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#ifndef lint |
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static const char RCSid[] = "$Id: aniso.c,v 2.65 2024/12/05 19:23:43 greg Exp $"; |
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#endif |
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/* |
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* Shading functions for anisotropic materials. |
| 6 |
*/ |
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|
| 8 |
#include "copyright.h" |
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|
| 10 |
#include "ray.h" |
| 11 |
#include "ambient.h" |
| 12 |
#include "otypes.h" |
| 13 |
#include "rtotypes.h" |
| 14 |
#include "source.h" |
| 15 |
#include "func.h" |
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#include "random.h" |
| 17 |
#include "pmapmat.h" |
| 18 |
|
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#ifndef MAXITER |
| 20 |
#define MAXITER 10 /* maximum # specular ray attempts */ |
| 21 |
#endif |
| 22 |
|
| 23 |
/* |
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* This routine implements the anisotropic Gaussian |
| 25 |
* model described by Ward in Siggraph `92 article, updated with |
| 26 |
* normalization and sampling adjustments due to Geisler-Moroder and Duer. |
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* We orient the surface towards the incoming ray, so a single |
| 28 |
* surface can be used to represent an infinitely thin object. |
| 29 |
* |
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* Arguments for MAT_PLASTIC2 and MAT_METAL2 are: |
| 31 |
* 4+ ux uy uz funcfile [transform...] |
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* 0 |
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* 6 red grn blu specular-frac. u-rough v-rough |
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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 |
| 37 |
*/ |
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|
| 39 |
/* specularity flags */ |
| 40 |
#define SP_REFL 01 /* has reflected specular component */ |
| 41 |
#define SP_TRAN 02 /* has transmitted specular */ |
| 42 |
#define SP_FLAT 04 /* reflecting surface is flat */ |
| 43 |
#define SP_RBLT 010 /* reflection below sample threshold */ |
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#define SP_TBLT 020 /* transmission below threshold */ |
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|
| 46 |
typedef struct { |
| 47 |
OBJREC *mp; /* material pointer */ |
| 48 |
RAY *rp; /* ray pointer */ |
| 49 |
short specfl; /* specularity flags, defined above */ |
| 50 |
SCOLOR mcolor; /* color of this material */ |
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SCOLOR scolor; /* color of specular component */ |
| 52 |
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 */ |
| 61 |
} ANISODAT; /* anisotropic material data */ |
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|
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static void getacoords(ANISODAT *np); |
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static void agaussamp(ANISODAT *np); |
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|
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|
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static void |
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diraniso( /* compute source contribution */ |
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SCOLOR scval, /* returned coefficient */ |
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void *nnp, /* 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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{ |
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ANISODAT *np = nnp; |
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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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SCOLOR sctmp; |
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|
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scolorblack(scval); |
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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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|
| 89 |
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 |
| 93 |
* modified by the color of the material. |
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*/ |
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copyscolor(sctmp, np->mcolor); |
| 96 |
dtmp = ldot * omega * np->rdiff * (1.0/PI); |
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scalescolor(sctmp, dtmp); |
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saddscolor(scval, sctmp); |
| 99 |
