, i, (tile_s, tile_t, 0));
	opac = 1 - smoothstep(wide2 - fuzz,wide2 + fuzz, d);
	paper = mix(paper, ink, opac);
	Oi = mix(Oi, black, opac);

/* Hor-line reduce #2 (j,k) */

	ink = black;
	d = ptlined(j, k, (tile_s, tile_t, 0));
	opac = 1 - smoothstep(wide2 - fuzz,wide2 + fuzz, d);
	paper = mix(paper, ink, opac);
	Oi = mix(Oi, black, opac);

/* Hor-line reduce #3 (l,m) */

	ink = black;
	d = ptlined(l, m, (tile_s, tile_t, 0));
	opac = 1 - smoothstep(wide2 - fuzz,wide2 + fuzz, d);
	paper = mix(paper, ink, opac);
	Oi = mix(Oi, black, opac);     

/* Vert-line reduce #1 (w,x) */

	ink = black;
	d = ptlined(w, x, (tile_s, tile_t, 0));
	opac = 1 - smoothstep(wide2 - fuzz,wide2 + fuzz, d);
	paper = mix(paper, ink, opac);
	Oi = mix(Oi, black, opac);

/* Vert-line reduce #2 (y,z) */

	ink = black;
	d = ptlined(y, z, (tile_s, tile_t, 0));
	opac = 1 - smoothstep(wide2 - fuzz,wide2 + fuzz, d);
	paper = mix(paper, ink, opac);
	Oi = mix(Oi, black, opac);

/* Grey oval (p,q) */

	ink = grey;
	d = ptlined(p, q, (tile_s, tile_t, 0));
	opac = 1 - smoothstep(wide3 - fuzz,wide3 + fuzz, d);
	paper = mix(paper, ink, opac);
	Oi = mix(Oi, grey, opac);	

/* Inner oval (n,o) */

	ink = black;
	d = ptlined(n, o, (tile_s, tile_t, 0));
	opac = 1 - smoothstep(wide5 - fuzz,wide5 + fuzz, d);
	paper = mix(paper, ink, opac);
	Oi = mix(Oi, black, opac);	

/* Texture */

	map = texture(texname, tile_s, tile_t);
	paper = mix(paper, map, opac);
	Oi = mix(Oi, map, opac);

	Ci = Oi *paper*map* (Ka * ambient() + Ks * specular(Nf, V, roughness));
}