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#ifndef lint |
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static const char RCSid[] = "$Id: m_mirror.c,v 2.24 2025/05/29 16:42:28 greg Exp $"; |
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#endif |
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/* |
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* Routines for mirror material supporting virtual light sources |
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*/ |
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|
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#include "copyright.h" |
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|
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#include "ray.h" |
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#include "otypes.h" |
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#include "otspecial.h" |
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#include "rtotypes.h" |
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#include "source.h" |
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|
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/* |
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* The real arguments for MAT_MIRROR are simply: |
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* |
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* 3 rrefl grefl brefl |
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* |
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* Additionally, the user may specify a single string argument |
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* which is interpreted as the name of the material to use |
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* instead of the mirror if the ray being considered is not |
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* part of the direct calculation. |
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*/ |
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|
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static int mir_proj(MAT4 pm, OBJREC *o, SRCREC *s, int n); |
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static void mirrorproj(MAT4 m, FVECT nv, double offs); |
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|
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VSMATERIAL mirror_vs = {mir_proj, 1}; |
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|
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|
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int |
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m_mirror( /* shade mirrored ray */ |
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OBJREC *m, |
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RAY *r |
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) |
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{ |
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/* check arguments */ |
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if (m->oargs.nfargs != 3 || m->oargs.nsargs > 1) |
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objerror(m, USER, "bad number of arguments"); |
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/* check for substitute material */ |
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/* but avoid double-counting */ |
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if (m->oargs.nsargs > 0 && |
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(r->rsrc < 0 || source[r->rsrc].so != r->ro)) { |
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int passOK = (r->rod < 0.) | |
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!(r->crtype & (AMBIENT|SPECULAR)); |
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if (strcmp(m->oargs.sarg[0], VOIDID)) { |
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OBJECT altmod = lastmod(objndx(m), m->oargs.sarg[0]); |
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OBJREC *altmat; |
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if (passOK) /* no double-count hazard? */ |
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return(rayshade(r, altmod)); |
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if (altmod == OVOID || /* else check alternate type */ |
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(altmat = findmaterial(objptr(altmod))) == NULL) |
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return(0); |
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if (istransp(altmat)) /* pass "transparent" materials */ |
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return(rayshade(r, altmod)); |
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} else if (passOK) { |
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raytrans(r); /* "safe" void passage */ |
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return(1); |
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} |
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} |
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/* check for bad source ray */ |
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if (r->rsrc >= 0 && source[r->rsrc].so != r->ro) |
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return(1); |
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|
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if (r->rod < 0.) { /* back is black */ |
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if (!backvis) |
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raytrans(r); /* unless back visibility is off */ |
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return(1); |
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} |
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{ /* new context for stack memory */ |
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SCOLOR mcolor; |
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RAY nr; |
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int rpure = 1; |
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int i; |
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/* get modifiers */ |
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raytexture(r, m->omod); |
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/* assign material color */ |
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setscolor(mcolor, m->oargs.farg[0], |
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m->oargs.farg[1], |
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m->oargs.farg[2]); |
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smultscolor(mcolor, r->pcol); |
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/* compute reflected ray */ |
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if (r->rsrc >= 0) { /* relayed light source */ |
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rayorigin(&nr, REFLECTED, r, mcolor); |
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/* ignore textures */ |
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for (i = 0; i < 3; i++) |
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nr.rdir[i] = r->rdir[i] + 2.*r->rod*r->ron[i]; |
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/* source we're aiming for next */ |
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nr.rsrc = source[r->rsrc].sa.sv.sn; |
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} else { /* ordinary reflection */ |
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FVECT pnorm; |
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double pdot; |
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|
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if (rayorigin(&nr, REFLECTED, r, mcolor) < 0) |
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return(1); |
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if (!(r->crtype & AMBIENT) && |
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DOT(r->pert,r->pert) > FTINY*FTINY) { |
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pdot = raynormal(pnorm, r); /* use textures */ |
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for (i = 0; i < 3; i++) |
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nr.rdir[i] = r->rdir[i] + 2.*pdot*pnorm[i]; |
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rpure = 0; |
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} |
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/* check for penetration */ |
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if (rpure || DOT(nr.rdir, r->ron) <= FTINY) |
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for (i = 0; i < 3; i++) |
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nr.rdir[i] = r->rdir[i] + 2.*r->rod*r->ron[i]; |
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} |
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checknorm(nr.rdir); |
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rayvalue(&nr); |
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smultscolor(nr.rcol, nr.rcoef); |
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copyscolor(r->mcol, nr.rcol); |
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saddscolor(r->rcol, nr.rcol); |
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r->rmt = r->rot; |
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if (rpure && r->ro != NULL && isflat(r->ro->otype)) |
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r->rmt += raydistance(&nr); |
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} /* end stack context */ |
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return(1); |
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} |
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|
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|
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static int |
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mir_proj( /* compute a mirror's projection */ |
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MAT4 pm, |
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OBJREC *o, |
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SRCREC *s, |
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int n |
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) |
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{ |
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double corr = 1.; |
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FVECT nv, sc; |
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double od, offs; |
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int i; |
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/* get surface normal and offset */ |
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offs = od = getplaneq(nv, o); |
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if (s->sflags & SDISTANT) |
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offs = 0.; |
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/* check for extreme point behind */ |
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if (s->sflags & SCIR) { |
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if (s->sflags & (SFLAT|SDISTANT)) |
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corr = 1.12837917; /* correct setflatss() */ |
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else |
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corr = 1.0/0.7236; /* correct sphsetsrc() */ |
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} |
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VCOPY(sc, s->sloc); |
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for (i = s->sflags & SFLAT ? SV : SW; i >= 0; i--) |
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if (DOT(nv, s->ss[i]) > offs) |
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VSUM(sc, sc, s->ss[i], corr); |
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else |
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VSUM(sc, sc, s->ss[i], -corr); |
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if (DOT(sc, nv) <= offs+FTINY) |
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return(0); |
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/* everything OK -- compute projection */ |
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mirrorproj(pm, nv, od); |
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return(1); |
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} |
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|
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|
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static void |
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mirrorproj( /* get mirror projection for surface */ |
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MAT4 m, |
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FVECT nv, |
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double offs |
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) |
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{ |
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int i, j; |
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/* assign matrix */ |
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setident4(m); |
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for (j = 0; j < 3; j++) { |
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for (i = 0; i < 3; i++) |
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m[i][j] -= 2.*nv[i]*nv[j]; |
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m[3][j] = 2.*offs*nv[j]; |
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} |
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} |
