src/rt/raytrace.c

#ifndef lint
static const char       RCSid[] = "$Id$";
#endif
/*
 *  raytrace.c - routines for tracing and shading rays.
 *
 *  External symbols declared in ray.h
 */

/* ====================================================================
 * The Radiance Software License, Version 1.0
 *
 * Copyright (c) 1990 - 2002 The Regents of the University of California,
 * through Lawrence Berkeley National Laboratory.   All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *         notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in
 *       the documentation and/or other materials provided with the
 *       distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *           if any, must include the following acknowledgment:
 *             "This product includes Radiance software
 *                 (http://radsite.lbl.gov/)
 *                 developed by the Lawrence Berkeley National Laboratory
 *               (http://www.lbl.gov/)."
 *       Alternately, this acknowledgment may appear in the software itself,
 *       if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Radiance," "Lawrence Berkeley National Laboratory"
 *       and "The Regents of the University of California" must
 *       not be used to endorse or promote products derived from this
 *       software without prior written permission. For written
 *       permission, please contact [email protected].
 *
 * 5. Products derived from this software may not be called "Radiance",
 *       nor may "Radiance" appear in their name, without prior written
 *       permission of Lawrence Berkeley National Laboratory.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.   IN NO EVENT SHALL Lawrence Berkeley National Laboratory OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of Lawrence Berkeley National Laboratory.   For more
 * information on Lawrence Berkeley National Laboratory, please see
 * <http://www.lbl.gov/>.
 */

#include  "ray.h"

#include  "otypes.h"

#include  "otspecial.h"

#define  MAXCSET        ((MAXSET+1)*2-1)        /* maximum check set size */

unsigned long  raynum = 0;              /* next unique ray number */
unsigned long  nrays = 0;               /* number of calls to localhit */

static FLOAT  Lambfa[5] = {PI, PI, PI, 0.0, 0.0};
OBJREC  Lamb = {
        OVOID, MAT_PLASTIC, "Lambertian",
        {0, 5, NULL, Lambfa}, NULL,
};                                      /* a Lambertian surface */

OBJREC  Aftplane;                       /* aft clipping plane object */

static int  raymove(), checkhit();
static void  checkset();

#ifndef  MAXLOOP
#define  MAXLOOP        0               /* modifier loop detection */
#endif

#define  RAYHIT         (-1)            /* return value for intercepted ray */


int
rayorigin(r, ro, rt, rw)                /* start new ray from old one */
register RAY  *r, *ro;
int  rt;
double  rw;
{
        double  re;

        if ((r->parent = ro) == NULL) {         /* primary ray */
                r->rlvl = 0;
                r->rweight = rw;
                r->crtype = r->rtype = rt;
                r->rsrc = -1;
                r->clipset = NULL;
                r->revf = raytrace;
                copycolor(r->cext, cextinction);
                copycolor(r->albedo, salbedo);
                r->gecc = seccg;
                r->slights = NULL;
        } else {                                /* spawned ray */
                r->rlvl = ro->rlvl;
                if (rt & RAYREFL) {
                        r->rlvl++;
                        r->rsrc = -1;
                        r->clipset = ro->clipset;
                        r->rmax = 0.0;
                } else {
                        r->rsrc = ro->rsrc;
                        r->clipset = ro->newcset;
                        r->rmax = ro->rmax <= FTINY ? 0.0 : ro->rmax - ro->rot;
                }
                r->revf = ro->revf;
                copycolor(r->cext, ro->cext);
                copycolor(r->albedo, ro->albedo);
                r->gecc = ro->gecc;
                r->slights = ro->slights;
                r->crtype = ro->crtype | (r->rtype = rt);
                VCOPY(r->rorg, ro->rop);
                r->rweight = ro->rweight * rw;
                                                /* estimate absorption */
                re = colval(ro->cext,RED) < colval(ro->cext,GRN) ?
                                colval(ro->cext,RED) : colval(ro->cext,GRN);
                if (colval(ro->cext,BLU) < re) re = colval(ro->cext,BLU);
                if (re > 0.)
                        r->rweight *= exp(-re*ro->rot);
        }
        rayclear(r);
        return(r->rlvl <= maxdepth && r->rweight >= minweight ? 0 : -1);
}


void
rayclear(r)                     /* clear a ray for (re)evaluation */
register RAY  *r;
{
        r->rno = raynum++;
        r->newcset = r->clipset;
        r->robj = OVOID;
        r->ro = NULL;
        r->rox = NULL;
        r->rt = r->rot = FHUGE;
        r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
        setcolor(r->pcol, 1.0, 1.0, 1.0);
        setcolor(r->rcol, 0.0, 0.0, 0.0);
}


void
raytrace(r)                     /* trace a ray and compute its value */
RAY  *r;
{
        if (localhit(r, &thescene))
                raycont(r);             /* hit local surface, evaluate */
        else if (r->ro == &Aftplane) {
                r->ro = NULL;           /* hit aft clipping plane */
                r->rot = FHUGE;
        } else if (sourcehit(r))
                rayshade(r, r->ro->omod);       /* distant source */

        rayparticipate(r);              /* for participating medium */

        if (trace != NULL)
                (*trace)(r);            /* trace execution */
}


void
raycont(r)                      /* check for clipped object and continue */
register RAY  *r;
{
        if ((r->clipset != NULL && inset(r->clipset, r->ro->omod)) ||
                        !rayshade(r, r->ro->omod))
                raytrans(r);
}


void
raytrans(r)                     /* transmit ray as is */
register RAY  *r;
{
        RAY  tr;

        if (rayorigin(&tr, r, TRANS, 1.0) == 0) {
                VCOPY(tr.rdir, r->rdir);
                rayvalue(&tr);
                copycolor(r->rcol, tr.rcol);
                r->rt = r->rot + tr.rt;
        }
}


