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extern double specthresh; /* specular sampling threshold */ |
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extern double specjitter; /* specular sampling jitter */ |
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static gaussamp(); |
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/* |
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* This routine uses portions of the reflection |
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* model described by Cook and Torrance. |
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* The computation of specular components has been simplified by |
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* numerous approximations and ommisions to improve speed. |
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* This routine implements the isotropic Gaussian |
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* model described by Ward in Siggraph `92 article. |
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* We orient the surface towards the incoming ray, so a single |
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* surface can be used to represent an infinitely thin object. |
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* |
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typedef struct { |
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OBJREC *mp; /* material pointer */ |
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RAY *rp; /* ray pointer */ |
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short specfl; /* specularity flags, defined above */ |
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COLOR mcolor; /* color of this material */ |
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COLOR scolor; /* color of specular component */ |
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double omega; /* light source size */ |
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{ |
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double ldot; |
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double dtmp; |
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int i; |
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double dtmp, d2; |
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FVECT vtmp; |
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COLOR ctmp; |
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setcolor(cval, 0.0, 0.0, 0.0); |
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* gaussian distribution model. |
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*/ |
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/* roughness */ |
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dtmp = 2.0*np->alpha2; |
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dtmp = np->alpha2; |
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/* + source if flat */ |
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if (np->specfl & SP_FLAT) |
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dtmp += omega/(2.0*PI); |
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dtmp += omega/(4.0*PI); |
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/* half vector */ |
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vtmp[0] = ldir[0] - np->rp->rdir[0]; |
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vtmp[1] = ldir[1] - np->rp->rdir[1]; |
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vtmp[2] = ldir[2] - np->rp->rdir[2]; |
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d2 = DOT(vtmp, np->pnorm); |
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d2 *= d2; |
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d2 = (DOT(vtmp,vtmp) - d2) / d2; |
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/* gaussian */ |
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dtmp = exp((DOT(np->vrefl,ldir)-1.)/dtmp)/(2.*PI)/dtmp; |
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dtmp = exp(-d2/dtmp)/(4.*PI*dtmp); |
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/* worth using? */ |
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if (dtmp > FTINY) { |
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copycolor(ctmp, np->scolor); |
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dtmp *= omega / np->pdot; |
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dtmp *= omega * sqrt(ldot/np->pdot); |
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scalecolor(ctmp, dtmp); |
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addcolor(cval, ctmp); |
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} |
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* is always modified by material color. |
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*/ |
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/* roughness + source */ |
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dtmp = np->alpha2/2.0 + omega/(2.0*PI); |
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dtmp = np->alpha2 + omega/PI; |
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/* gaussian */ |
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dtmp = exp((DOT(np->prdir,ldir)-1.)/dtmp)/(2.*PI)/dtmp; |
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dtmp = exp((2.*DOT(np->prdir,ldir)-2.)/dtmp)/(PI*dtmp); |
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/* worth using? */ |
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if (dtmp > FTINY) { |
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copycolor(ctmp, np->mcolor); |
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dtmp *= np->tspec * omega / np->pdot; |
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dtmp *= np->tspec * omega * sqrt(-ldot/np->pdot); |
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scalecolor(ctmp, dtmp); |
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addcolor(cval, ctmp); |
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} |
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if (m->oargs.nfargs != (m->otype == MAT_TRANS ? 7 : 5)) |
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objerror(m, USER, "bad number of arguments"); |
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nd.mp = m; |
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nd.rp = r; |
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/* get material color */ |
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setcolor(nd.mcolor, m->oargs.farg[0], |
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m->oargs.farg[1], |
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else |
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setcolor(nd.scolor, 1.0, 1.0, 1.0); |
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scalecolor(nd.scolor, nd.rspec); |
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if (nd.specfl & SP_PURE) { /* improved model */ |
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dtmp = exp(-BSPEC(m)*nd.pdot); |
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for (i = 0; i < 3; i++) |
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colval(nd.scolor,i) += |
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(1.0-colval(nd.scolor,i))*dtmp; |
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nd.rspec += (1.0-nd.rspec)*dtmp; |
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} else if (specthresh > FTINY && /* check threshold */ |
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/* improved model */ |
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dtmp = exp(-BSPEC(m)*nd.pdot); |
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for (i = 0; i < 3; i++) |
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colval(nd.scolor,i) += (1.0-colval(nd.scolor,i))*dtmp; |
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nd.rspec += (1.0-nd.rspec)*dtmp; |
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/* check threshold */ |
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if (!(nd.specfl & SP_PURE) && |
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specthresh > FTINY && |
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(specthresh >= 1.-FTINY || |
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specthresh > nd.rspec)) |
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specthresh + .05 - .1*frandom() > nd.rspec)) |
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nd.specfl |= SP_RBLT; |
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/* compute reflected ray */ |
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for (i = 0; i < 3; i++) |
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/* check threshold */ |
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if (!(nd.specfl & SP_PURE) && specthresh > FTINY && |
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(specthresh >= 1.-FTINY || |
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specthresh > nd.tspec)) |
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> |
specthresh + .05 - .1*frandom() > nd.tspec)) |
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nd.specfl |= SP_TBLT; |
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if (r->crtype & SHADOW || |
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DOT(r->pert,r->pert) <= FTINY*FTINY) { |
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transtest = 2; |
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} else { |
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for (i = 0; i < 3; i++) /* perturb */ |
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< |
nd.prdir[i] = r->rdir[i] - |
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< |
0.5*r->pert[i]; |
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nd.prdir[i] = r->rdir[i] - r->pert[i]; |
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if (DOT(nd.prdir, r->ron) < -FTINY) |
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normalize(nd.prdir); /* OK */ |
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else |
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if (rv[1] <= FTINY) |
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d = 1.0; |
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else |
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< |
d = sqrt( np->alpha2/4.0 * -log(rv[1]) ); |
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> |
d = sqrt( -log(rv[1]) * np->alpha2 ); |
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for (i = 0; i < 3; i++) |
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sr.rdir[i] = np->prdir[i] + d*(cosp*u[i] + sinp*v[i]); |
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if (DOT(sr.rdir, r->ron) < -FTINY) |
