| 1 |
#ifndef lint |
| 2 |
static const char RCSid[] = "$Id$"; |
| 3 |
#endif |
| 4 |
/* |
| 5 |
* normal.c - shading function for normal materials. |
| 6 |
* |
| 7 |
* 8/19/85 |
| 8 |
* 12/19/85 - added stuff for metals. |
| 9 |
* 6/26/87 - improved specular model. |
| 10 |
* 9/28/87 - added model for translucent materials. |
| 11 |
* Later changes described in delta comments. |
| 12 |
*/ |
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|
| 14 |
#include "copyright.h" |
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|
| 16 |
#include "ray.h" |
| 17 |
|
| 18 |
#include "otypes.h" |
| 19 |
|
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#include "random.h" |
| 21 |
|
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#ifndef MAXITER |
| 23 |
#define MAXITER 10 /* maximum # specular ray attempts */ |
| 24 |
#endif |
| 25 |
/* estimate of Fresnel function */ |
| 26 |
#define FRESNE(ci) (exp(-6.0*(ci)) - 0.00247875217) |
| 27 |
|
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static void gaussamp(); |
| 29 |
|
| 30 |
/* |
| 31 |
* This routine implements the isotropic Gaussian |
| 32 |
* model described by Ward in Siggraph `92 article. |
| 33 |
* We orient the surface towards the incoming ray, so a single |
| 34 |
* surface can be used to represent an infinitely thin object. |
| 35 |
* |
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* Arguments for MAT_PLASTIC and MAT_METAL are: |
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* red grn blu specular-frac. facet-slope |
| 38 |
* |
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* Arguments for MAT_TRANS are: |
| 40 |
* red grn blu rspec rough trans tspec |
| 41 |
*/ |
| 42 |
|
| 43 |
/* specularity flags */ |
| 44 |
#define SP_REFL 01 /* has reflected specular component */ |
| 45 |
#define SP_TRAN 02 /* has transmitted specular */ |
| 46 |
#define SP_PURE 04 /* purely specular (zero roughness) */ |
| 47 |
#define SP_FLAT 010 /* flat reflecting surface */ |
| 48 |
#define SP_RBLT 020 /* reflection below sample threshold */ |
| 49 |
#define SP_TBLT 040 /* transmission below threshold */ |
| 50 |
|
| 51 |
typedef struct { |
| 52 |
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 direction of reflected ray */ |
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FVECT prdir; /* vector in transmitted direction */ |
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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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FVECT pnorm; /* perturbed surface normal */ |
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double pdot; /* perturbed dot product */ |
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} NORMDAT; /* normal material data */ |
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|
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|
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static void |
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dirnorm(cval, np, ldir, omega) /* compute source contribution */ |
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COLOR cval; /* returned coefficient */ |
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register NORMDAT *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 ldiff; |
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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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|
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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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/* Fresnel estimate */ |
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ldiff = np->rdiff; |
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if (np->specfl & SP_PURE && (np->rspec > FTINY & ldiff > FTINY)) |
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ldiff *= 1. - FRESNE(fabs(ldot)); |
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|
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if (ldot > FTINY && ldiff > 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 * ldiff / 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_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 */ |
