surface
KTtreeS
(
float      Ka=1,Kd=1,Ks=0.2,roughness=0.8;
float      octaves=8,lambda=2;
float     scale=40,mag=0.005;
/*color     cs1=color(0.42,0.388,0.29),cs2=color(0.65,0.568,0.42)*/
color     cs1=color(0.35,0.33,0.29),cs2=color(0.7,0.65,0.5)
)

{
float     i,value,freq;
float    littlemag;
point    PP,Nf,V,PT;
color    cs;

PP=transform("object",P);
PT=PP*scale;

value=0;
freq=1;
for (i=1;i<octaves;i+=1) {
/*    value+=(2*noise(PT)-1)/freq;*/
    value+=(2*noise(PT+2*noise(point(PT))-point(1,1,1))-1)/freq;
    PT*=freq;
    freq*=lambda;
}

value+=1;
value/=2;
cs=mix(cs1,cs2,value);

/*littlemag=(1-smoothstep(0,0.5,value))-smoothstep(0.5,1,value);*/
littlemag=(1-smoothstep(0,0.25,value))-smoothstep(0.75,1,value);
littlemag*=mag;
N=calculatenormal(P+littlemag*normalize(N));

Nf=faceforward(normalize(N),I);
V=normalize(-I);
Ci=cs*(Ka*ambient()+Kd*diffuse(Nf)+Ks*specular(Nf,V,roughness));

}