Hackers Magazine 57/CdHackersMagazineNr57.iso/Software/Multimedia/k3d-setup-0.7.11.0.exe/share/k3d/shaders/surface/k3d_tooledsteel.sl

Text File | 2008-01-23 | 4.3 KB | 169 lines

/*  tooledsteel.sl written 9/99 by Ivan DeWolf
 *  ivan@SpamSucks_martian-tools.com
 *  feel free to copy, distribute, hack and/or abuse this code
 *  in any way you see fit, but please leave my name near the top
 *
 *  a combination of IDbrushedmetal.sl and the Worley-esque
 *  F1 from bubbly.sl adapted to happen in parameter space.
 *  A vector is computed from the gradient of the distance function,
 *  and then used as the vector of anisotropy. works best on parametric
 *  surfaces where you don't care about the seams.
 *  (like that'll ever happen...)
 *  thanks to Jos Stam whose animated cube motivated this thing.
 *
 *
 *  PARAMETERS:
 *  mult            - multiples of swirls per unit
 *  Nzscale         - scale of the noise that randomizes the location of
 *                    the swirls. set this to zero for a perfect grid.
 *  Ks            - coefficient of specular
 *  Kd            - coefficient of diffuse
 *  Ka            - coefficient of ambient
 *  Kr            - coefficient of reflectivity
 *  specwidth        - the width of the specular stripe
 *               maxes out at 10
 *  specspread        - the spread of the specular stripe
 *              maxes out at .5
 *  mapspread        - the spread of the reflection map streaking
 *              maxes out at .5
 *  twist        - allows you to twist the direction of anisotropy
 *              angle in radians (i.e. PI*.5 = 90 degrees)
 *  mapname        - name of the environment map
 *  specularcolor    - color of the specular hilight
 */

vector
getvec(float  mult; float Nzscale)
{
  extern point P;
  extern vector dPdu;
  extern vector dPdv;
  extern float s;
  extern float t;
  vector udir = vector(1,0,0);
  vector vdir = vector(0,1,0);

  float a,b,c;
  float dist, shortest=10000;
  float valu,valv;
  point Po = point(s*mult,t*mult,0);
  point Pou = Po +(udir*.01);
  point Pov = Po +(vdir*.01);

  /*true cell center, surrounding cell centers, noised cell center*/
  point trucell, surrcell, nzcell;
  vector offset, nzoff, out;
  float chu, chv;

  float ncells = floor(mult);
  float cellsize = 1/ncells;

  setxcomp(trucell,floor(xcomp(Po))+.5);
  setycomp(trucell,floor(ycomp(Po))+.5);
  setzcomp(trucell,0);
  c = 0;

  /*what is the shortest distance to a noised cell center?*/
  for(a = -1; a<= 1; a+=1){
    for(b = -1; b<=1; b += 1){
    offset = vector(a,b,c);
    surrcell = trucell+offset;
    nzoff = ((vector cellnoise(surrcell)-.5)*Nzscale);
    setzcomp(nzoff,0);
    nzcell = surrcell + nzoff;
    dist = distance(Po,nzcell);
    if(dist<shortest){
      shortest = dist;
      valu = distance(Pou,nzcell);
      valv = distance(Pov,nzcell);
    }
    }
  }
  chu = valu - shortest;
  chv = valv - shortest;
  out  = normalize((udir*chu)+(vdir*chv));
  return out;
}

color
anisospecular (vector VA; float specspread; float specwidth)
{

    extern vector I;
    extern normal N;
    extern point P;

    float nonspec;
    vector V = normalize(-I);
    normal NN = normalize(N);
    normal Nf = faceforward(NN,-V);
    color pixbrdf, C = 0;
    point zro = 0;

    illuminance (P, Nf, PI*.5) {
        extern vector L;
    extern color Cl;

        nonspec = 0;
        lightsource ("__nonspecular", nonspec);
        if (nonspec < 1) {
            vector LN = normalize (L);
        vector H = normalize (V + LN);

        pixbrdf  = specularbrdf(LN, Nf,V,specspread);
            C += Cl * pixbrdf * pow( 1-abs(VA.H), 1/specwidth );

        }
    }
    return C;
}

surface
k3d_tooledsteel(
    float    mult        =  3,
        Nzscale        =  1.5,
        Ks        =  1,
        Kd        = .01,
        Ka        = .001,
        Kr        = .6,
        specwidth    = .5,
        specspread     = .5,
        mapspread     = .2,
        twist        =  0;
    string    mapname     = "";
    color    specularcolor    =  1)
{
        vector VA = getvec(mult,Nzscale);
    point Po = transform("object",P);
    color ev = 0;
    vector D, V= normalize(-I);
    vector Nf, Ntmp;
        point zro = 0;
    float i, numsamples = 20;
    float angle, jitter;
    float Jspread = PI*(1/numsamples)*mapspread;

    VA = rotate(VA, twist, zro, normalize(N));


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

    if( mapname != "" ) {
        for(i=0;i<=numsamples;i=i+1){
          jitter = (random()-.5)*Jspread;
          angle = PI*((i/numsamples)-.5)*mapspread;
          Ntmp = rotate(Nf,angle+jitter,zro,VA);
          D = reflect(-V, Ntmp);
          D = vtransform("world", D);
          ev += environment(mapname, D)*(.5-abs((i/numsamples)-.5))*.25;
        }
    } else
        ev = 0;

    Oi = Os;
    Ci = Oi * (Cs * (Ka * ambient() + Kd * diffuse(-Nf)) +
    specularcolor * Ks * anisospecular(VA, specspread*2, specwidth*.1)) +
    ev * Kr;
}