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/* Copyright (c) 1986 Regents of the University of California */ |
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/* Copyright (c) 1998 Silicon Graphics, Inc. */ |
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#ifndef lint |
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static char SCCSid[] = "$SunId$ LBL"; |
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static char SCCSid[] = "$SunId$ SGI"; |
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#endif |
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/* |
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#define MINCOS 0.997 /* minimum dot product for dispersion */ |
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extern COLOR cextinction; /* global coefficient of extinction */ |
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extern COLOR salbedo; /* global scattering albedo */ |
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m_dielectric(m, r) /* color a ray which hit something transparent */ |
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static double |
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mylog(x) /* special log for extinction coefficients */ |
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double x; |
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{ |
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if (x < 1e-40) |
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return(-100.); |
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if (x >= 1.) |
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return(0.); |
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return(log(x)); |
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} |
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m_dielectric(m, r) /* color a ray which hit a dielectric interface */ |
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OBJREC *m; |
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register RAY *r; |
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{ |
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double cos1, cos2, nratio; |
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COLOR mcolor; |
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double mabsorp; |
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COLOR ctrans; |
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COLOR talb; |
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double refl, trans; |
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FVECT dnorm; |
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double d1, d2; |
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dnorm[0] = -dnorm[0]; |
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dnorm[1] = -dnorm[1]; |
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dnorm[2] = -dnorm[2]; |
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setcolor(mcolor, pow(m->oargs.farg[0], r->rot), |
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pow(m->oargs.farg[1], r->rot), |
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pow(m->oargs.farg[2], r->rot)); |
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multcolor(mcolor, r->pcol); /* modify */ |
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setcolor(r->cext, -mylog(m->oargs.farg[0]*colval(r->pcol,RED)), |
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-mylog(m->oargs.farg[1]*colval(r->pcol,GRN)), |
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-mylog(m->oargs.farg[2]*colval(r->pcol,BLU))); |
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setcolor(r->albedo, 0., 0., 0.); |
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r->gecc = 0.; |
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if (m->otype == MAT_INTERFACE) { |
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setcolor(ctrans, |
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-mylog(m->oargs.farg[4]*colval(r->pcol,RED)), |
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-mylog(m->oargs.farg[5]*colval(r->pcol,GRN)), |
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-mylog(m->oargs.farg[6]*colval(r->pcol,BLU))); |
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setcolor(talb, 0., 0., 0.); |
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} else { |
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copycolor(ctrans, cextinction); |
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copycolor(talb, salbedo); |
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} |
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} else { /* outside */ |
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nratio = 1.0 / nratio; |
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if (m->otype == MAT_INTERFACE) |
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setcolor(mcolor, pow(m->oargs.farg[4], r->rot), |
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pow(m->oargs.farg[5], r->rot), |
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pow(m->oargs.farg[6], r->rot)); |
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else |
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setcolor(mcolor, 1.0, 1.0, 1.0); |
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setcolor(ctrans, -mylog(m->oargs.farg[0]*colval(r->pcol,RED)), |
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-mylog(m->oargs.farg[1]*colval(r->pcol,GRN)), |
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-mylog(m->oargs.farg[2]*colval(r->pcol,BLU))); |
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setcolor(talb, 0., 0., 0.); |
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if (m->otype == MAT_INTERFACE) { |
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setcolor(r->cext, |
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-mylog(m->oargs.farg[4]*colval(r->pcol,RED)), |
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-mylog(m->oargs.farg[5]*colval(r->pcol,GRN)), |
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-mylog(m->oargs.farg[6]*colval(r->pcol,BLU))); |
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setcolor(r->albedo, 0., 0., 0.); |
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r->gecc = 0.; |
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} |
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} |
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mabsorp = bright(mcolor); |
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d2 = 1.0 - nratio*nratio*(1.0 - cos1*cos1); /* compute cos theta2 */ |
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d1 = (d1 - d2) / (d1 + d2); |
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refl += d1 * d1; |
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refl /= 2.0; |
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refl *= 0.5; |
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trans = 1.0 - refl; |
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if (rayorigin(&p, r, REFRACTED, mabsorp*trans) == 0) { |
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if (rayorigin(&p, r, REFRACTED, trans) == 0) { |
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/* compute refracted ray */ |
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d1 = nratio*cos1 - cos2; |
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|| r->crtype & SHADOW |
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|| !directvis |
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|| m->oargs.farg[4] == 0.0 |
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|| !disperse(m, r, p.rdir, trans)) |
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|| !disperse(m, r, p.rdir, |
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trans, ctrans, talb)) |
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#endif |
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{ |
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copycolor(p.cext, ctrans); |
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copycolor(p.albedo, talb); |
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rayvalue(&p); |
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scalecolor(p.rcol, trans); |
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addcolor(r->rcol, p.rcol); |
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} |
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if (!(r->crtype & SHADOW) && |
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rayorigin(&p, r, REFLECTED, mabsorp*refl) == 0) { |
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rayorigin(&p, r, REFLECTED, refl) == 0) { |
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/* compute reflected ray */ |
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for (i = 0; i < 3; i++) |
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scalecolor(p.rcol, refl); /* color contribution */ |
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addcolor(r->rcol, p.rcol); |
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} |
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multcolor(r->rcol, mcolor); /* multiply by transmittance */ |
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/* rayvalue() computes absorption */ |
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return(1); |
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} |
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#ifdef DISPERSE |
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static |
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disperse(m, r, vt, tr) /* check light sources for dispersion */ |
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disperse(m, r, vt, tr, cet, abt) /* check light sources for dispersion */ |
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OBJREC *m; |
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RAY *r; |
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FVECT vt; |
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double tr; |
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COLOR cet, abt; |
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{ |
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RAY sray, *entray; |
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FVECT v1, v2, n1, n2; |
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if (l1 > MAXLAMBDA || l1 < MINLAMBDA) /* not visible */ |
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continue; |
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/* trace source ray */ |
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copycolor(sray.cext, cet); |
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copycolor(sray.albedo, abt); |
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normalize(sray.rdir); |
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rayvalue(&sray); |
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if (bright(sray.rcol) <= FTINY) /* missed it */ |