} |
| 100 |
|
| 101 |
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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copyscolor(sctmp, np->mcolor); |
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dtmp = -ldot * omega * np->tdiff * (1.0/PI); |
| 107 |
scalescolor(sctmp, dtmp); |
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saddscolor(scval, sctmp); |
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} |
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|
| 111 |
if (ambRayInPmap(np->rp)) |
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return; /* specular accounted for in photon map */ |
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|
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if (ldot > FTINY && np->specfl&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 * (0.25/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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VSUB(h, ldir, np->rp->rdir); |
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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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/* new W-G-M-D model */ |
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dtmp = DOT(np->pnorm, h); |
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dtmp *= dtmp; |
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dtmp1 = (dtmp1 + dtmp2) / dtmp; |
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dtmp = exp(-dtmp1) * DOT(h,h) / |
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(PI * dtmp*dtmp * sqrt(au2*av2)); |
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/* worth using? */ |
| 140 |
if (dtmp > FTINY) { |
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copyscolor(sctmp, np->scolor); |
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dtmp *= ldot * omega; |
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scalescolor(sctmp, dtmp); |
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saddscolor(scval, sctmp); |
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} |
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} |
| 147 |
|
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if (ldot < -FTINY && np->specfl&SP_TRAN) { |
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/* |
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* Compute specular transmission. Specular transmission |
| 151 |
* is always modified by material color. |
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*/ |
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/* roughness + source */ |
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au2 = av2 = omega * (1.0/PI); |
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au2 += np->u_alpha*np->u_alpha; |
| 156 |
av2 += np->v_alpha*np->v_alpha; |
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/* "half vector" */ |
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VSUB(h, ldir, np->prdir); |
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dtmp = DOT(h,h); |
| 160 |
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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} |
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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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dtmp = exp(-dtmp); |
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} else |
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dtmp = 1.0; |
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/* Gaussian */ |
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dtmp *= (1.0/PI) * sqrt(-ldot/(np->pdot*au2*av2)); |
| 175 |
/* worth using? */ |
| 176 |
if (dtmp > FTINY) { |
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copyscolor(sctmp, np->mcolor); |
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dtmp *= np->tspec * omega; |
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scalescolor(sctmp, dtmp); |
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saddscolor(scval, sctmp); |
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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( /* shade ray that hit something anisotropic */ |
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OBJREC *m, |
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RAY *r |
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) |
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{ |
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ANISODAT nd; |
| 193 |
SCOLOR sctmp; |
| 194 |
int i; |
| 195 |
/* easy shadow test */ |
| 196 |
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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/* check for back side */ |
| 202 |
