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extern double specthresh; /* specular sampling threshold */ |
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extern double specjitter; /* specular sampling jitter */ |
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extern int backvis; /* back faces visible? */ |
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static agaussamp(), getacoords(); |
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/* |
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* This anisotropic reflection model uses a variant on the |
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* exponential Gaussian used in normal.c. |
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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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* 8 red grn blu rspec u-rough v-rough trans tspec |
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*/ |
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|
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#define BSPEC(m) (6.0) /* specularity parameter b */ |
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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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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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normalize(h); |
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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 = (dtmp1 + dtmp2) / (1.0 + DOT(np->pnorm, h)); |
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dtmp = exp(-2.0*dtmp) * (1.0/4.0/PI) |
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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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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*dtmp1 / au2; |
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dtmp1 *= dtmp1 / au2; |
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dtmp2 = DOT(h,np->v); |
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< |
dtmp2 = dtmp2*dtmp2 / av2; |
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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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register RAY *r; |
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{ |
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ANISODAT nd; |
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double dtmp; |
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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; |
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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.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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/* reorient if necessary */ |
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if (r->rod < 0.0) |
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flipsurface(r); |
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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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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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/* improved model */ |
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dtmp = exp(-BSPEC(m)*nd.pdot); |
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for (i = 0; i < 3; i++) |
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colval(nd.scolor,i) += (1.0-colval(nd.scolor,i))*dtmp; |
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– |
nd.rspec += (1.0-nd.rspec)*dtmp; |
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/* check threshold */ |
230 |
< |
if (specthresh > FTINY && |
230 |
< |
(specthresh >= 1.-FTINY || |
231 |
< |
specthresh + .05 - .1*frandom() > nd.rspec)) |
230 |
> |
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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if (nd.tspec > FTINY) { |
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nd.specfl |= SP_TRAN; |
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/* check threshold */ |
247 |
< |
if (specthresh > FTINY && |
249 |
< |
(specthresh >= 1.-FTINY || |
250 |
< |
specthresh + .05 - .1*frandom() > nd.tspec)) |
247 |
> |
if (specthresh >= nd.tspec-FTINY) |
248 |
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nd.specfl |= SP_TBLT; |
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if (DOT(r->pert,r->pert) <= FTINY*FTINY) { |
250 |
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VCOPY(nd.prdir, r->rdir); |
263 |
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/* diffuse reflection */ |
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nd.rdiff = 1.0 - nd.trans - nd.rspec; |
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|
266 |
< |
if (r->ro != NULL && (r->ro->otype == OBJ_FACE || |
270 |
< |
r->ro->otype == OBJ_RING)) |
266 |
> |
if (r->ro != NULL && isflat(r->ro->otype)) |
267 |
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nd.specfl |= SP_FLAT; |
268 |
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|
269 |
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getacoords(r, &nd); /* set up coordinates */ |
293 |
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} |
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/* add direct component */ |
295 |
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direct(r, diraniso, &nd); |
296 |
+ |
|
297 |
+ |
return(1); |
298 |
|
} |
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