int
rayshade(r, mod)                /* shade ray r with material mod */
register RAY  *r;
int  mod;
{
        int  gotmat;
        register OBJREC  *m;
#if  MAXLOOP
        static int  depth = 0;
                                        /* check for infinite loop */
        if (depth++ >= MAXLOOP)
                objerror(r->ro, USER, "possible modifier loop");
#endif
        r->rt = r->rot;                 /* set effective ray length */
        for (gotmat = 0; !gotmat && mod != OVOID; mod = m->omod) {
                m = objptr(mod);
                /****** unnecessary test since modifier() is always called
                if (!ismodifier(m->otype)) {
                        sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
                        error(USER, errmsg);
                }
                ******/
                                        /* hack for irradiance calculation */
                if (do_irrad && !(r->crtype & ~(PRIMARY|TRANS))) {
                        if (irr_ignore(m->otype)) {
#if  MAXLOOP
                                depth--;
#endif
                                raytrans(r);
                                return(1);
                        }
                        if (!islight(m->otype))
                                m = &Lamb;
                }
                                        /* materials call raytexture */
                gotmat = (*ofun[m->otype].funp)(m, r);
        }
#if  MAXLOOP
        depth--;
#endif
        return(gotmat);
}


void
rayparticipate(r)                       /* compute ray medium participation */
register RAY  *r;
{
        COLOR   ce, ca;
        double  re, ge, be;

        if (intens(r->cext) <= 1./FHUGE)
                return;                         /* no medium */
        re = r->rot*colval(r->cext,RED);
        ge = r->rot*colval(r->cext,GRN);
        be = r->rot*colval(r->cext,BLU);
        if (r->crtype & SHADOW) {               /* no scattering for sources */
                re *= 1. - colval(r->albedo,RED);
                ge *= 1. - colval(r->albedo,GRN);
                be *= 1. - colval(r->albedo,BLU);
        }
        setcolor(ce,    re<=0. ? 1. : re>92. ? 0. : exp(-re),
                        ge<=0. ? 1. : ge>92. ? 0. : exp(-ge),
                        be<=0. ? 1. : be>92. ? 0. : exp(-be));
        multcolor(r->rcol, ce);                 /* path absorption */
        if (r->crtype & SHADOW || intens(r->albedo) <= FTINY)
                return;                         /* no scattering */
        setcolor(ca,
                colval(r->albedo,RED)*colval(ambval,RED)*(1.-colval(ce,RED)),
                colval(r->albedo,GRN)*colval(ambval,GRN)*(1.-colval(ce,GRN)),
                colval(r->albedo,BLU)*colval(ambval,BLU)*(1.-colval(ce,BLU)));
        addcolor(r->rcol, ca);                  /* ambient in scattering */
        srcscatter(r);                          /* source in scattering */
}


raytexture(r, mod)                      /* get material modifiers */
RAY  *r;
int  mod;
{
        register OBJREC  *m;
#if  MAXLOOP
        static int  depth = 0;
                                        /* check for infinite loop */
        if (depth++ >= MAXLOOP)
                objerror(r->ro, USER, "modifier loop");
#endif
                                        /* execute textures and patterns */
        for ( ; mod != OVOID; mod = m->omod) {
                m = objptr(mod);
                /****** unnecessary test since modifier() is always called
                if (!ismodifier(m->otype)) {
                        sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
                        error(USER, errmsg);
                }
                ******/
                if ((*ofun[m->otype].funp)(m, r)) {
                        sprintf(errmsg, "conflicting material \"%s\"",
                                        m->oname);
                        objerror(r->ro, USER, errmsg);
                }
        }
#if  MAXLOOP
        depth--;                        /* end here */
#endif
}


int
raymixture(r, fore, back, coef)         /* mix modifiers */
register RAY  *r;
OBJECT  fore, back;
double  coef;
{
        RAY  fr, br;
        int  foremat, backmat;
        register int  i;
                                        /* bound coefficient */
        if (coef > 1.0)
                coef = 1.0;
        else if (coef < 0.0)
                coef = 0.0;
                                        /* compute foreground and background */
        foremat = backmat = 0;
                                        /* foreground */
        copystruct(&fr, r);
        if (coef > FTINY)
                foremat = rayshade(&fr, fore);
                                        /* background */
        copystruct(&br, r);
        if (coef < 1.0-FTINY)
                backmat = rayshade(&br, back);
                                        /* check for transparency */
        if (backmat ^ foremat)
                if (backmat && coef > FTINY)
                        raytrans(&fr);
                else if (foremat && coef < 1.0-FTINY)
                        raytrans(&br);
                                        /* mix perturbations */
        for (i = 0; i < 3; i++)
                r->pert[i] = coef*fr.pert[i] + (1.0-coef)*br.pert[i];
                                        /* mix pattern colors */
        scalecolor(fr.pcol, coef);
        scalecolor(br.pcol, 1.0-coef);
        copycolor(r->pcol, fr.pcol);
        addcolor(r->pcol, br.pcol);
                                        /* return value tells if material */
        if (!foremat & !backmat)
                return(0);
                                        /* mix returned ray values */
        scalecolor(fr.rcol, coef);
        scalecolor(br.rcol, 1.0-coef);
        copycolor(r->rcol, fr.rcol);
        addcolor(r->rcol, br.rcol);
        r->rt = bright(fr.rcol) > bright(br.rcol) ? fr.rt : br.rt;
        return(1);
}


double
raydist(r, flags)               /* compute (cumulative) ray distance */
register RAY  *r;
register int  flags;
{
        double  sum = 0.0;

        while (r != NULL && r->crtype&flags) {
                sum += r->rot;
                r = r->parent;
        }
        return(sum);
}


double
raynormal(norm, r)              /* compute perturbed normal for ray */
FVECT  norm;
register RAY  *r;
{
        double  newdot;
        register int  i;

