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/* Copyright (c) 1991 Regents of the University of California */ |
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#ifndef lint |
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static char SCCSid[] = "$SunId$ LBL"; |
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static const char RCSid[] = "$Id$"; |
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#endif |
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|
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/* |
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* glass.c - simpler shading function for thin glass surfaces. |
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*/ |
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|
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/* ==================================================================== |
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* The Radiance Software License, Version 1.0 |
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* |
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* 11/14/86 |
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* Copyright (c) 1990 - 2002 The Regents of the University of California, |
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* through Lawrence Berkeley National Laboratory. All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions |
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* are met: |
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* |
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* 1. Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* |
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* 2. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in |
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* the documentation and/or other materials provided with the |
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* distribution. |
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* |
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* 3. The end-user documentation included with the redistribution, |
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* if any, must include the following acknowledgment: |
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* "This product includes Radiance software |
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* (http://radsite.lbl.gov/) |
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* developed by the Lawrence Berkeley National Laboratory |
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* (http://www.lbl.gov/)." |
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* Alternately, this acknowledgment may appear in the software itself, |
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* if and wherever such third-party acknowledgments normally appear. |
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* |
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* 4. The names "Radiance," "Lawrence Berkeley National Laboratory" |
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* and "The Regents of the University of California" must |
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* not be used to endorse or promote products derived from this |
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* software without prior written permission. For written |
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* permission, please contact [email protected]. |
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* |
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* 5. Products derived from this software may not be called "Radiance", |
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* nor may "Radiance" appear in their name, without prior written |
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* permission of Lawrence Berkeley National Laboratory. |
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* |
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED |
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
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* DISCLAIMED. IN NO EVENT SHALL Lawrence Berkeley National Laboratory OR |
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* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF |
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* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND |
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, |
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT |
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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* SUCH DAMAGE. |
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* ==================================================================== |
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* |
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* This software consists of voluntary contributions made by many |
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* individuals on behalf of Lawrence Berkeley National Laboratory. For more |
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* information on Lawrence Berkeley National Laboratory, please see |
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* <http://www.lbl.gov/>. |
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*/ |
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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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* If we appear to hit the back side of the surface, then we |
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* turn the normal around. |
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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 cos2; |
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double rindex, cos2; |
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COLOR trans, refl; |
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double d, r1; |
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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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|
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if (m->oargs.nfargs != 3) |
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/* check arguments */ |
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if (m->oargs.nfargs == 3) |
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rindex = RINDEX; /* default value of n */ |
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else if (m->oargs.nfargs == 4) |
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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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|
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setcolor(mcolor, m->oargs.farg[0], m->oargs.farg[1], m->oargs.farg[2]); |
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|
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if (r->rod < 0.0) /* reorient if necessary */ |
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flipsurface(r); |
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r->rt = r->rot; /* default ray length */ |
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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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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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|
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/* compute reflection */ |
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r1 = (pdot - RINDEX*cos2) / (pdot + RINDEX*cos2); |
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d = (1.0/pdot - RINDEX/cos2) / (1.0/pdot + RINDEX/cos2); |
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r1 = (r1*r1 + d*d) / 2.0; |
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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) = (1.0-r1)*(1.0-r1)*d / (1.0 - r1*r1*d*d); |
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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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/* transmitted ray */ |
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if (rayorigin(&p, r, TRANS, bright(trans)) == 0) { |
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if (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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|
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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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d *= d; |
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colval(refl,i) = r1 * (1.0 + (1.0-2.0*r1)*d) / (1.0 - r1*r1*d); |
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colval(refl,i) = .5*r1e*(1.0+(1.0-2.0*r1e)*d)/(1.0-r1e*r1e*d); |
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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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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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} |
