/****************************************************************************
* superplank.sl -- another surface shader for wood planks.
*
* Description:
* Makes texture of wooden planks in s-t space. This wood looks rather
* like varnished oak planks, with staggered planks, rings and grain,
* reflections (either traced or via reflection map), and bumps.
* It can make the plank pattern as either straight staggered planks
* or in a parquet pattern.
*
* Parameters:
* Ka, Kd, Ks, specularcolor, roughness - work just like the plastic shader
* Kr, eta - reflection amount and index of refraction (for fresnel)
* Ktrace, Krefl, reflmap - const for trace, for refl map, filename
* txtscale - overall scaling factor for the texture
* Km - overall scaling factor for bumpiness.
* lightwood - wood-like color from which the various shades are derived.
* plankwidth - width of each plank (in terms of s/t)
* planklength - length of each plank (in terms of s/t)
* groovewidth - width of the grooves between the planks (in terms of s/t)
* groovedepth - depth of the groove indentations (in shader space units)
* groovecolor - the color of the "grooves" between the planks
* plankpattern - plank orientation pattern 1=straight, 2=parquet
* plankspertile - for parquet, number of sub-planks
* plankstagger - for staggered, how much are the rows of planks staggered
* plankvary - controls how much wood color varies from plank to plank
* ringscale - scaling for the ring spacing
* ringwidth - relative width of the dark ring parts
* wavy - relative wavyness of the ring pattern
* grainy - relative graininess (0 = no fine grain)
* grainscale - scaling for the fine grain
* graindepth - depth of grain and ring grooves
* varnishbumpfreq - frequency of bumps in the varnish coating
* varnishbumpamp - height of bumps in the varnish coating
*
* Antialiasing: this shader does a pretty good job of antialiasing itself,
* even with low sampling densities.
*
* Author: written by Larry Gritz
* current contact address: gritzl@acm.org
*
* $Revision: 1.6 $ $Date: 1997-11-23 17:36:25-08 $
*
****************************************************************************/
#include "noises.h"
#include "patterns.h"
#define MINFILTERWIDTH 1.0e-7
/* Estimate the filter width -- i.e. the change from pixel to pixel -- of
* float and point values.
*/
#define filterwidth(x) (abs(Du(x)*du) + abs(Dv(x)*dv))
surface
superplank (/* Parameters: */
/* BRDF */
float Ka = 1, Kd = 1; /* Overall ambient & diffuse response */
float Ks = .75, roughness = .02; /* Spec highlight control */
color specularcolor = 1; /* Spec reflection color */
float Kr = 1, eta = 1.5; /* Mirror refl & index of refr */
float Ktrace = 1, Krefl = 0; /* trace and reflection map */
string reflmap = "";
/* Overall texturing control */
float txtscale = 1; /* Overall scaling factor */
float Km = 1; /* Overall bumpiness factor */
color lightwood = color (.5, .2, .067); /* light wood color */
/* Plank layout */
float plankpattern = 1; /* 1=straight, 2=parquet */
float plankspertile = 4; /* For parquet */
float plankwidth = .05; /* Width of a plank */
float planklength = .75; /* Length of a plank */
float groovewidth = 0.001; /* Width of the grooves between planks */
float groovedepth = .0004; /* Depth of the groove */
color groovecolor = color (.01, .003, .001);
float plankstagger = 1; /* How much should rows be staggered */
float plankvary = 0.8; /* Wood color variation plank-to-plank */
/* Wood appearance */
float ringscale = 25; /* Larger makes more, thinner rings */
float ringwidth = 1; /* Relative ring width */
float wavy = 0.08; /* Larger makes rings more wavy */
float grainy = 1; /* Relative graininess */
float grainscale = 60; /* Larger makes smaller "grains" */
float graindepth = 0.0001; /* Depth of divots where grains are */
float varnishbumpfreq = 30; /* Bump freq of the varnish */
float varnishbumpamp = 0.0003; /* How big are the varnish bumps? */
)
{
/* mapping coordinates */
float ss, tt;
float grain_s, grain_t, ring_s, ring_t, plank_s, plank_t;
/* antialiasing */
float swidth, twidth, fwidth;
float sw, tw, overallscale;
/* Planks & grooves */
uniform float PGWIDTH, PGHEIGHT, GWF, GHF;
float whichrow, whichplank; /* Index for each row & plank within row */
float w, h; /* temporaries */
float groovy; /* 0 in groove, 1 in woody part */
/* Wood appearance */
color Ct, woodcolor;
float r2;
float fade, ttt;
float ring; /* 1 in a ring darkening, 0 where not */
float grain; /* 1 inside a grain bit, 0 elsewhere */
/* Illumination model */
float adjustedKs;
vector IN; /* normalized I vector */
normal NN; /* normalized N for displacing */
normal Nf; /* forward facing, normalized normal */
vector R, T_dummy; /* Refl (and tummy transmit) from fresnel */
float fresnelKr, fresnelKt; /* Fresnel reflection coefficients */
float shadlen; /* length of a unit of shader space */
float disp; /* accumulate displacement here */
point Pndc; /* NDC coordinate of P */
vector V;
color Cspec;
float nonspec;
float tmp;
/*
* 1. Setup.