        /*      The perturbation is added to the surface normal to obtain
         *  the new normal.  If the new normal would affect the surface
         *  orientation wrt. the ray, a correction is made.  The method is
         *  still fraught with problems since reflected rays and similar
         *  directions calculated from the surface normal may spawn rays behind
         *  the surface.  The only solution is to curb textures at high
         *  incidence (namely, keep DOT(rdir,pert) < Rdot).
         */

        for (i = 0; i < 3; i++)
                norm[i] = r->ron[i] + r->pert[i];

        if (normalize(norm) == 0.0) {
                objerror(r->ro, WARNING, "illegal normal perturbation");
                VCOPY(norm, r->ron);
                return(r->rod);
        }
        newdot = -DOT(norm, r->rdir);
        if ((newdot > 0.0) != (r->rod > 0.0)) {         /* fix orientation */
                for (i = 0; i < 3; i++)
                        norm[i] += 2.0*newdot*r->rdir[i];
                newdot = -newdot;
        }
        return(newdot);
}


void
newrayxf(r)                     /* get new tranformation matrix for ray */
RAY  *r;
{
        static struct xfn {
                struct xfn  *next;
                FULLXF  xf;
        }  xfseed = { &xfseed }, *xflast = &xfseed;
        register struct xfn  *xp;
        register RAY  *rp;

        /*
         * Search for transform in circular list that
         * has no associated ray in the tree.
         */
        xp = xflast;
        for (rp = r->parent; rp != NULL; rp = rp->parent)
                if (rp->rox == &xp->xf) {               /* xp in use */
                        xp = xp->next;                  /* move to next */
                        if (xp == xflast) {             /* need new one */
                                xp = (struct xfn *)malloc(sizeof(struct xfn));
                                if (xp == NULL)
                                        error(SYSTEM,
                                                "out of memory in newrayxf");
                                                        /* insert in list */
                                xp->next = xflast->next;
                                xflast->next = xp;
                                break;                  /* we're done */
                        }
                        rp = r;                 /* start check over */
                }
                                        /* got it */
        r->rox = &xp->xf;
        xflast = xp;
}


void
flipsurface(r)                  /* reverse surface orientation */
register RAY  *r;
{
        r->rod = -r->rod;
        r->ron[0] = -r->ron[0];
        r->ron[1] = -r->ron[1];
        r->ron[2] = -r->ron[2];
        r->pert[0] = -r->pert[0];
        r->pert[1] = -r->pert[1];
        r->pert[2] = -r->pert[2];
}


int
localhit(r, scene)              /* check for hit in the octree */
register RAY  *r;
register CUBE  *scene;
{
        OBJECT  cxset[MAXCSET+1];       /* set of checked objects */
        FVECT  curpos;                  /* current cube position */
        int  sflags;                    /* sign flags */
        double  t, dt;
        register int  i;

        nrays++;                        /* increment trace counter */
        sflags = 0;
        for (i = 0; i < 3; i++) {
                curpos[i] = r->rorg[i];
                if (r->rdir[i] > 1e-7)
                        sflags |= 1 << i;
                else if (r->rdir[i] < -1e-7)
                        sflags |= 0x10 << i;
        }
        if (sflags == 0)
                error(CONSISTENCY, "zero ray direction in localhit");
                                        /* start off assuming nothing hit */
        if (r->rmax > FTINY) {          /* except aft plane if one */
                r->ro = &Aftplane;
                r->rot = r->rmax;
                for (i = 0; i < 3; i++)
                        r->rop[i] = r->rorg[i] + r->rot*r->rdir[i];
        }
                                        /* find global cube entrance point */
        t = 0.0;
        if (!incube(scene, curpos)) {
                                        /* find distance to entry */
                for (i = 0; i < 3; i++) {
                                        /* plane in our direction */
                        if (sflags & 1<<i)
                                dt = scene->cuorg[i];
                        else if (sflags & 0x10<<i)
                                dt = scene->cuorg[i] + scene->cusize;
                        else
                                continue;
                                        /* distance to the plane */
                        dt = (dt - r->rorg[i])/r->rdir[i];
                        if (dt > t)
                                t = dt; /* farthest face is the one */
                }
                t += FTINY;             /* fudge to get inside cube */
                if (t >= r->rot)        /* clipped already */
                        return(0);
                                        /* advance position */
                for (i = 0; i < 3; i++)
                        curpos[i] += r->rdir[i]*t;

                if (!incube(scene, curpos))     /* non-intersecting ray */
                        return(0);
        }
        cxset[0] = 0;
        raymove(curpos, cxset, sflags, r, scene);
        return(r->ro != NULL & r->ro != &Aftplane);
}


static int
raymove(pos, cxs, dirf, r, cu)          /* check for hit as we move */
FVECT  pos;                     /* current position, modified herein */
OBJECT  *cxs;                   /* checked objects, modified by checkhit */
int  dirf;                      /* direction indicators to speed tests */
register RAY  *r;
register CUBE  *cu;
{
        int  ax;
        double  dt, t;

        if (istree(cu->cutree)) {               /* recurse on subcubes */
                CUBE  cukid;
                register int  br, sgn;

                cukid.cusize = cu->cusize * 0.5;        /* find subcube */
                VCOPY(cukid.cuorg, cu->cuorg);
                br = 0;
                if (pos[0] >= cukid.cuorg[0]+cukid.cusize) {
                        cukid.cuorg[0] += cukid.cusize;
                        br |= 1;
                }
                if (pos[1] >= cukid.cuorg[1]+cukid.cusize) {
                        cukid.cuorg[1] += cukid.cusize;
                        br |= 2;
                }
                if (pos[2] >= cukid.cuorg[2]+cukid.cusize) {
                        cukid.cuorg[2] += cukid.cusize;
                        br |= 4;
                }
                for ( ; ; ) {
                        cukid.cutree = octkid(cu->cutree, br);
                        if ((ax = raymove(pos,cxs,dirf,r,&cukid)) == RAYHIT)
                                return(RAYHIT);
                        sgn = 1 << ax;
                        if (sgn & dirf)                 /* positive axis? */
                                if (sgn & br)
                                        return(ax);     /* overflow */
                                else {
                                        cukid.cuorg[ax] += cukid.cusize;
                                        br |= sgn;
                                }
                        else
                                if (sgn & br) {
                                        cukid.cuorg[ax] -= cukid.cusize;
                                        br &= ~sgn;
                                } else
                                        return(ax);     /* underflow */
                }
                /*NOTREACHED*/
        }
        if (isfull(cu->cutree)) {
                if (checkhit(r, cu, cxs))
                        return(RAYHIT);
        } else if (r->ro == &Aftplane && incube(cu, r->rop))
                return(RAYHIT);
                                        /* advance to next cube */
        if (dirf&0x11) {
                dt = dirf&1 ? cu->cuorg[0] + cu->cusize : cu->cuorg[0];
                t = (dt - pos[0])/r->rdir[0];
                ax = 0;
        } else
                t = FHUGE;
        if (dirf&0x22) {
                dt = dirf&2 ? cu->cuorg[1] + cu->cusize : cu->cuorg[1];
                dt = (dt - pos[1])/r->rdir[1];
                if (dt < t) {
                        t = dt;
                        ax = 1;
                }
        }
        if (dirf&0x44) {
                dt = dirf&4 ? cu->cuorg[2] + cu->cusize : cu->cuorg[2];
                dt = (dt - pos[2])/r->rdir[2];
                if (dt < t) {
                        t = dt;
                        ax = 2;
                }
        }
        pos[0] += r->rdir[0]*t;
        pos[1] += r->rdir[1]*t;
        pos[2] += r->rdir[2]*t;
        return(ax);
}


