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extern double specjitter; /* specular sampling jitter */ |
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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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/* specularity flags */ |
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#define SP_REFL 01 /* has reflected specular component */ |
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#define SP_TRAN 02 /* has transmitted specular */ |
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#define SP_PURE 010 /* purely specular (zero roughness) */ |
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#define SP_FLAT 020 /* flat reflecting surface */ |
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#define SP_RBLT 040 /* reflection below sample threshold */ |
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#define SP_TBLT 0100 /* transmission below threshold */ |
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#define SP_PURE 04 /* purely specular (zero roughness) */ |
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#define SP_FLAT 010 /* flat reflecting surface */ |
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#define SP_RBLT 020 /* reflection below sample threshold */ |
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#define SP_TBLT 040 /* transmission below threshold */ |
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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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|
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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 + 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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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.rspec <= specthresh+FTINY) |
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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 + .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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nd.vrefl[i] = r->rdir[i] + 2.0*nd.pdot*nd.pnorm[i]; |
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if (DOT(nd.vrefl, r->ron) <= FTINY) /* penetration? */ |
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for (i = 0; i < 3; i++) /* safety measure */ |
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nd.vrefl[i] = r->rdir[i] + 2.*r->rod*r->ron[i]; |
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if (!(r->crtype & SHADOW) && nd.specfl & SP_PURE) { |
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RAY lr; |
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if (nd.tspec > FTINY) { |
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nd.specfl |= SP_TRAN; |
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/* check threshold */ |
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if (nd.tspec <= specthresh+FTINY) |
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if (!(nd.specfl & SP_PURE) && specthresh > FTINY && |
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(specthresh >= 1.-FTINY || |
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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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.75*r->pert[i]; |
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normalize(nd.prdir); |
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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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VCOPY(nd.prdir, r->rdir); |
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} |
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} |
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} else |
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transtest *= bright(lr.rcol); |
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transdist = r->rot + lr.rt; |
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} |
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} |
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} else |
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transtest = 0; |
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if (r->crtype & SHADOW) /* the rest is shadow */ |
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return; |
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if (nd.specfl & SP_PURE && nd.rdiff <= FTINY && nd.tdiff <= FTINY) |
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return; /* 100% pure specular */ |
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if (r->ro->otype == OBJ_FACE || r->ro->otype == OBJ_RING) |
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if (r->ro != NULL && (r->ro->otype == OBJ_FACE || |
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r->ro->otype == OBJ_RING)) |
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nd.specfl |= SP_FLAT; |
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|
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if (nd.specfl & (SP_REFL|SP_TRAN) && !(nd.specfl & SP_PURE)) |
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FVECT u, v, h; |
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double rv[2]; |
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double d, sinp, cosp; |
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int ntries; |
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register int i; |
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/* quick test */ |
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if ((np->specfl & (SP_REFL|SP_RBLT)) != SP_REFL && |
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(np->specfl & (SP_TRAN|SP_TBLT)) != SP_TRAN) |
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return; |
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/* set up sample coordinates */ |
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v[0] = v[1] = v[2] = 0.0; |
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for (i = 0; i < 3; i++) |
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if ((np->specfl & (SP_REFL|SP_RBLT)) == SP_REFL && |
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rayorigin(&sr, r, SPECULAR, np->rspec) == 0) { |
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dimlist[ndims++] = (int)np->mp; |
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for (ntries = 0; ntries < 10; ntries++) { |
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dimlist[ndims] = ntries * 8912; |
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d = urand(ilhash(dimlist,ndims+1)+samplendx); |
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multisamp(rv, 2, d); |
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d = 2.0*PI * rv[0]; |
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cosp = cos(d); |
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sinp = sin(d); |
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rv[1] = 1.0 - specjitter*rv[1]; |
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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 * -log(rv[1]) ); |
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for (i = 0; i < 3; i++) |
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h[i] = np->pnorm[i] + d*(cosp*u[i] + sinp*v[i]); |
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d = -2.0 * DOT(h, r->rdir) / (1.0 + d*d); |
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for (i = 0; i < 3; i++) |
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sr.rdir[i] = r->rdir[i] + d*h[i]; |
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if (DOT(sr.rdir, r->ron) > FTINY) { |
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rayvalue(&sr); |
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multcolor(sr.rcol, np->scolor); |
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addcolor(r->rcol, sr.rcol); |
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break; |
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} |
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} |
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> |
d = urand(ilhash(dimlist,ndims)+samplendx); |
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> |
multisamp(rv, 2, d); |
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> |
d = 2.0*PI * rv[0]; |
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cosp = cos(d); |
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sinp = sin(d); |
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rv[1] = 1.0 - specjitter*rv[1]; |
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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 * -log(rv[1]) ); |
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> |
for (i = 0; i < 3; i++) |
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h[i] = np->pnorm[i] + d*(cosp*u[i] + sinp*v[i]); |
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d = -2.0 * DOT(h, r->rdir) / (1.0 + d*d); |
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for (i = 0; i < 3; i++) |
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sr.rdir[i] = r->rdir[i] + d*h[i]; |
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> |
if (DOT(sr.rdir, r->ron) <= FTINY) |
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> |
VCOPY(sr.rdir, np->vrefl); /* jitter no good */ |
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> |
rayvalue(&sr); |
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> |
multcolor(sr.rcol, np->scolor); |
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> |
addcolor(r->rcol, sr.rcol); |
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ndims--; |
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} |
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/* compute transmission */ |
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+ |
if ((np->specfl & (SP_TRAN|SP_TBLT)) == SP_TRAN && |
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+ |
rayorigin(&sr, r, SPECULAR, np->tspec) == 0) { |
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+ |
dimlist[ndims++] = (int)np->mp; |
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+ |
d = urand(ilhash(dimlist,ndims)+1823+samplendx); |
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+ |
multisamp(rv, 2, d); |
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+ |
d = 2.0*PI * rv[0]; |
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+ |
cosp = cos(d); |
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+ |
sinp = sin(d); |
| 367 |
+ |
rv[1] = 1.0 - specjitter*rv[1]; |
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+ |
if (rv[1] <= FTINY) |
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+ |
d = 1.0; |
| 370 |
+ |
else |
| 371 |
+ |
d = sqrt( -log(rv[1]) * np->alpha2 ); |
| 372 |
+ |
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) |
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normalize(sr.rdir); /* OK, normalize */ |
| 376 |
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else |
| 377 |
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VCOPY(sr.rdir, np->prdir); /* else no jitter */ |
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+ |
rayvalue(&sr); |
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+ |
scalecolor(sr.rcol, np->tspec); |
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+ |
multcolor(sr.rcol, np->mcolor); /* modified by color */ |
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+ |
addcolor(r->rcol, sr.rcol); |
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+ |
ndims--; |
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+ |
} |
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} |