if (r->rod < 0.0) { |
| 203 |
if (!backvis) { |
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raytrans(r); |
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return(1); |
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} |
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raytexture(r, m->omod); |
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flipsurface(r); /* reorient if backvis */ |
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} else |
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raytexture(r, m->omod); |
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/* get material color */ |
| 212 |
nd.mp = m; |
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nd.rp = r; |
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setscolor(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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|
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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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smultscolor(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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copyscolor(nd.scolor, nd.mcolor); |
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else |
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setscolor(nd.scolor, 1.0, 1.0, 1.0); |
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scalescolor(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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} |
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/* compute transmission */ |
| 242 |
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; |
| 246 |
if (nd.tspec > FTINY) { |
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nd.specfl |= SP_TRAN; |
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/* check threshold */ |
| 249 |
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]; |
| 256 |
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; |
| 264 |
|
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/* diffuse reflection */ |
| 266 |
nd.rdiff = 1.0 - nd.trans - nd.rspec; |
| 267 |
|
| 268 |
if (r->ro != NULL && isflat(r->ro->otype)) |
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nd.specfl |= SP_FLAT; |
| 270 |
|
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getacoords(&nd); /* set up coordinates */ |
| 272 |
|
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if (nd.specfl & (SP_REFL|SP_TRAN)) |
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agaussamp(&nd); |
| 275 |
|
| 276 |
if (nd.rdiff > FTINY) { /* ambient from this side */ |
| 277 |
copyscolor(sctmp, nd.mcolor); /* modified by material color */ |
| 278 |
scalescolor(sctmp, nd.rdiff); |
| 279 |
if (nd.specfl & SP_RBLT) /* add in specular as well? */ |
| 280 |
saddscolor(sctmp, nd.scolor); |
| 281 |
multambient(sctmp, r, nd.pnorm); |
| 282 |
saddscolor(r->rcol, sctmp); /* add to returned color */ |
| 283 |
} |
| 284 |
|
| 285 |
if (nd.tdiff > FTINY) { /* ambient from other side */ |
| 286 |
FVECT bnorm; |
| 287 |
bnorm[0] = -nd.pnorm[0]; |
| 288 |
bnorm[1] = -nd.pnorm[1]; |
| 289 |
bnorm[2] = -nd.pnorm[2]; |
| 290 |
copyscolor(sctmp, nd.mcolor); /* modified by color */ |
| 291 |
if (nd.specfl & SP_TBLT) { |
| 292 |
scalescolor(sctmp, nd.trans); |
| 293 |
} else { |
| 294 |
scalescolor(sctmp, nd.tdiff); |
| 295 |
} |
| 296 |
multambient(sctmp, r, bnorm); |
| 297 |
saddscolor(r->rcol, sctmp); |
| 298 |
} |
| 299 |
/* add direct component */ |
| 300 |
direct(r, diraniso, &nd); |
| 301 |
|
| 302 |
return(1); |
| 303 |
} |
| 304 |
|
| 305 |
static void |
| 306 |
getacoords( /* set up coordinate system */ |
| 307 |
ANISODAT *np |
| 308 |
) |
| 309 |
{ |
| 310 |
MFUNC *mf; |
| 311 |
int i; |
| 312 |
|
| 313 |
mf = getfunc(np->mp, 3, 0x7, 1); |
| 314 |
setfunc(np->mp, np->rp); |
| 315 |
errno = 0; |
| 316 |
for (i = 0; i < 3; i++) |
| 317 |
np->u[i] = evalue(mf->ep[i]); |
| 318 |
if ((errno == EDOM) | (errno == ERANGE)) |
| 319 |
np->u[0] = np->u[1] = np->u[2] = 0.0; |
| 320 |
else if (mf->fxp != &unitxf) |
| 321 |
multv3(np->u, np->u, mf->fxp->xfm); |
| 322 |
fcross(np->v, np->pnorm, np->u); |
| 323 |
if (normalize(np->v) == 0.0) { |
| 324 |
if (fabs(np->u_alpha - np->v_alpha) > 0.001) |
| 325 |
objerror(np->mp, WARNING, "illegal orientation vector"); |
| 326 |
getperpendicular(np->u, np->pnorm, 1); /* punting */ |
| 327 |
fcross(np->v, np->pnorm, np->u); |
| 328 |
np->u_alpha = np->v_alpha = sqrt( 0.5 * |
| 329 |
(np->u_alpha*np->u_alpha + np->v_alpha*np->v_alpha) ); |
| 330 |
} else |
| 331 |
fcross(np->u, np->v, np->pnorm); |
| 332 |
} |
| 333 |
|
| 334 |
|
| 335 |
static void |
| 336 |
