   }
 
   // World chosen affects iteration parameters.
-  if(w)D=vec4(.05,.0,.98,.022);
+  if(w)
+  {
+    march_params = vec4(0.05, 0.0, 0.98, 0.022);
+  }
 
-  n=T(p,d,D.w,P,N);
+  n = T(p, d, march_params.w, P, N);
   if(.0<n)
   {
     if(w)q=max(dot(L,N),.0)*mix(vec3(.3,.6,.9),vec3(1),smoothstep(-24.,9.,P.y))+pow(max(dot(d,reflect(L,N)),.0),7.)*.11;
     else
     {
-      e=T(P+L*.5,L,D.w*3.,q,q);
+      e =T(P + L * 0.5, L, march_params.w * 3.0, q, q);
       q=(1.-e)*(max(dot(L,N),.0)*mix(vec3(.8,.6,.4),vec3(1),smoothstep(-24.,9.,P.y))+pow(max(dot(d,reflect(L,N)),.0),7.)*.11);
     }
     r=P-v[8];

  return c;
}

float T(vec3 p,vec3 d,float I,out vec3 P,out vec3 N)
{
  vec3 n,r;
  float a=f(p),c,e,i=1.;
  for(;i>.0;i-=I)
  {
    n=p+d*max(a*D.z,.02);
    c=f(n);
    if(.0>c)
    {

#version 430

layout(location=0)uniform sampler2D surface_texture;
layout(location=1)uniform sampler3D noise_volume;
layout(location=2)uniform vec3[10] v;
#if defined(USE_LD)
layout(location=19)uniform mat3 m;
