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#ifndef lint |
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static const char RCSid[] = "$Id$"; |
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static const char RCSid[] = "$Id$"; |
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#endif |
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/* |
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* glass.c - simpler shading function for thin glass surfaces. |
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#include "copyright.h" |
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#include "ray.h" |
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#include "otypes.h" |
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#include "rtotypes.h" |
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/* |
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* This definition of glass provides for a quick calculation |
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#define RINDEX 1.52 /* refractive index of glass */ |
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m_glass(m, r) /* color a ray which hit a thin glass surface */ |
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OBJREC *m; |
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register RAY *r; |
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extern int |
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m_glass( /* color a ray which hit a thin glass surface */ |
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OBJREC *m, |
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register RAY *r |
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) |
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{ |
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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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int hastexture, hastrans; |
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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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rindex = m->oargs.farg[3]; /* use their value */ |
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else |
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objerror(m, USER, "bad arguments"); |
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/* check transmission */ |
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setcolor(mcolor, m->oargs.farg[0], m->oargs.farg[1], m->oargs.farg[2]); |
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if ((hastrans = (intens(mcolor) > 1e-15))) { |
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for (i = 0; i < 3; i++) |
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if (colval(mcolor,i) < 1e-15) |
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colval(mcolor,i) = 1e-15; |
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} else if (r->crtype & SHADOW) |
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return(1); |
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/* get modifiers */ |
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raytexture(r, m->omod); |
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if (r->rod < 0.0) /* reorient if necessary */ |
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flipsurface(r); |
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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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if (hastexture = DOT(r->pert,r->pert) > FTINY*FTINY) |
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/* perturb normal */ |
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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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} 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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setcolor(mcolor, pow(colval(mcolor,RED), 1.0/cos2), |
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pow(colval(mcolor,GRN), 1.0/cos2), |
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pow(colval(mcolor,BLU), 1.0/cos2)); |
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if (hastrans) |
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setcolor(mcolor, pow(colval(mcolor,RED), 1.0/cos2), |
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pow(colval(mcolor,GRN), 1.0/cos2), |
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pow(colval(mcolor,BLU), 1.0/cos2)); |
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/* compute reflection */ |
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r1e = (pdot - rindex*cos2) / (pdot + rindex*cos2); |
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r1e *= r1e; |
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r1m = (1.0/pdot - rindex/cos2) / (1.0/pdot + rindex/cos2); |
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r1m *= r1m; |
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/* compute transmittance */ |
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for (i = 0; i < 3; i++) { |
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d = colval(mcolor, i); |
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colval(trans,i) = .5*(1.0-r1e)*(1.0-r1e)*d/(1.0-r1e*r1e*d*d); |
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colval(trans,i) += .5*(1.0-r1m)*(1.0-r1m)*d/(1.0-r1m*r1m*d*d); |
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} |
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/* compute transmission */ |
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if (hastrans) { |
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for (i = 0; i < 3; i++) { |
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d = colval(mcolor, i); |
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colval(trans,i) = .5*(1.0-r1e)*(1.0-r1e)*d / |
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(1.0-r1e*r1e*d*d); |
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colval(trans,i) += .5*(1.0-r1m)*(1.0-r1m)*d / |
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(1.0-r1m*r1m*d*d); |
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} |
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multcolor(trans, r->pcol); /* modify by pattern */ |
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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) && hastexture) { |
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for (i = 0; i < 3; i++) /* perturb direction */ |
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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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if (rayorigin(&p, TRANS, r, trans) == 0) { |
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if (!(r->crtype & SHADOW) && hastexture) { |
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VSUM(p.rdir, r->rdir, r->pert, 2.*(1.-rindex)); |
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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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} |
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} else { |
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VCOPY(p.rdir, r->rdir); |
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transtest = 2; |
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rayvalue(&p); |
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multcolor(p.rcol, p.rcoef); |
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addcolor(r->rcol, p.rcol); |
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transtest *= bright(p.rcol); |
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transdist = r->rot + p.rt; |
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} |
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rayvalue(&p); |
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multcolor(p.rcol, r->pcol); /* modify */ |
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multcolor(p.rcol, trans); |
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addcolor(r->rcol, p.rcol); |
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transtest *= bright(p.rcol); |
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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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r->rt = transdist; |
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return(1); |
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colval(refl,i) += .5*r1m*(1.0+(1.0-2.0*r1m)*d)/(1.0-r1m*r1m*d); |
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} |
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/* reflected ray */ |
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if (rayorigin(&p, r, REFLECTED, bright(refl)) == 0) { |
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for (i = 0; i < 3; i++) |
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p.rdir[i] = r->rdir[i] + 2.0*pdot*pnorm[i]; |
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if (rayorigin(&p, REFLECTED, r, refl) == 0) { |
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VSUM(p.rdir, r->rdir, pnorm, 2.*pdot); |
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checknorm(p.rdir); |
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rayvalue(&p); |
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multcolor(p.rcol, refl); |
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multcolor(p.rcol, p.rcoef); |
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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); |
