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#ifndef lint |
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static const char RCSid[] = "$Id$"; |
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#endif |
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/* |
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* Shading functions for anisotropic materials. |
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*/ |
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|
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#include "copyright.h" |
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|
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#include "ray.h" |
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|
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#include "otypes.h" |
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|
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#include "func.h" |
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|
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#include "random.h" |
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|
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#ifndef MAXITER |
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#define MAXITER 10 /* maximum # specular ray attempts */ |
| 20 |
#endif |
| 21 |
|
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/* |
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* This routine implements the anisotropic 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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* Arguments for MAT_PLASTIC2 and MAT_METAL2 are: |
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* 4+ ux uy uz funcfile [transform...] |
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* 0 |
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* 6 red grn blu specular-frac. u-facet-slope v-facet-slope |
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* |
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* Real arguments for MAT_TRANS2 are: |
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* 8 red grn blu rspec u-rough v-rough trans tspec |
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*/ |
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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_FLAT 04 /* reflecting surface is flat */ |
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#define SP_RBLT 010 /* reflection below sample threshold */ |
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#define SP_TBLT 020 /* transmission below threshold */ |
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#define SP_BADU 040 /* bad u direction calculation */ |
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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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FVECT vrefl; /* vector in reflected direction */ |
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FVECT prdir; /* vector in transmitted direction */ |
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FVECT u, v; /* u and v vectors orienting anisotropy */ |
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double u_alpha; /* u roughness */ |
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double v_alpha; /* v roughness */ |
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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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FVECT pnorm; /* perturbed surface normal */ |
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double pdot; /* perturbed dot product */ |
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} ANISODAT; /* anisotropic material data */ |
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|
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static void getacoords(); |
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static void agaussamp(); |
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|
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|
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static void |
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diraniso(cval, np, ldir, omega) /* compute source contribution */ |
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COLOR cval; /* returned coefficient */ |
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register ANISODAT *np; /* material data */ |
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FVECT ldir; /* light source direction */ |
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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, dtmp1, dtmp2; |
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FVECT h; |
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double au2, av2; |
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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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|
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ldot = DOT(np->pnorm, ldir); |
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|
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if (ldot < 0.0 ? np->trans <= FTINY : np->trans >= 1.0-FTINY) |
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return; /* wrong side */ |
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|
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if (ldot > FTINY && np->rdiff > FTINY) { |
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/* |
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* Compute and add diffuse reflected component to returned |
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* color. The diffuse reflected component will always be |
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* modified by the color of the material. |
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*/ |
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copycolor(ctmp, np->mcolor); |
