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/* Copyright (c) 1991 Regents of the University of California */ |
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/* Copyright (c) 1992 Regents of the University of California */ |
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#ifndef lint |
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static char SCCSid[] = "$SunId$ LBL"; |
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* 12/19/85 - added stuff for metals. |
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* 6/26/87 - improved specular model. |
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* 9/28/87 - added model for translucent materials. |
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* Later changes described in delta comments. |
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*/ |
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#include "ray.h" |
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#include "otypes.h" |
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#include "random.h" |
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|
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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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#define BSPEC(m) (6.0) /* specularity parameter b */ |
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extern double exp(); |
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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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typedef struct { |
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OBJREC *mp; /* material 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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FVECT vrefl; /* vector in direction of reflected ray */ |
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FVECT prdir; /* vector in transmitted direction */ |
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double alpha2; /* roughness squared times 2 */ |
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double alpha2; /* roughness squared */ |
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double rdiff, rspec; /* reflected specular, diffuse */ |
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double trans; /* transmissivity */ |
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double tdiff, tspec; /* transmitted specular, diffuse */ |
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scalecolor(ctmp, dtmp); |
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addcolor(cval, ctmp); |
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} |
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if (ldot > FTINY && np->rspec > FTINY && np->alpha2 > FTINY) { |
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if (ldot > FTINY && (np->specfl&(SP_REFL|SP_PURE)) == SP_REFL) { |
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/* |
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* Compute specular reflection coefficient using |
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* gaussian distribution model. |
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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 = 2.0*np->alpha2 + omega/(2.0*PI); |
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/* gaussian */ |
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dtmp = exp((DOT(np->vrefl,ldir)-1.)/dtmp)/(2.*PI)/dtmp; |
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/* worth using? */ |
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scalecolor(ctmp, dtmp); |
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addcolor(cval, ctmp); |
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} |
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if (ldot < -FTINY && np->tspec > FTINY && np->alpha2 > FTINY) { |
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if (ldot < -FTINY && (np->specfl&(SP_TRAN|SP_PURE)) == SP_TRAN) { |
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/* |
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* Compute specular transmission. Specular transmission |
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* is always modified by material color. |
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} |
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m_normal(m, r) /* color a ray which hit something normal */ |
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m_normal(m, r) /* color a ray that hit something normal */ |
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register OBJREC *m; |
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register RAY *r; |
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{ |
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double dtmp; |
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COLOR ctmp; |
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register int i; |
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if (m->oargs.nfargs != (m->otype == MAT_TRANS ? 7 : 5)) |
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objerror(m, USER, "bad # arguments"); |
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/* easy shadow test */ |
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if (r->crtype & SHADOW && m->otype != MAT_TRANS) |
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return; |
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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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/* 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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m->oargs.farg[2]); |
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/* get roughness */ |
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nd.specfl = 0; |
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nd.alpha2 = m->oargs.farg[4]; |
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nd.alpha2 *= 2.0 * nd.alpha2; |
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if ((nd.alpha2 *= nd.alpha2) <= FTINY) |
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nd.specfl |= SP_PURE; |
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/* reorient if necessary */ |
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if (r->rod < 0.0) |
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flipsurface(r); |
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multcolor(nd.mcolor, r->pcol); /* modify material color */ |
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transtest = 0; |
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/* get specular component */ |
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nd.rspec = m->oargs.farg[3]; |
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if (nd.rspec > FTINY) { /* has specular component */ |
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if ((nd.rspec = m->oargs.farg[3]) > FTINY) { |
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nd.specfl |= SP_REFL; |
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/* compute specular color */ |
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if (m->otype == MAT_METAL) |
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copycolor(nd.scolor, nd.mcolor); |
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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 (nd.alpha2 <= FTINY && !(r->crtype & SHADOW)) { |
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if (!(r->crtype & SHADOW) && nd.specfl & SP_PURE) { |
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RAY lr; |