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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/(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(-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 * 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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} |
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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_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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/* roughness + source */ |
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dtmp = np->alpha2 + omega/PI; |
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/* gaussian */ |
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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 * 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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} |
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} |
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|
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|
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int |
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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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NORMDAT nd; |
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double fest; |
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double transtest, transdist; |
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double mirtest, mirdist; |
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int hastexture; |
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double d; |
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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 && m->otype != MAT_TRANS) |
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return(1); |
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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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/* check for back side */ |
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if (r->rod < 0.0) { |
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if (!backvis && m->otype != MAT_TRANS) { |
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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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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.alpha2 = m->oargs.farg[4]; |
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if ((nd.alpha2 *= nd.alpha2) <= FTINY) |
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nd.specfl |= SP_PURE; |
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if (r->ro != NULL && isflat(r->ro->otype)) |
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nd.specfl |= SP_FLAT; |
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/* get modifiers */ |
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raytexture(r, m->omod); |
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if (hastexture = DOT(r->pert,r->pert) > FTINY*FTINY) |
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nd.pdot = raynormal(nd.pnorm, r); /* perturb normal */ |
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else { |
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VCOPY(nd.pnorm, r->ron); |
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nd.pdot = r->rod; |
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} |
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if (nd.pdot < .001) |
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nd.pdot = .001; /* non-zero for dirnorm() */ |
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multcolor(nd.mcolor, r->pcol); /* modify material color */ |
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mirtest = transtest = 0; |
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mirdist = transdist = r->rot; |
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nd.rspec = m->oargs.farg[3]; |
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/* compute Fresnel approx. */ |
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if (nd.specfl & SP_PURE && nd.rspec > FTINY) { |
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fest = FRESNE(r->rod); |
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nd.rspec += fest*(1. - nd.rspec); |
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} else |
