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#include "ray.h" |
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#include "otypes.h" |
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/* |
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* This definition of glass provides for a quick calculation |
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* using a single surface where two closely spaced parallel |
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* modifier glass id |
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* 0 |
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* 0 |
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* 3 red grn blu |
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* 3+ red grn blu [refractive_index] |
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* |
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* The color is used for the transmission at normal incidence. |
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* To compute transmission (tn) from transmissivity (Tn) use: |
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* To compute transmissivity (tn) from transmittance (Tn) use: |
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* |
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* tn = (sqrt(.8402528435+.0072522239*Tn*Tn)-.9166530661)/.0036261119/Tn |
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* |
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* The transmission of standard 88% transmissivity glass is 0.96. |
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* The transmissivity of standard 88% transmittance glass is 0.96. |
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* A refractive index other than the default can be used by giving |
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* it as the fourth real argument. The above formula no longer applies. |
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* |
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OBJREC *m; |
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register RAY *r; |
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{ |
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double sqrt(), pow(); |
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COLOR mcolor; |
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double pdot; |
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FVECT pnorm; |
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double rindex, cos2; |
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COLOR trans, refl; |
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int hastexture; |
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double d, r1e, r1m; |
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double transtest, transdist; |
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double mirtest, mirdist; |
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RAY p; |
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register int i; |
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/* check arguments */ |
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if (r->rod < 0.0) /* reorient if necessary */ |
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flipsurface(r); |
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transtest = 0; |
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mirtest = transtest = 0; |
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mirdist = transdist = r->rot; |
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/* get modifiers */ |
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raytexture(r, m->omod); |
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pdot = raynormal(pnorm, r); |
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if (hastexture = DOT(r->pert,r->pert) > FTINY*FTINY) |
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pdot = raynormal(pnorm, r); |
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else { |
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VCOPY(pnorm, r->ron); |
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pdot = r->rod; |
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} |
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/* angular transmission */ |
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cos2 = sqrt( (1.0-1.0/(rindex*rindex)) + |
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pdot*pdot/(rindex*rindex) ); |
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} |
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/* transmitted ray */ |
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if (rayorigin(&p, r, TRANS, bright(trans)) == 0) { |
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if (!(r->crtype & SHADOW) && |
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DOT(r->pert,r->pert) > FTINY*FTINY) { |
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if (!(r->crtype & SHADOW) && hastexture) { |
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for (i = 0; i < 3; i++) /* perturb direction */ |
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p.rdir[i] = r->rdir[i] - r->pert[i]/rindex; |
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normalize(p.rdir); |
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p.rdir[i] = r->rdir[i] + |
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2.*(1.-rindex)*r->pert[i]; |
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if (normalize(p.rdir) == 0.0) { |
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objerror(m, WARNING, "bad perturbation"); |
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VCOPY(p.rdir, r->rdir); |
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} |
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} else { |
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VCOPY(p.rdir, r->rdir); |
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transtest = 2; |
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transdist = r->rot + p.rt; |
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} |
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if (r->crtype & SHADOW) /* skip reflected ray */ |
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return; |
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if (r->crtype & SHADOW) { /* skip reflected ray */ |
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r->rt = transdist; |
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return(1); |
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} |
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/* compute reflectance */ |
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for (i = 0; i < 3; i++) { |
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d = colval(mcolor, i); |
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rayvalue(&p); |
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multcolor(p.rcol, refl); |
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addcolor(r->rcol, p.rcol); |
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if (!hastexture && r->ro != NULL && isflat(r->ro->otype)) { |
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mirtest = 2.0*bright(p.rcol); |
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mirdist = r->rot + p.rt; |
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} |
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} |
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if (transtest > bright(r->rcol)) |
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/* check distance */ |
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d = bright(r->rcol); |
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if (transtest > d) |
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r->rt = transdist; |
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else if (mirtest > d) |
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r->rt = mirdist; |
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return(1); |
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} |