static int
checkhit(r, cu, cxs)            /* check for hit in full cube */
register RAY  *r;
CUBE  *cu;
OBJECT  *cxs;
{
        OBJECT  oset[MAXSET+1];
        register OBJREC  *o;
        register int  i;

        objset(oset, cu->cutree);
        checkset(oset, cxs);                    /* eliminate double-checking */
        for (i = oset[0]; i > 0; i--) {
                o = objptr(oset[i]);
                if ((*ofun[o->otype].funp)(o, r))
                        r->robj = oset[i];
        }
        if (r->ro == NULL)
                return(0);                      /* no scores yet */

        return(incube(cu, r->rop));             /* hit OK if in current cube */
}


static void
checkset(os, cs)                /* modify checked set and set to check */
register OBJECT  *os;                   /* os' = os - cs */
register OBJECT  *cs;                   /* cs' = cs + os */
{
        OBJECT  cset[MAXCSET+MAXSET+1];
        register int  i, j;
        int  k;
                                        /* copy os in place, cset <- cs */
        cset[0] = 0;
        k = 0;
        for (i = j = 1; i <= os[0]; i++) {
                while (j <= cs[0] && cs[j] < os[i])
                        cset[++cset[0]] = cs[j++];
                if (j > cs[0] || os[i] != cs[j]) {      /* object to check */
                        os[++k] = os[i];
                        cset[++cset[0]] = os[i];
                }
        }
        if (!(os[0] = k))               /* new "to check" set size */
                return;                 /* special case */
        while (j <= cs[0])              /* get the rest of cs */
                cset[++cset[0]] = cs[j++];
        if (cset[0] > MAXCSET)          /* truncate "checked" set if nec. */
                cset[0] = MAXCSET;
        /* setcopy(cs, cset); */        /* copy cset back to cs */
        os = cset;
        for (i = os[0]; i-- >= 0; )
                *cs++ = *os++;
}
Revision:	2.34
Committed:	Sat Feb 22 02:07:29 2003 UTC (21 years, 2 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.33:	+76 -24 lines
Log Message:	Changes and check-in for 3.5 release Includes new source files and modifications not recorded for many years See ray/doc/notes/ReleaseNotes for notes between 3.1 and 3.5 release
#	User	Rev	Content
1	greg	1.1	#ifndef lint
2	greg	2.34	static const char RCSid[] = "$Id$";
3	greg	1.1	#endif
4			/*
5			* raytrace.c - routines for tracing and shading rays.
6			*
7	greg	2.34	* External symbols declared in ray.h
8			*/
9
10			/* ====================================================================
11			* The Radiance Software License, Version 1.0
12			*
13			* Copyright (c) 1990 - 2002 The Regents of the University of California,
14			* through Lawrence Berkeley National Laboratory. All rights reserved.
15			*
16			* Redistribution and use in source and binary forms, with or without
17			* modification, are permitted provided that the following conditions
18			* are met:
19			*
20			* 1. Redistributions of source code must retain the above copyright
21			* notice, this list of conditions and the following disclaimer.
22			*
23			* 2. Redistributions in binary form must reproduce the above copyright
24			* notice, this list of conditions and the following disclaimer in
25			* the documentation and/or other materials provided with the
26			* distribution.
27			*
28			* 3. The end-user documentation included with the redistribution,
29			* if any, must include the following acknowledgment:
30			* "This product includes Radiance software
31			* (http://radsite.lbl.gov/)
32			* developed by the Lawrence Berkeley National Laboratory
33			* (http://www.lbl.gov/)."
34			* Alternately, this acknowledgment may appear in the software itself,
35			* if and wherever such third-party acknowledgments normally appear.
36			*
37			* 4. The names "Radiance," "Lawrence Berkeley National Laboratory"
38			* and "The Regents of the University of California" must
39			* not be used to endorse or promote products derived from this
40			* software without prior written permission. For written
41			* permission, please contact [email protected].
42			*
43			* 5. Products derived from this software may not be called "Radiance",
44			* nor may "Radiance" appear in their name, without prior written
45			* permission of Lawrence Berkeley National Laboratory.
46			*
47			* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
48			* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
49			* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
50			* DISCLAIMED. IN NO EVENT SHALL Lawrence Berkeley National Laboratory OR
51			* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
52			* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
53			* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