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fest = 0.; |
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/* compute transmission */ |
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if (m->otype == MAT_TRANS) { |
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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 (nd.tspec > FTINY) { |
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nd.specfl |= SP_TRAN; |
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/* check threshold */ |
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if (!(nd.specfl & SP_PURE) && |
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specthresh >= nd.tspec-FTINY) |
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nd.specfl |= SP_TBLT; |
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if (!hastexture || r->crtype & SHADOW) { |
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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] - 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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/* transmitted ray */ |
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if ((nd.specfl&(SP_TRAN|SP_PURE|SP_TBLT)) == (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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rayvalue(&lr); |
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scalecolor(lr.rcol, nd.tspec); |
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multcolor(lr.rcol, nd.mcolor); /* modified by color */ |
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addcolor(r->rcol, lr.rcol); |
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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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} else |
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transtest = 0; |
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|
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if (r->crtype & SHADOW) { /* the rest is shadow */ |
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r->rt = transdist; |
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return(1); |
| 263 |
} |
| 264 |
/* get specular reflection */ |
| 265 |
if (nd.rspec > FTINY) { |
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nd.specfl |= SP_REFL; |
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/* compute specular color */ |
| 268 |
if (m->otype != MAT_METAL) { |
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setcolor(nd.scolor, nd.rspec, nd.rspec, nd.rspec); |
| 270 |
} else if (fest > FTINY) { |
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d = nd.rspec*(1. - fest); |
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for (i = 0; i < 3; i++) |
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nd.scolor[i] = fest + nd.mcolor[i]*d; |
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} else { |
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copycolor(nd.scolor, nd.mcolor); |
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scalecolor(nd.scolor, nd.rspec); |
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} |
| 278 |
/* check threshold */ |
| 279 |
if (!(nd.specfl & SP_PURE) && specthresh >= nd.rspec-FTINY) |
| 280 |
nd.specfl |= SP_RBLT; |
| 281 |
/* compute reflected ray */ |
| 282 |
for (i = 0; i < 3; i++) |
| 283 |
nd.vrefl[i] = r->rdir[i] + 2.*nd.pdot*nd.pnorm[i]; |
| 284 |
/* penetration? */ |
| 285 |
if (hastexture && DOT(nd.vrefl, r->ron) <= FTINY) |
| 286 |
for (i = 0; i < 3; i++) /* safety measure */ |
| 287 |
nd.vrefl[i] = r->rdir[i] + 2.*r->rod*r->ron[i]; |
| 288 |
} |
| 289 |
/* reflected ray */ |
| 290 |
if ((nd.specfl&(SP_REFL|SP_PURE|SP_RBLT)) == (SP_REFL|SP_PURE)) { |
| 291 |
RAY lr; |
| 292 |
if (rayorigin(&lr, r, REFLECTED, nd.rspec) == 0) { |
| 293 |
VCOPY(lr.rdir, nd.vrefl); |
| 294 |
rayvalue(&lr); |
| 295 |
multcolor(lr.rcol, nd.scolor); |
| 296 |
addcolor(r->rcol, lr.rcol); |
| 297 |
if (!hastexture && nd.specfl & SP_FLAT) { |
| 298 |
mirtest = 2.*bright(lr.rcol); |
| 299 |
mirdist = r->rot + lr.rt; |
| 300 |
} |
| 301 |
} |
| 302 |
} |
| 303 |
/* diffuse reflection */ |
| 304 |
nd.rdiff = 1.0 - nd.trans - nd.rspec; |
| 305 |
|
| 306 |
if (nd.specfl & SP_PURE && nd.rdiff <= FTINY && nd.tdiff <= FTINY) |
| 307 |
return(1); /* 100% pure specular */ |