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if (rayorigin(&lr, r, REFLECTED, nd.rspec) == 0) { |
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VCOPY(lr.rdir, nd.vrefl); |
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nd.trans = m->oargs.farg[5]*(1.0 - nd.rspec); |
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nd.tspec = nd.trans * m->oargs.farg[6]; |
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nd.tdiff = nd.trans - nd.tspec; |
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if (r->crtype & SHADOW || DOT(r->pert,r->pert) <= FTINY*FTINY) { |
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VCOPY(nd.prdir, r->rdir); |
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transtest = 2; |
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} else { |
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for (i = 0; i < 3; i++) /* perturb direction */ |
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nd.prdir[i] = r->rdir[i] - .75*r->pert[i]; |
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normalize(nd.prdir); |
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if (nd.tspec > FTINY) { |
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nd.specfl |= SP_TRAN; |
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if (r->crtype & SHADOW || |
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DOT(r->pert,r->pert) <= FTINY*FTINY) { |
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VCOPY(nd.prdir, r->rdir); |
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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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} |
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} |
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} else |
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nd.tdiff = nd.tspec = nd.trans = 0.0; |
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/* transmitted ray */ |
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if (nd.tspec > FTINY && nd.alpha2 <= FTINY) { |
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if ((nd.specfl&(SP_TRAN|SP_PURE)) == (SP_TRAN|SP_PURE)) { |
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RAY lr; |
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if (rayorigin(&lr, r, TRANS, nd.tspec) == 0) { |
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VCOPY(lr.rdir, nd.prdir); |
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transdist = r->rot + lr.rt; |
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} |
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} |
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if (r->crtype & SHADOW) /* the rest is shadow */ |
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return; |
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/* diffuse reflection */ |
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nd.rdiff = 1.0 - nd.trans - nd.rspec; |
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if (nd.rdiff <= FTINY && nd.tdiff <= FTINY && nd.alpha2 <= FTINY) |
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return; /* purely specular */ |
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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 (nd.specfl & (SP_REFL|SP_TRAN) && !(nd.specfl & SP_PURE)) |
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gaussamp(r, &nd); |
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if (nd.rdiff > FTINY) { /* ambient from this side */ |
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ambient(ctmp, r); |
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if (nd.alpha2 <= FTINY) |
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scalecolor(ctmp, nd.rdiff); |
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else |
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scalecolor(ctmp, 1.0-nd.trans); |
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scalecolor(ctmp, nd.rdiff); |
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multcolor(ctmp, nd.mcolor); /* modified by material color */ |
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addcolor(r->rcol, ctmp); /* add to returned color */ |
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} |
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if (nd.tdiff > FTINY) { /* ambient from other side */ |
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flipsurface(r); |
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ambient(ctmp, r); |
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if (nd.alpha2 <= FTINY) |
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scalecolor(ctmp, nd.tdiff); |
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else |
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scalecolor(ctmp, nd.trans); |
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scalecolor(ctmp, nd.tdiff); |
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multcolor(ctmp, nd.mcolor); /* modified by color */ |
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addcolor(r->rcol, ctmp); |
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flipsurface(r); |
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/* check distance */ |
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if (transtest > bright(r->rcol)) |
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r->rt = transdist; |
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} |
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|
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static |
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gaussamp(r, np) /* sample gaussian specular */ |
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RAY *r; |
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register NORMDAT *np; |
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{ |
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RAY sr; |
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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 confuse; |
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register int i; |
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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->pnorm[i] < 0.6 && np->pnorm[i] > -0.6) |
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break; |
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v[i] = 1.0; |
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fcross(u, v, np->pnorm); |
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normalize(u); |
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fcross(v, np->pnorm, u); |
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/* compute reflection */ |
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if (np->specfl & SP_REFL && |
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rayorigin(&sr, r, SPECULAR, np->rspec) == 0) { |
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confuse = 0; |
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dimlist[ndims++] = (int)np->mp; |
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refagain: |
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dimlist[ndims] = confuse += 3601; |
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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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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) /* oops! */ |
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goto refagain; |
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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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} |