54			* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
55			* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
56			* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
57			* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
58			* SUCH DAMAGE.
59			* ====================================================================
60			*
61			* This software consists of voluntary contributions made by many
62			* individuals on behalf of Lawrence Berkeley National Laboratory. For more
63			* information on Lawrence Berkeley National Laboratory, please see
64			* <http://www.lbl.gov/>.
65	greg	1.1	*/
66
67			#include "ray.h"
68
69			#include "otypes.h"
70
71	greg	1.15	#include "otspecial.h"
72
73	greg	2.3	#define MAXCSET ((MAXSET+1)2-1) / maximum check set size */
74
75	greg	2.6	unsigned long raynum = 0; /* next unique ray number */
76			unsigned long nrays = 0; /* number of calls to localhit */
77	greg	1.1
78	greg	1.23	static FLOAT Lambfa[5] = {PI, PI, PI, 0.0, 0.0};
79	greg	1.15	OBJREC Lamb = {
80			OVOID, MAT_PLASTIC, "Lambertian",
81	greg	2.2	{0, 5, NULL, Lambfa}, NULL,
82	greg	1.15	}; /* a Lambertian surface */
83
84	greg	2.17	OBJREC Aftplane; /* aft clipping plane object */
85	greg	2.16
86	greg	2.34	static int raymove(), checkhit();
87			static void checkset();
88	greg	2.5
89	gwlarson	2.33	#ifndef MAXLOOP
90			#define MAXLOOP 0 /* modifier loop detection */
91			#endif
92	greg	1.1
93			#define RAYHIT (-1) /* return value for intercepted ray */
94
95
96	greg	2.34	int
97	greg	1.1	rayorigin(r, ro, rt, rw) /* start new ray from old one */
98			register RAY r, ro;
99			int rt;
100			double rw;
101			{
102	gwlarson	2.31	double re;
103
104	greg	1.1	if ((r->parent = ro) == NULL) { /* primary ray */
105			r->rlvl = 0;
106			r->rweight = rw;
107			r->crtype = r->rtype = rt;
108			r->rsrc = -1;
109			r->clipset = NULL;
110	greg	1.21	r->revf = raytrace;
111	greg	2.23	copycolor(r->cext, cextinction);
112	greg	2.26	copycolor(r->albedo, salbedo);
113	greg	2.23	r->gecc = seccg;
114			r->slights = NULL;
115	greg	1.1	} else { /* spawned ray */
116			r->rlvl = ro->rlvl;
117			if (rt & RAYREFL) {
118			r->rlvl++;
119			r->rsrc = -1;
120			r->clipset = ro->clipset;
121	greg	2.22	r->rmax = 0.0;
122	greg	1.1	} else {
123			r->rsrc = ro->rsrc;
124			r->clipset = ro->newcset;
125	greg	2.22	r->rmax = ro->rmax <= FTINY ? 0.0 : ro->rmax - ro->rot;
126	greg	1.1	}
127	greg	1.21	r->revf = ro->revf;
128	greg	2.23	copycolor(r->cext, ro->cext);
129	greg	2.26	copycolor(r->albedo, ro->albedo);
130	greg	2.23	r->gecc = ro->gecc;
131			r->slights = ro->slights;
132	greg	1.1	r->crtype = ro->crtype \| (r->rtype = rt);
133			VCOPY(r->rorg, ro->rop);
134	gwlarson	2.31	r->rweight = ro->rweight * rw;
135			/* estimate absorption */
136			re = colval(ro->cext,RED) < colval(ro->cext,GRN) ?
137			colval(ro->cext,RED) : colval(ro->cext,GRN);
138			if (colval(ro->cext,BLU) < re) re = colval(ro->cext,BLU);
139			if (re > 0.)
140			r->rweight = exp(-rero->rot);
141	greg	1.1	}
142	greg	1.22	rayclear(r);
143			return(r->rlvl <= maxdepth && r->rweight >= minweight ? 0 : -1);
144			}
145
146
147	greg	2.34	void
148	greg	1.22	rayclear(r) /* clear a ray for (re)evaluation */
149			register RAY *r;
150			{
151	greg	1.20	r->rno = raynum++;
152	greg	1.1	r->newcset = r->clipset;
153	greg	2.28	r->robj = OVOID;
154	greg	2.17	r->ro = NULL;
155	greg	2.34	r->rox = NULL;
156	gregl	2.29	r->rt = r->rot = FHUGE;
157	greg	1.1	r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
158			setcolor(r->pcol, 1.0, 1.0, 1.0);
159			setcolor(r->rcol, 0.0, 0.0, 0.0);
160			}
161
162
163	greg	2.34	void
164	greg	1.21	raytrace(r) /* trace a ray and compute its value */
165	greg	1.8	RAY *r;
166	greg	1.1	{
167	greg	1.15	if (localhit(r, &thescene))
168	greg	2.24	raycont(r); /* hit local surface, evaluate */
169	greg	2.16	else if (r->ro == &Aftplane) {
170	greg	2.23	r->ro = NULL; /* hit aft clipping plane */
171	greg	2.16	r->rot = FHUGE;
172			} else if (sourcehit(r))
173	greg	2.24	rayshade(r, r->ro->omod); /* distant source */
174	greg	1.1
175	greg	2.23	rayparticipate(r); /* for participating medium */
176
177	greg	1.1	if (trace != NULL)
178			(trace)(r); / trace execution */
179			}
180
181
182	greg	2.34	void
183	greg	1.8	raycont(r) /* check for clipped object and continue */
184			register RAY *r;
185			{
186	greg	2.7	if ((r->clipset != NULL && inset(r->clipset, r->ro->omod)) \|\|
187	greg	2.24	!rayshade(r, r->ro->omod))
188	greg	1.8	raytrans(r);
189			}
190
191
192	greg	2.34	void
193	greg	1.1	raytrans(r) /* transmit ray as is */
194	greg	1.8	register RAY *r;
195	greg	1.1	{
196			RAY tr;
197
198			if (rayorigin(&tr, r, TRANS, 1.0) == 0) {
199			VCOPY(tr.rdir, r->rdir);
200			rayvalue(&tr);
201			copycolor(r->rcol, tr.rcol);