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dtmp = ldot * omega * np->rdiff / PI; |
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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->specfl&(SP_REFL|SP_BADU)) == SP_REFL) { |
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/* |
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* Compute specular reflection coefficient using |
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* anisotropic gaussian distribution model. |
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*/ |
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/* add source width if flat */ |
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if (np->specfl & SP_FLAT) |
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au2 = av2 = omega/(4.0*PI); |
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else |
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au2 = av2 = 0.0; |
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au2 += np->u_alpha*np->u_alpha; |
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av2 += np->v_alpha*np->v_alpha; |
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/* half vector */ |
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h[0] = ldir[0] - np->rp->rdir[0]; |
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h[1] = ldir[1] - np->rp->rdir[1]; |
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h[2] = ldir[2] - np->rp->rdir[2]; |
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/* ellipse */ |
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dtmp1 = DOT(np->u, h); |
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dtmp1 *= dtmp1 / au2; |
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dtmp2 = DOT(np->v, h); |
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dtmp2 *= dtmp2 / av2; |
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/* gaussian */ |
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dtmp = DOT(np->pnorm, h); |
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dtmp = (dtmp1 + dtmp2) / (dtmp*dtmp); |
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dtmp = exp(-dtmp) * (0.25/PI) |
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* sqrt(ldot/(np->pdot*au2*av2)); |
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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; |
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scalecolor(ctmp, dtmp); |
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addcolor(cval, ctmp); |
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} |
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} |
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if (ldot < -FTINY && np->tdiff > FTINY) { |
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/* |
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* Compute diffuse transmission. |
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*/ |
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copycolor(ctmp, np->mcolor); |
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dtmp = -ldot * omega * np->tdiff / PI; |
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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->specfl&(SP_TRAN|SP_BADU)) == 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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/* roughness + source */ |
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au2 = av2 = omega / PI; |
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au2 += np->u_alpha*np->u_alpha; |
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av2 += np->v_alpha*np->v_alpha; |
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/* "half vector" */ |
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h[0] = ldir[0] - np->prdir[0]; |
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h[1] = ldir[1] - np->prdir[1]; |
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h[2] = ldir[2] - np->prdir[2]; |
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dtmp = DOT(h,h); |
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if (dtmp > FTINY*FTINY) { |
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dtmp1 = DOT(h,np->pnorm); |
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dtmp = 1.0 - dtmp1*dtmp1/dtmp; |
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if (dtmp > FTINY*FTINY) { |
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dtmp1 = DOT(h,np->u); |
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dtmp1 *= dtmp1 / au2; |
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dtmp2 = DOT(h,np->v); |
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dtmp2 *= dtmp2 / av2; |
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dtmp = (dtmp1 + dtmp2) / dtmp; |
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} |
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} else |
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dtmp = 0.0; |
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/* gaussian */ |
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dtmp = exp(-dtmp) * (1.0/PI) |
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* sqrt(-ldot/(np->pdot*au2*av2)); |
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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; |
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scalecolor(ctmp, dtmp); |
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addcolor(cval, ctmp); |
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} |
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} |
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} |
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|
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|
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int |
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m_aniso(m, r) /* shade ray that hit something anisotropic */ |