| 308 |
|
| 309 |
if (!(nd.specfl & SP_PURE)) |
| 310 |
gaussamp(r, &nd); /* checks *BLT flags */ |
| 311 |
|
| 312 |
if (nd.rdiff > FTINY) { /* ambient from this side */ |
| 313 |
ambient(ctmp, r, hastexture?nd.pnorm:r->ron); |
| 314 |
if (nd.specfl & SP_RBLT) |
| 315 |
scalecolor(ctmp, 1.0-nd.trans); |
| 316 |
else |
| 317 |
scalecolor(ctmp, nd.rdiff); |
| 318 |
multcolor(ctmp, nd.mcolor); /* modified by material color */ |
| 319 |
addcolor(r->rcol, ctmp); /* add to returned color */ |
| 320 |
} |
| 321 |
if (nd.tdiff > FTINY) { /* ambient from other side */ |
| 322 |
flipsurface(r); |
| 323 |
if (hastexture) { |
| 324 |
FVECT bnorm; |
| 325 |
bnorm[0] = -nd.pnorm[0]; |
| 326 |
bnorm[1] = -nd.pnorm[1]; |
| 327 |
bnorm[2] = -nd.pnorm[2]; |
| 328 |
ambient(ctmp, r, bnorm); |
| 329 |
} else |
| 330 |
ambient(ctmp, r, r->ron); |
| 331 |
if (nd.specfl & SP_TBLT) |
| 332 |
scalecolor(ctmp, nd.trans); |
| 333 |
else |
| 334 |
scalecolor(ctmp, nd.tdiff); |
| 335 |
multcolor(ctmp, nd.mcolor); /* modified by color */ |
| 336 |
addcolor(r->rcol, ctmp); |
| 337 |
flipsurface(r); |
| 338 |
} |
| 339 |
/* add direct component */ |
| 340 |
direct(r, dirnorm, &nd); |
| 341 |
/* check distance */ |
| 342 |
d = bright(r->rcol); |
| 343 |
if (transtest > d) |
| 344 |
r->rt = transdist; |
| 345 |
else if (mirtest > d) |
| 346 |
r->rt = mirdist; |
| 347 |
|
| 348 |
return(1); |
| 349 |
} |
| 350 |
|
| 351 |
|
| 352 |
static void |
| 353 |
gaussamp(r, np) /* sample gaussian specular */ |
| 354 |
RAY *r; |
| 355 |
register NORMDAT *np; |
| 356 |
{ |
| 357 |
RAY sr; |
| 358 |
FVECT u, v, h; |
| 359 |
double rv[2]; |
| 360 |
double d, sinp, cosp; |
| 361 |
int niter; |
| 362 |
register int i; |
| 363 |
/* quick test */ |
| 364 |
if ((np->specfl & (SP_REFL|SP_RBLT)) != SP_REFL && |
| 365 |
(np->specfl & (SP_TRAN|SP_TBLT)) != SP_TRAN) |
| 366 |
return; |
| 367 |
/* set up sample coordinates */ |
| 368 |
v[0] = v[1] = v[2] = 0.0; |
| 369 |
for (i = 0; i < 3; i++) |
| 370 |
if (np->pnorm[i] < 0.6 && np->pnorm[i] > -0.6) |
| 371 |
break; |
| 372 |
v[i] = 1.0; |
| 373 |
fcross(u, v, np->pnorm); |
| 374 |
normalize(u); |
| 375 |
fcross(v, np->pnorm, u); |
| 376 |
/* compute reflection */ |
| 377 |
if ((np->specfl & (SP_REFL|SP_RBLT)) == SP_REFL && |
| 378 |
rayorigin(&sr, r, SPECULAR, np->rspec) == 0) { |
| 379 |
dimlist[ndims++] = (int)np->mp; |
| 380 |
for (niter = 0; niter < MAXITER; niter++) { |
| 381 |
if (niter) |
| 382 |
d = frandom(); |
| 383 |
else |
| 384 |
d = urand(ilhash(dimlist,ndims)+samplendx); |
| 385 |
multisamp(rv, 2, d); |
| 386 |
d = 2.0*PI * rv[0]; |
| 387 |
cosp = tcos(d); |
| 388 |
sinp = tsin(d); |
| 389 |
rv[1] = 1.0 - specjitter*rv[1]; |
| 390 |
if (rv[1] <= FTINY) |
| 391 |
d = 1.0; |
| 392 |
else |
| 393 |
d = sqrt( np->alpha2 * -log(rv[1]) ); |
| 394 |
for (i = 0; i < 3; i++) |
| 395 |
h[i] = np->pnorm[i] + d*(cosp*u[i] + sinp*v[i]); |
| 396 |
d = -2.0 * DOT(h, r->rdir) / (1.0 + d*d); |
| 397 |
for (i = 0; i < 3; i++) |
| 398 |
sr.rdir[i] = r->rdir[i] + d*h[i]; |
| 399 |
if (DOT(sr.rdir, r->ron) > FTINY) { |
| 400 |
rayvalue(&sr); |
| 401 |
multcolor(sr.rcol, np->scolor); |
| 402 |
addcolor(r->rcol, sr.rcol); |
| 403 |
break; |
| 404 |
} |
| 405 |
} |
| 406 |
ndims--; |
| 407 |
} |
| 408 |
/* compute transmission */ |
| 409 |
if ((np->specfl & (SP_TRAN|SP_TBLT)) == SP_TRAN && |
| 410 |
rayorigin(&sr, r, SPECULAR, np->tspec) == 0) { |
| 411 |
dimlist[ndims++] = (int)np->mp; |
| 412 |
for (niter = 0; niter < MAXITER; niter++) { |
| 413 |
if (niter) |
| 414 |
d = frandom(); |
| 415 |
else |
| 416 |
d = urand(ilhash(dimlist,ndims)+1823+samplendx); |
| 417 |
multisamp(rv, 2, d); |
| 418 |
d = 2.0*PI * rv[0]; |
| 419 |
cosp = tcos(d); |
| 420 |
sinp = tsin(d); |
| 421 |
rv[1] = 1.0 - specjitter*rv[1]; |
| 422 |
if (rv[1] <= FTINY) |
| 423 |
d = 1.0; |
| 424 |
else |
| 425 |
d = sqrt( np->alpha2 * -log(rv[1]) ); |
| 426 |
for (i = 0; i < 3; i++) |
| 427 |
sr.rdir[i] = np->prdir[i] + d*(cosp*u[i] + sinp*v[i]); |
| 428 |
if (DOT(sr.rdir, r->ron) < -FTINY) { |
| 429 |
normalize(sr.rdir); /* OK, normalize */ |
| 430 |
rayvalue(&sr); |
| 431 |
scalecolor(sr.rcol, np->tspec); |
| 432 |
multcolor(sr.rcol, np->mcolor); /* modified */ |
| 433 |
addcolor(r->rcol, sr.rcol); |
| 434 |
break; |
| 435 |
} |
| 436 |
} |
| 437 |
ndims--; |
| 438 |
} |
| 439 |
} |