202	greg	1.10	r->rt = r->rot + tr.rt;
203	greg	1.1	}
204			}
205
206
207	greg	2.34	int
208	greg	1.1	rayshade(r, mod) /* shade ray r with material mod */
209			register RAY *r;
210			int mod;
211			{
212	greg	2.9	int gotmat;
213	greg	1.1	register OBJREC *m;
214	gwlarson	2.33	#if MAXLOOP
215			static int depth = 0;
216	greg	1.1	/* check for infinite loop */
217			if (depth++ >= MAXLOOP)
218	greg	1.4	objerror(r->ro, USER, "possible modifier loop");
219	gwlarson	2.33	#endif
220	greg	1.19	r->rt = r->rot; /* set effective ray length */
221	greg	2.9	for (gotmat = 0; !gotmat && mod != OVOID; mod = m->omod) {
222	greg	1.1	m = objptr(mod);
223	greg	1.4	/****** unnecessary test since modifier() is always called
224	greg	1.1	if (!ismodifier(m->otype)) {
225			sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
226			error(USER, errmsg);
227			}
228	greg	1.4	******/
229	greg	1.16	/* hack for irradiance calculation */
230			if (do_irrad && !(r->crtype & ~(PRIMARY\|TRANS))) {
231			if (irr_ignore(m->otype)) {
232	gwlarson	2.33	#if MAXLOOP
233	greg	1.16	depth--;
234	gwlarson	2.33	#endif
235	greg	1.16	raytrans(r);
236	greg	2.15	return(1);
237	greg	1.16	}
238	greg	1.18	if (!islight(m->otype))
239	greg	1.16	m = &Lamb;
240			}
241	greg	2.9	/* materials call raytexture */
242			gotmat = (*ofun[m->otype].funp)(m, r);
243	greg	1.1	}
244	gwlarson	2.33	#if MAXLOOP
245	greg	2.9	depth--;
246	gwlarson	2.33	#endif
247	greg	2.9	return(gotmat);
248	greg	2.23	}
249
250
251	greg	2.34	void
252	greg	2.23	rayparticipate(r) /* compute ray medium participation */
253			register RAY *r;
254			{
255			COLOR ce, ca;
256			double re, ge, be;
257
258			if (intens(r->cext) <= 1./FHUGE)
259			return; /* no medium */
260	greg	2.27	re = r->rot*colval(r->cext,RED);
261			ge = r->rot*colval(r->cext,GRN);
262			be = r->rot*colval(r->cext,BLU);
263	greg	2.26	if (r->crtype & SHADOW) { /* no scattering for sources */
264			re *= 1. - colval(r->albedo,RED);
265			ge *= 1. - colval(r->albedo,GRN);
266			be *= 1. - colval(r->albedo,BLU);
267			}
268			setcolor(ce, re<=0. ? 1. : re>92. ? 0. : exp(-re),
269			ge<=0. ? 1. : ge>92. ? 0. : exp(-ge),
270			be<=0. ? 1. : be>92. ? 0. : exp(-be));
271	greg	2.23	multcolor(r->rcol, ce); /* path absorption */
272	greg	2.26	if (r->crtype & SHADOW \|\| intens(r->albedo) <= FTINY)
273	greg	2.23	return; /* no scattering */
274	greg	2.26	setcolor(ca,
275			colval(r->albedo,RED)colval(ambval,RED)(1.-colval(ce,RED)),
276			colval(r->albedo,GRN)colval(ambval,GRN)(1.-colval(ce,GRN)),
277			colval(r->albedo,BLU)colval(ambval,BLU)(1.-colval(ce,BLU)));
278	greg	2.23	addcolor(r->rcol, ca); /* ambient in scattering */
279			srcscatter(r); /* source in scattering */
280	greg	1.1	}
281
282
283			raytexture(r, mod) /* get material modifiers */
284			RAY *r;
285			int mod;
286			{
287	gwlarson	2.33	register OBJREC *m;
288			#if MAXLOOP
289	greg	1.1	static int depth = 0;
290			/* check for infinite loop */
291			if (depth++ >= MAXLOOP)
292			objerror(r->ro, USER, "modifier loop");
293	gwlarson	2.33	#endif
294	greg	1.1	/* execute textures and patterns */
295			for ( ; mod != OVOID; mod = m->omod) {
296			m = objptr(mod);
297	greg	2.9	/****** unnecessary test since modifier() is always called
298			if (!ismodifier(m->otype)) {
299	greg	1.1	sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
300			error(USER, errmsg);
301			}
302	greg	2.9	******/
303	greg	2.20	if ((*ofun[m->otype].funp)(m, r)) {
304			sprintf(errmsg, "conflicting material \"%s\"",
305			m->oname);
306			objerror(r->ro, USER, errmsg);
307			}
308	greg	1.1	}
309	gwlarson	2.33	#if MAXLOOP
310	greg	1.1	depth--; /* end here */
311	gwlarson	2.33	#endif
312	greg	1.1	}
313
314
315	greg	2.34	int
316	greg	1.1	raymixture(r, fore, back, coef) /* mix modifiers */
317			register RAY *r;
318			OBJECT fore, back;
319			double coef;
320			{
321	greg	2.9	RAY fr, br;
322			int foremat, backmat;
323	greg	1.1	register int i;
324	greg	2.24	/* bound coefficient */
325	greg	1.1	if (coef > 1.0)
326			coef = 1.0;
327			else if (coef < 0.0)
328			coef = 0.0;
329	greg	2.13	/* compute foreground and background */
330	greg	2.24	foremat = backmat = 0;
331	greg	2.9	/* foreground */
332			copystruct(&fr, r);
333	greg	2.24	if (coef > FTINY)
334	greg	2.9	foremat = rayshade(&fr, fore);
335			/* background */
336			copystruct(&br, r);
337	greg	2.24	if (coef < 1.0-FTINY)
338	greg	2.9	backmat = rayshade(&br, back);
339	greg	2.24	/* check for transparency */
340			if (backmat ^ foremat)
341	gwlarson	2.33	if (backmat && coef > FTINY)
342	greg	2.24	raytrans(&fr);
343	gwlarson	2.33	else if (foremat && coef < 1.0-FTINY)
344	greg	2.24	raytrans(&br);
345	greg	2.12	/* mix perturbations */
346	greg	1.1	for (i = 0; i < 3; i++)
347	greg	2.12	r->pert[i] = coeffr.pert[i] + (1.0-coef)br.pert[i];