*
* Determine the basic mapping, filter sizes for antialiasing, other
* values used throughout the shader.
*/
/* First, determine the basic mapping */
ss = s * txtscale;
tt = t * txtscale;
/* Compute the basic filter size for antialiasing */
swidth = max (filterwidth(ss), MINFILTERWIDTH);
twidth = max (filterwidth(tt), MINFILTERWIDTH);
fwidth = max (swidth,twidth);
/* How much current space corresponds to a unit of s or t?
* We will use this later to help scale the displacement, this making
* the bumps scale relative to the overall pattern, rather than being
* strictly tied to the scale of the object.
*/
overallscale = (length(Deriv(P,ss)));
/*
* 2. Plank pattern.
*
* Determine which row and plank we're on, and come up with an
* antialiased term for whether we're in or out of a groove.
*/
if (plankpattern == 1) {
/* Straight, staggered planks */
PGWIDTH = plankwidth + groovewidth;
PGHEIGHT = planklength + groovewidth;
plank_s = ss / PGWIDTH;
whichrow = floor (plank_s);
/* Jiggle each row */
plank_t = tt / PGHEIGHT + 20 * plankstagger * cellnoise(whichrow);
whichplank = floor(plank_t);
} else {
/* Parquet pattern */
PGWIDTH = plankwidth + groovewidth;
PGHEIGHT = PGWIDTH * plankspertile;
plank_s = ss / PGWIDTH;
whichrow = floor (plank_s);
plank_t = tt / PGHEIGHT;
whichplank = floor(plank_t);
if (mod ((whichrow/plankspertile) + whichplank, 2) >= 1) {
plank_s = tt / PGWIDTH;
plank_t = ss / PGHEIGHT;
whichrow = floor (plank_s);
whichplank = floor(plank_t);
tmp = ss; ss = tt; tt = tmp;
tmp = swidth; swidth = twidth; twidth = tmp;
}
}
/* Now whichplank is a unique integer index for each plank */
/* Figure out where the grooves are. The value groovy is 0 where there
* are grooves, 1 where the wood grain is visible. Do some simple
* antialiasing by trying to box filter the edges of the grooves.
*/
/* compute half width & length of groove as fraction of plank size */
GWF = groovewidth*0.5/PGWIDTH;
GHF = groovewidth*0.5/PGHEIGHT;
sw = swidth / PGWIDTH;
tw = twidth / PGHEIGHT;
if (sw >= 1)
w = 1-2*GWF; /* Filter width is wider than the plank itself */
else w = filteredpulse (whichrow+GWF, whichrow+1-GWF, plank_s, sw);
if (tw >= 1)
h = 1 - 2*GHF; /* Filter width is longer than the plank itself */
else h = filteredpulse (whichplank+GHF, whichplank+1-GHF, plank_t, tw);
groovy = w*h;
/*
* 3. Ring and grain patterns, color and specularity adjustment.
*
* The wood has rings at one scale, grain at a finer scale. They
* interact subtly.