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register OBJREC *m; |
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register RAY *r; |
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{ |
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ANISODAT nd; |
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COLOR ctmp; |
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register int i; |
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/* easy shadow test */ |
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if (r->crtype & SHADOW) |
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return(1); |
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|
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if (m->oargs.nfargs != (m->otype == MAT_TRANS2 ? 8 : 6)) |
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objerror(m, USER, "bad number of real 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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m->oargs.farg[2]); |
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/* get roughness */ |
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nd.specfl = 0; |
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nd.u_alpha = m->oargs.farg[4]; |
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nd.v_alpha = m->oargs.farg[5]; |
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if (nd.u_alpha < FTINY || nd.v_alpha <= FTINY) |
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objerror(m, USER, "roughness too small"); |
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/* check for back side */ |
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if (r->rod < 0.0) { |
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if (!backvis && m->otype != MAT_TRANS2) { |
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raytrans(r); |
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return(1); |
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} |
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flipsurface(r); /* reorient if backvis */ |
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} |
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/* get modifiers */ |
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raytexture(r, m->omod); |
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nd.pdot = raynormal(nd.pnorm, r); /* perturb normal */ |
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if (nd.pdot < .001) |
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nd.pdot = .001; /* non-zero for diraniso() */ |
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multcolor(nd.mcolor, r->pcol); /* modify material color */ |
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/* get 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_METAL2) |
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copycolor(nd.scolor, nd.mcolor); |
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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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/* check threshold */ |
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if (specthresh >= nd.rspec-FTINY) |
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nd.specfl |= SP_RBLT; |
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/* compute refl. direction */ |
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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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} |
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/* compute transmission */ |
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if (m->otype == MAT_TRANS2) { |
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nd.trans = m->oargs.farg[6]*(1.0 - nd.rspec); |
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nd.tspec = nd.trans * m->oargs.farg[7]; |
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nd.tdiff = nd.trans - nd.tspec; |
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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 (specthresh >= nd.tspec-FTINY) |
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nd.specfl |= SP_TBLT; |
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if (DOT(r->pert,r->pert) <= FTINY*FTINY) { |
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VCOPY(nd.prdir, r->rdir); |
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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] - 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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nd.tdiff = nd.tspec = nd.trans = 0.0; |
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|
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/* diffuse reflection */ |
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nd.rdiff = 1.0 - nd.trans - nd.rspec; |
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|
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if (r->ro != NULL && isflat(r->ro->otype)) |
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nd.specfl |= SP_FLAT; |
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|
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getacoords(r, &nd); /* set up coordinates */ |
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|
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if (nd.specfl & (SP_REFL|SP_TRAN) && !(nd.specfl & SP_BADU)) |
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agaussamp(r, &nd); |
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|
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if (nd.rdiff > FTINY) { /* ambient from this side */ |
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ambient(ctmp, r, nd.pnorm); |
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if (nd.specfl & SP_RBLT) |
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scalecolor(ctmp, 1.0-nd.trans); |
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else |