348			/* mix pattern colors */
349	greg	2.9	scalecolor(fr.pcol, coef);
350			scalecolor(br.pcol, 1.0-coef);
351	greg	2.12	copycolor(r->pcol, fr.pcol);
352			addcolor(r->pcol, br.pcol);
353	greg	2.24	/* return value tells if material */
354			if (!foremat & !backmat)
355			return(0);
356	greg	2.12	/* mix returned ray values */
357	greg	2.24	scalecolor(fr.rcol, coef);
358			scalecolor(br.rcol, 1.0-coef);
359			copycolor(r->rcol, fr.rcol);
360			addcolor(r->rcol, br.rcol);
361			r->rt = bright(fr.rcol) > bright(br.rcol) ? fr.rt : br.rt;
362			return(1);
363	greg	1.1	}
364
365
366			double
367	greg	2.21	raydist(r, flags) /* compute (cumulative) ray distance */
368			register RAY *r;
369			register int flags;
370			{
371			double sum = 0.0;
372
373			while (r != NULL && r->crtype&flags) {
374			sum += r->rot;
375			r = r->parent;
376			}
377			return(sum);
378			}
379
380
381			double
382	greg	1.1	raynormal(norm, r) /* compute perturbed normal for ray */
383			FVECT norm;
384			register RAY *r;
385			{
386			double newdot;
387			register int i;
388
389			/* The perturbation is added to the surface normal to obtain
390			* the new normal. If the new normal would affect the surface
391			* orientation wrt. the ray, a correction is made. The method is
392			* still fraught with problems since reflected rays and similar
393			* directions calculated from the surface normal may spawn rays behind
394			* the surface. The only solution is to curb textures at high
395	greg	1.9	* incidence (namely, keep DOT(rdir,pert) < Rdot).
396	greg	1.1	*/
397
398			for (i = 0; i < 3; i++)
399			norm[i] = r->ron[i] + r->pert[i];
400
401			if (normalize(norm) == 0.0) {
402			objerror(r->ro, WARNING, "illegal normal perturbation");
403			VCOPY(norm, r->ron);
404			return(r->rod);
405			}
406			newdot = -DOT(norm, r->rdir);
407			if ((newdot > 0.0) != (r->rod > 0.0)) { /* fix orientation */
408			for (i = 0; i < 3; i++)
409			norm[i] += 2.0newdotr->rdir[i];
410			newdot = -newdot;
411			}
412			return(newdot);
413	greg	1.12	}
414
415
416	greg	2.34	void
417	greg	1.12	newrayxf(r) /* get new tranformation matrix for ray */
418			RAY *r;
419			{
420			static struct xfn {
421			struct xfn *next;
422			FULLXF xf;
423			} xfseed = { &xfseed }, *xflast = &xfseed;
424			register struct xfn *xp;
425			register RAY *rp;
426
427			/*
428			* Search for transform in circular list that
429			* has no associated ray in the tree.
430			*/
431			xp = xflast;
432			for (rp = r->parent; rp != NULL; rp = rp->parent)
433			if (rp->rox == &xp->xf) { /* xp in use */
434			xp = xp->next; /* move to next */
435			if (xp == xflast) { /* need new one */
436	greg	2.34	xp = (struct xfn *)malloc(sizeof(struct xfn));
437	greg	1.12	if (xp == NULL)
438			error(SYSTEM,
439			"out of memory in newrayxf");
440			/* insert in list */
441			xp->next = xflast->next;
442			xflast->next = xp;
443			break; /* we're done */
444			}
445			rp = r; /* start check over */
446			}
447			/* got it */
448			r->rox = &xp->xf;
449			xflast = xp;
450	greg	1.1	}
451
452
453	greg	2.34	void
454	greg	1.1	flipsurface(r) /* reverse surface orientation */
455			register RAY *r;
456			{
457			r->rod = -r->rod;
458			r->ron[0] = -r->ron[0];
459			r->ron[1] = -r->ron[1];
460			r->ron[2] = -r->ron[2];
461			r->pert[0] = -r->pert[0];
462			r->pert[1] = -r->pert[1];
463			r->pert[2] = -r->pert[2];
464			}
465
466
467	greg	2.34	int
468	greg	1.1	localhit(r, scene) /* check for hit in the octree */
469			register RAY *r;
470			register CUBE *scene;
471			{
472	greg	2.3	OBJECT cxset[MAXCSET+1]; /* set of checked objects */
473	greg	1.1	FVECT curpos; /* current cube position */
474	greg	1.11	int sflags; /* sign flags */
475	greg	1.1	double t, dt;
476			register int i;
477
478	greg	1.21	nrays++; /* increment trace counter */
479	greg	1.11	sflags = 0;
480	greg	1.1	for (i = 0; i < 3; i++) {
481			curpos[i] = r->rorg[i];
482	greg	2.8	if (r->rdir[i] > 1e-7)
483	greg	1.11	sflags \|= 1 << i;
484	greg	2.8	else if (r->rdir[i] < -1e-7)
485	greg	1.11	sflags \|= 0x10 << i;
486	greg	1.1	}
487	greg	1.17	if (sflags == 0)
488			error(CONSISTENCY, "zero ray direction in localhit");
489	greg	2.17	/* start off assuming nothing hit */
490			if (r->rmax > FTINY) { /* except aft plane if one */
491			r->ro = &Aftplane;
492			r->rot = r->rmax;
493			for (i = 0; i < 3; i++)
494			r->rop[i] = r->rorg[i] + r->rot*r->rdir[i];
495			}
496			/* find global cube entrance point */
497	greg	1.1	t = 0.0;
498			if (!incube(scene, curpos)) {
499			/* find distance to entry */
500			for (i = 0; i < 3; i++) {
501			/* plane in our direction */
502	greg	1.11	if (sflags & 1<<i)
503	greg	1.1	dt = scene->cuorg[i];
504	greg	1.11	else if (sflags & 0x10<<i)
505	greg	1.1	dt = scene->cuorg[i] + scene->cusize;
506			else
507			continue;