agaussamp( /* sample anisotropic Gaussian specular */ |
| 337 |
ANISODAT *np |
| 338 |
) |
| 339 |
{ |
| 340 |
RAY sr; |
| 341 |
FVECT h; |
| 342 |
double rv[2]; |
| 343 |
double d, sinp, cosp; |
| 344 |
int maxiter, ntrials, nstarget, nstaken; |
| 345 |
int i; |
| 346 |
/* compute reflection */ |
| 347 |
if ((np->specfl & (SP_REFL|SP_RBLT)) == SP_REFL && |
| 348 |
rayorigin(&sr, RSPECULAR, np->rp, np->scolor) == 0) { |
| 349 |
SCOLOR scol; |
| 350 |
nstarget = 1; |
| 351 |
if (specjitter > 1.5) { /* multiple samples? */ |
| 352 |
nstarget = specjitter*np->rp->rweight + .5; |
| 353 |
if (sr.rweight <= minweight*nstarget) |
| 354 |
nstarget = sr.rweight/minweight; |
| 355 |
if (nstarget > 1) { |
| 356 |
d = 1./nstarget; |
| 357 |
scalescolor(sr.rcoef, d); |
| 358 |
sr.rweight *= d; |
| 359 |
} else |
| 360 |
nstarget = 1; |
| 361 |
} |
| 362 |
scolorblack(scol); |
| 363 |
dimlist[ndims++] = (int)(size_t)np->mp; |
| 364 |
maxiter = MAXITER*nstarget; |
| 365 |
for (nstaken = ntrials = 0; (nstaken < nstarget) & |
| 366 |
(ntrials < maxiter); ntrials++) { |
| 367 |
if (ntrials) |
| 368 |
d = frandom(); |
| 369 |
else |
| 370 |
d = urand(ilhash(dimlist,ndims)+samplendx); |
| 371 |
multisamp(rv, 2, d); |
| 372 |
d = 2.0*PI * rv[0]; |
| 373 |
cosp = tcos(d) * np->u_alpha; |
| 374 |
sinp = tsin(d) * np->v_alpha; |
| 375 |
d = 1./sqrt(cosp*cosp + sinp*sinp); |
| 376 |
cosp *= d; |
| 377 |
sinp *= d; |
| 378 |
if ((0. <= specjitter) & (specjitter < 1.)) |
| 379 |
rv[1] = 1.0 - specjitter*rv[1]; |
| 380 |
d = (rv[1] <= FTINY) ? 1.0 : sqrt( -log(rv[1]) / |
| 381 |
(cosp*cosp/(np->u_alpha*np->u_alpha) + |
| 382 |
sinp*sinp/(np->v_alpha*np->v_alpha)) ); |
| 383 |
for (i = 0; i < 3; i++) |
| 384 |
h[i] = np->pnorm[i] + |
| 385 |
d*(cosp*np->u[i] + sinp*np->v[i]); |
| 386 |
d = -2.0 * DOT(h, np->rp->rdir) / (1.0 + d*d); |
| 387 |
VSUM(sr.rdir, np->rp->rdir, h, d); |
| 388 |
/* sample rejection test */ |
| 389 |
if ((d = DOT(sr.rdir, np->rp->ron)) <= FTINY) |
| 390 |
continue; |
| 391 |
checknorm(sr.rdir); |
| 392 |
if (nstarget > 1) { /* W-G-M-D adjustment */ |
| 393 |
if (nstaken) rayclear(&sr); |
| 394 |
rayvalue(&sr); |
| 395 |
d = 2./(1. + np->rp->rod/d); |
| 396 |
scalescolor(sr.rcol, d); |
| 397 |
saddscolor(scol, sr.rcol); |
| 398 |
} else { |
| 399 |
rayvalue(&sr); |
| 400 |
smultscolor(sr.rcol, sr.rcoef); |
| 401 |
saddscolor(np->rp->rcol, sr.rcol); |
| 402 |
} |
| 403 |
++nstaken; |
| 404 |
} |
| 405 |
if (nstarget > 1) { /* final W-G-M-D weighting */ |
| 406 |
smultscolor(scol, sr.rcoef); |
| 407 |
d = (double)nstarget/ntrials; |
| 408 |
scalescolor(scol, d); |
| 409 |
saddscolor(np->rp->rcol, scol); |
| 410 |
} |
| 411 |
ndims--; |
| 412 |
} |
| 413 |
/* compute transmission */ |
| 414 |
copyscolor(sr.rcoef, np->mcolor); /* modify by material color */ |
| 415 |
scalescolor(sr.rcoef, np->tspec); |
| 416 |
if ((np->specfl & (SP_TRAN|SP_TBLT)) == SP_TRAN && |
| 417 |
rayorigin(&sr, TSPECULAR, np->rp, sr.rcoef) == 0) { |
| 418 |
nstarget = 1; |
| 419 |
if (specjitter > 1.5) { /* multiple samples? */ |
| 420 |
nstarget = specjitter*np->rp->rweight + .5; |
| 421 |
if (sr.rweight <= minweight*nstarget) |
| 422 |
nstarget = sr.rweight/minweight; |
| 423 |
if (nstarget > 1) { |
| 424 |
d = 1./nstarget; |
| 425 |
scalescolor(sr.rcoef, d); |
| 426 |
sr.rweight *= d; |
| 427 |
} else |
| 428 |
nstarget = 1; |
| 429 |
} |
| 430 |
dimlist[ndims++] = (int)(size_t)np->mp; |
| 431 |
maxiter = MAXITER*nstarget; |
| 432 |
for (nstaken = ntrials = 0; (nstaken < nstarget) & |
| 433 |
(ntrials < maxiter); ntrials++) { |
| 434 |
if (ntrials) |
| 435 |
d = frandom(); |
| 436 |
else |
| 437 |
d = urand(ilhash(dimlist,ndims)+1823+samplendx); |
| 438 |
multisamp(rv, 2, d); |
| 439 |
d = 2.0*PI * rv[0]; |
| 440 |
cosp = tcos(d) * np->u_alpha; |
| 441 |
sinp = tsin(d) * np->v_alpha; |
| 442 |
d = 1./sqrt(cosp*cosp + sinp*sinp); |
| 443 |
cosp *= d; |
| 444 |
sinp *= d; |
| 445 |
if ((0. <= specjitter) & (specjitter < 1.)) |
| 446 |
rv[1] = 1.0 - specjitter*rv[1]; |
| 447 |
if (rv[1] <= FTINY) |
| 448 |
d = 1.0; |
| 449 |
else |
| 450 |
d = sqrt(-log(rv[1]) / |
| 451 |
(cosp*cosp/(np->u_alpha*np->u_alpha) + |
| 452 |
sinp*sinp/(np->v_alpha*np->v_alpha))); |
| 453 |
for (i = 0; i < 3; i++) |
| 454 |
sr.rdir[i] = np->prdir[i] + |
| 455 |
d*(cosp*np->u[i] + sinp*np->v[i]); |
| 456 |
if (DOT(sr.rdir,np->rp->ron) >= -FTINY) |
| 457 |
continue; /* reject sample */ |
| 458 |
normalize(sr.rdir); /* OK, normalize */ |
| 459 |
if (nstaken) /* multi-sampling */ |
| 460 |
rayclear(&sr); |
| 461 |
rayvalue(&sr); |
| 462 |
smultscolor(sr.rcol, sr.rcoef); |
| 463 |
saddscolor(np->rp->rcol, sr.rcol); |
| 464 |
++nstaken; |
| 465 |
} |
| 466 |
ndims--; |
| 467 |
} |
| 468 |
} |