*/
/* Compute the filter width first, so we don't bother with more if
* the rings are too small to see.
*/
fwidth = max (swidth*ringscale, twidth*ringscale);
fade = smoothstep (.75, 4, fwidth);
if (fade < 0.999) {
ring_s = ss * ringscale;
ring_t = tt * ringscale;
ttt = ring_t + whichplank*28.38 + wavy * noise (8*ring_s, ring_t);
ring = ringscale * noise (ring_s-whichplank*4.18, ttt/20);
ring -= floor (ring);
ring = 0.3 + 0.7 * smoothstep(.55-.35*ringwidth, 0.55, ring) *
(1 - smoothstep(0.75, 0.8, ring));
ring = (1-fade)*ring + 0.65*fade;
/* Grain pattern */
fwidth = max (swidth*grainscale, twidth*grainscale);
fade = smoothstep (.75, 4, fwidth);
if (fade < 0.999) {
grain_s = ss * grainscale;
grain_t = tt * grainscale;
r2 = 1.3 - noise (12*grain_s, grain_t);
r2 = grainy * r2*r2 + (1-grainy);
grain = (1-fade)*r2 + (0.75*fade);
}
else
grain = 0.75;
}
else {
ring = 0.4875;
grain = 0.75;
}
grain *= (.85 + .15*ring);
/* Start with the light wood color */
woodcolor = lightwood;
/* Add some plank-to-plank variation in overall color */
woodcolor *= 1 - plankvary/2
+ plankvary * float cellnoise (whichplank,whichrow);
/* Darken the wood according to the ring and grain patterns */
woodcolor *= (1 - 0.25*ring) * (1-.5*grain);
/* Combine the rings, grain, plank variation into one surface color */
Ct = mix (groovecolor, woodcolor, groovy);
/* Less specular in the grooves, more specular in the dark wood. */
adjustedKs = Ks * (1 + .2*ring) * (1 + .3*grain) * groovy;
/*
* 4. Bumps
*
* We do some bump mapping to make the grooves and grain depressed,
* and add some general lumpiness to the varnish layer.
*/
if (Km > 0) {
/* Grooves */
disp = -groovedepth * (1-groovy);
/* Random bumps on the varnish */
if (varnishbumpamp > 0)
disp += varnishbumpamp *
(2*noise(varnishbumpfreq*ss,varnishbumpfreq*tt) - 1);
/* Depressions due to grain & rings */
disp -= graindepth * (.75*grain + ring);
/* Find out how long a unit of shader space is, in current units */
NN = normalize(N);
shadlen = overallscale/length (ntransform("shader",NN));
/* Recalculate N */
N = calculatenormal (P + (Km * shadlen * disp) * NN);
}
/*
* 5. BRDF
*
* The wood itself behaves like plastic, the varnish overtop reflects
* using the fresnel formula (grazing angles reflect like mirrors).
* Have some subtle interaction between grain and specularity.
*/
IN = normalize(I);
V = -IN;
Nf = faceforward (normalize(N),I);
fresnel (IN, Nf, 1/eta, fresnelKr, fresnelKt, R, T_dummy);
fresnelKr *= Kr;
Cspec = 0;
illuminance (P, Nf, PI/2) {
nonspec = 0;
lightsource ("__nonspecular", nonspec);
if (nonspec < 1) {
vector H = normalize(normalize(L)+V);
Cspec += Cl * ((1-nonspec) * smoothstep (.6, .85, pow(max(0,Nf.H), 8/roughness)));
}
}
Ci = (1-fresnelKr) * (Ct * (Ka*ambient() + Kd*diffuse(Nf)))
+ adjustedKs * (specularcolor * Cspec);
/* Only compute reflections if Kr > 0 */
if (fresnelKr > 0.001) {
if (Krefl > 0 && reflmap != "") {
Pndc = transform ("NDC", P);
Ci += fresnelKr * specularcolor *
texture (reflmap, xcomp(Pndc), 1-ycomp(Pndc));
}
if (Ktrace > 0)
Ci += Ktrace * fresnelKr * specularcolor * trace (P, R);
}
/* Scale by opacity */
Oi = Os;
Ci *= Oi;
}