508			/* distance to the plane */
509			dt = (dt - r->rorg[i])/r->rdir[i];
510			if (dt > t)
511			t = dt; /* farthest face is the one */
512			}
513			t += FTINY; /* fudge to get inside cube */
514	greg	2.17	if (t >= r->rot) /* clipped already */
515			return(0);
516	greg	1.1	/* advance position */
517			for (i = 0; i < 3; i++)
518			curpos[i] += r->rdir[i]*t;
519
520			if (!incube(scene, curpos)) /* non-intersecting ray */
521			return(0);
522			}
523	greg	2.3	cxset[0] = 0;
524	greg	2.19	raymove(curpos, cxset, sflags, r, scene);
525			return(r->ro != NULL & r->ro != &Aftplane);
526	greg	1.1	}
527
528
529			static int
530	greg	2.3	raymove(pos, cxs, dirf, r, cu) /* check for hit as we move */
531			FVECT pos; /* current position, modified herein */
532			OBJECT cxs; / checked objects, modified by checkhit */
533	greg	1.11	int dirf; /* direction indicators to speed tests */
534	greg	1.1	register RAY *r;
535			register CUBE *cu;
536			{
537			int ax;
538			double dt, t;
539
540			if (istree(cu->cutree)) { /* recurse on subcubes */
541			CUBE cukid;
542	greg	1.11	register int br, sgn;
543	greg	1.1
544			cukid.cusize = cu->cusize * 0.5; /* find subcube */
545			VCOPY(cukid.cuorg, cu->cuorg);
546			br = 0;
547			if (pos[0] >= cukid.cuorg[0]+cukid.cusize) {
548			cukid.cuorg[0] += cukid.cusize;
549			br \|= 1;
550			}
551			if (pos[1] >= cukid.cuorg[1]+cukid.cusize) {
552			cukid.cuorg[1] += cukid.cusize;
553			br \|= 2;
554			}
555			if (pos[2] >= cukid.cuorg[2]+cukid.cusize) {
556			cukid.cuorg[2] += cukid.cusize;
557			br \|= 4;
558			}
559			for ( ; ; ) {
560			cukid.cutree = octkid(cu->cutree, br);
561	greg	2.3	if ((ax = raymove(pos,cxs,dirf,r,&cukid)) == RAYHIT)
562	greg	1.1	return(RAYHIT);
563			sgn = 1 << ax;
564	greg	1.11	if (sgn & dirf) /* positive axis? */
565	greg	1.1	if (sgn & br)
566			return(ax); /* overflow */
567			else {
568			cukid.cuorg[ax] += cukid.cusize;
569			br \|= sgn;
570			}
571	greg	1.11	else
572			if (sgn & br) {
573			cukid.cuorg[ax] -= cukid.cusize;
574			br &= ~sgn;
575			} else
576			return(ax); /* underflow */
577	greg	1.1	}
578			/NOTREACHED/
579			}
580	greg	2.18	if (isfull(cu->cutree)) {
581			if (checkhit(r, cu, cxs))
582			return(RAYHIT);
583			} else if (r->ro == &Aftplane && incube(cu, r->rop))
584	greg	1.1	return(RAYHIT);
585			/* advance to next cube */
586	greg	1.11	if (dirf&0x11) {
587			dt = dirf&1 ? cu->cuorg[0] + cu->cusize : cu->cuorg[0];
588	greg	1.1	t = (dt - pos[0])/r->rdir[0];
589			ax = 0;
590			} else
591			t = FHUGE;
592	greg	1.11	if (dirf&0x22) {
593			dt = dirf&2 ? cu->cuorg[1] + cu->cusize : cu->cuorg[1];
594	greg	1.1	dt = (dt - pos[1])/r->rdir[1];
595			if (dt < t) {
596			t = dt;
597			ax = 1;
598			}
599			}
600	greg	1.11	if (dirf&0x44) {
601			dt = dirf&4 ? cu->cuorg[2] + cu->cusize : cu->cuorg[2];
602	greg	1.1	dt = (dt - pos[2])/r->rdir[2];
603			if (dt < t) {
604			t = dt;
605			ax = 2;
606			}
607			}
608			pos[0] += r->rdir[0]*t;
609			pos[1] += r->rdir[1]*t;
610			pos[2] += r->rdir[2]*t;
611			return(ax);
612			}
613
614
615	greg	2.34	static int
616	greg	2.3	checkhit(r, cu, cxs) /* check for hit in full cube */
617	greg	1.1	register RAY *r;
618			CUBE *cu;
619	greg	2.3	OBJECT *cxs;
620	greg	1.1	{
621			OBJECT oset[MAXSET+1];
622			register OBJREC *o;
623			register int i;
624
625			objset(oset, cu->cutree);
626	greg	2.3	checkset(oset, cxs); /* eliminate double-checking */
627	greg	1.1	for (i = oset[0]; i > 0; i--) {
628			o = objptr(oset[i]);
629	greg	2.28	if ((*ofun[o->otype].funp)(o, r))
630			r->robj = oset[i];
631	greg	1.1	}
632			if (r->ro == NULL)
633			return(0); /* no scores yet */
634
635			return(incube(cu, r->rop)); /* hit OK if in current cube */
636	greg	2.2	}
637
638
639	greg	2.34	static void
640	greg	2.2	checkset(os, cs) /* modify checked set and set to check */
641	greg	2.3	register OBJECT os; / os' = os - cs */
642			register OBJECT cs; / cs' = cs + os */
643	greg	2.2	{
644			OBJECT cset[MAXCSET+MAXSET+1];
645	greg	2.3	register int i, j;
646			int k;
647	greg	2.2	/* copy os in place, cset <- cs */
648			cset[0] = 0;
649			k = 0;
650			for (i = j = 1; i <= os[0]; i++) {
651			while (j <= cs[0] && cs[j] < os[i])
652			cset[++cset[0]] = cs[j++];
653			if (j > cs[0] \|\| os[i] != cs[j]) { /* object to check */
654			os[++k] = os[i];
655			cset[++cset[0]] = os[i];
656			}
657			}
658	greg	2.3	if (!(os[0] = k)) /* new "to check" set size */
659			return; /* special case */
660	greg	2.2	while (j <= cs[0]) /* get the rest of cs */
661			cset[++cset[0]] = cs[j++];
662	greg	2.3	if (cset[0] > MAXCSET) /* truncate "checked" set if nec. */
663	greg	2.2	cset[0] = MAXCSET;
664	greg	2.3	/* setcopy(cs, cset); / / copy cset back to cs */
665			os = cset;
666			for (i = os[0]; i-- >= 0; )
667			cs++ = os++;
668	greg	1.1	}