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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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} |
| 284 |
if (nd.tdiff > FTINY) { /* ambient from other side */ |
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FVECT bnorm; |
| 286 |
|
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flipsurface(r); |
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bnorm[0] = -nd.pnorm[0]; |
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bnorm[1] = -nd.pnorm[1]; |
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bnorm[2] = -nd.pnorm[2]; |
| 291 |
ambient(ctmp, r, bnorm); |
| 292 |
if (nd.specfl & SP_TBLT) |
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scalecolor(ctmp, nd.trans); |
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else |
| 295 |
scalecolor(ctmp, nd.tdiff); |
| 296 |
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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} |
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/* add direct component */ |
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direct(r, diraniso, &nd); |
| 302 |
|
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return(1); |
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} |
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|
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|
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static void |
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getacoords(r, np) /* set up coordinate system */ |
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RAY *r; |
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register ANISODAT *np; |
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{ |
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register MFUNC *mf; |
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register int i; |
| 314 |
|
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mf = getfunc(np->mp, 3, 0x7, 1); |
| 316 |
setfunc(np->mp, r); |
| 317 |
errno = 0; |
| 318 |
for (i = 0; i < 3; i++) |
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np->u[i] = evalue(mf->ep[i]); |
| 320 |
if (errno) { |
| 321 |
objerror(np->mp, WARNING, "compute error"); |
| 322 |
np->specfl |= SP_BADU; |
| 323 |
return; |
| 324 |
} |
| 325 |
if (mf->f != &unitxf) |
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multv3(np->u, np->u, mf->f->xfm); |
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fcross(np->v, np->pnorm, np->u); |
| 328 |
if (normalize(np->v) == 0.0) { |
| 329 |
objerror(np->mp, WARNING, "illegal orientation vector"); |
| 330 |
np->specfl |= SP_BADU; |
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return; |
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} |
| 333 |
fcross(np->u, np->v, np->pnorm); |
| 334 |
} |
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|
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|
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static void |
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agaussamp(r, np) /* sample anisotropic gaussian specular */ |
| 339 |
RAY *r; |
| 340 |
register ANISODAT *np; |
| 341 |
{ |
| 342 |
RAY sr; |
| 343 |
FVECT h; |
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double rv[2]; |
| 345 |
double d, sinp, cosp; |
| 346 |
int niter; |
| 347 |
register int i; |
| 348 |
/* compute reflection */ |
| 349 |
if ((np->specfl & (SP_REFL|SP_RBLT)) == SP_REFL && |
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rayorigin(&sr, r, SPECULAR, np->rspec) == 0) { |
| 351 |
dimlist[ndims++] = (int)np->mp; |
| 352 |
for (niter = 0; niter < MAXITER; niter++) { |
| 353 |
if (niter) |
| 354 |
d = frandom(); |
| 355 |
else |
| 356 |
d = urand(ilhash(dimlist,ndims)+samplendx); |
| 357 |
multisamp(rv, 2, d); |
| 358 |
d = 2.0*PI * rv[0]; |
| 359 |
cosp = tcos(d) * np->u_alpha; |
| 360 |
sinp = tsin(d) * np->v_alpha; |
| 361 |
d = sqrt(cosp*cosp + sinp*sinp); |
| 362 |
cosp /= d; |
| 363 |
sinp /= d; |
| 364 |
rv[1] = 1.0 - specjitter*rv[1]; |
| 365 |
if (rv[1] <= FTINY) |
| 366 |
d = 1.0; |
| 367 |
else |
| 368 |
d = sqrt(-log(rv[1]) / |
| 369 |
(cosp*cosp/(np->u_alpha*np->u_alpha) + |
| 370 |
sinp*sinp/(np->v_alpha*np->v_alpha))); |
| 371 |
for (i = 0; i < 3; i++) |
| 372 |
h[i] = np->pnorm[i] + |
| 373 |
d*(cosp*np->u[i] + sinp*np->v[i]); |
| 374 |
d = -2.0 * DOT(h, r->rdir) / (1.0 + d*d); |
| 375 |
for (i = 0; i < 3; i++) |
| 376 |
sr.rdir[i] = r->rdir[i] + d*h[i]; |
| 377 |
if (DOT(sr.rdir, r->ron) > FTINY) { |
| 378 |
rayvalue(&sr); |
| 379 |
multcolor(sr.rcol, np->scolor); |
| 380 |
addcolor(r->rcol, sr.rcol); |
| 381 |
break; |
| 382 |
} |
| 383 |
} |
| 384 |
ndims--; |
| 385 |
} |
| 386 |
/* compute transmission */ |
| 387 |
if ((np->specfl & (SP_TRAN|SP_TBLT)) == SP_TRAN && |
| 388 |
rayorigin(&sr, r, SPECULAR, np->tspec) == 0) { |
| 389 |
dimlist[ndims++] = (int)np->mp; |
| 390 |
for (niter = 0; niter < MAXITER; niter++) { |
| 391 |
if (niter) |
| 392 |
d = frandom(); |
| 393 |
else |
| 394 |
d = urand(ilhash(dimlist,ndims)+1823+samplendx); |
| 395 |
multisamp(rv, 2, d); |
| 396 |
d = 2.0*PI * rv[0]; |
| 397 |
cosp = tcos(d) * np->u_alpha; |
| 398 |
sinp = tsin(d) * np->v_alpha; |
| 399 |
d = sqrt(cosp*cosp + sinp*sinp); |
| 400 |
cosp /= d; |
| 401 |
sinp /= d; |
| 402 |
rv[1] = 1.0 - specjitter*rv[1]; |
| 403 |
if (rv[1] <= FTINY) |
| 404 |
d = 1.0; |
| 405 |
else |
| 406 |
d = sqrt(-log(rv[1]) / |
| 407 |
(cosp*cosp/(np->u_alpha*np->u_alpha) + |
| 408 |
sinp*sinp/(np->v_alpha*np->v_alpha))); |
| 409 |
for (i = 0; i < 3; i++) |
| 410 |
sr.rdir[i] = np->prdir[i] + |
| 411 |
d*(cosp*np->u[i] + sinp*np->v[i]); |
| 412 |
if (DOT(sr.rdir, r->ron) < -FTINY) { |
| 413 |
normalize(sr.rdir); /* OK, normalize */ |
| 414 |
rayvalue(&sr); |
| 415 |
scalecolor(sr.rcol, np->tspec); |
| 416 |
multcolor(sr.rcol, np->mcolor); /* modify */ |
| 417 |
addcolor(r->rcol, sr.rcol); |
| 418 |
break; |
| 419 |
} |
| 420 |
} |
| 421 |
ndims--; |
| 422 |
} |
| 423 |
} |
