src/rt/raytrace.c

#ifndef lint
static const char RCSid[] = "$Id: raytrace.c,v 2.75 2019/02/13 01:00:31 greg Exp $";
#endif
/*
 *  raytrace.c - routines for tracing and shading rays.
 *
 *  External symbols declared in ray.h
 */

#include "copyright.h"

#include  "ray.h"
#include  "source.h"
#include  "otypes.h"
#include  "otspecial.h"
#include  "random.h"
#include  "pmap.h"

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

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

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

OBJREC  Aftplane;                       /* aft clipping plane object */

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

static int raymove(FVECT  pos, OBJECT  *cxs, int  dirf, RAY  *r, CUBE  *cu);
static int checkhit(RAY  *r, CUBE  *cu, OBJECT  *cxs);
static void checkset(OBJECT  *os, OBJECT  *cs);


int
rayorigin(              /* start new ray from old one */
        RAY  *r,
        int  rt,
        const RAY  *ro,
        const COLOR rc
)
{
        double  rw, re;
                                                /* assign coefficient/weight */
        if (rc == NULL) {
                rw = 1.0;
                setcolor(r->rcoef, 1., 1., 1.);
        } else {
                rw = intens(rc);
                if (rw > 1.0)
                        rw = 1.0;               /* avoid calculation growth */
                if (rc != r->rcoef)
                        copycolor(r->rcoef, rc);
        }
        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 */
                if (ro->rot >= FHUGE) {
                        memset(r, 0, sizeof(RAY));
                        return(-1);             /* illegal continuation */
                }
                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 extinction */
                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);
                re *= ro->rot;
                if (re > 0.1) {
                        if (re > 92.) {
                                r->rweight = 0.0;
                        } else {
                                r->rweight *= exp(-re);
                        }
                }
        }
        rayclear(r);
        if (r->rweight <= 0.0)                  /* check for expiration */
                return(-1);
        if (r->crtype & SHADOW)                 /* shadow commitment */
                return(0);
                                                /* ambient in photon map? */
        if (ro != NULL && ro->crtype & AMBIENT) {
                if (causticPhotonMapping)
                        return(-1);
                if (photonMapping && rt != TRANS)
                        return(-1);
        }
        if (maxdepth <= 0 && rc != NULL) {      /* Russian roulette */
                if (minweight <= 0.0)
                        error(USER, "zero ray weight in Russian roulette");
                if (maxdepth < 0 && r->rlvl > -maxdepth)
                        return(-1);             /* upper reflection limit */
                if (r->rweight >= minweight)
                        return(0);
                if (frandom() > r->rweight/minweight)
                        return(-1);
                rw = minweight/r->rweight;      /* promote survivor */
                scalecolor(r->rcoef, rw);
                r->rweight = minweight;
                return(0);
        }
        return(r->rweight >= minweight && r->rlvl <= abs(maxdepth) ? 0 : -1);
}


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


void
raytrace(                       /* 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 */

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

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


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


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

        rayorigin(&tr, TRANS, r, NULL);         /* always continue */
        VCOPY(tr.rdir, r->rdir);
        rayvalue(&tr);
        copycolor(r->mcol, tr.mcol);
        copycolor(r->rcol, tr.rcol);
        r->rmt = r->rot + tr.rmt;
        r->rxt = r->rot + tr.rxt;
}


int
raytirrad(                      /* irradiance hack */
        OBJREC  *m,
        RAY     *r
)
{
        if (ofun[m->otype].flags & (T_M|T_X) && m->otype != MAT_CLIP) {
                if (istransp(m->otype) || isBSDFproxy(m)) {
                        raytrans(r);
                        return(1);
                }
                if (!islight(m->otype))
                        return((*ofun[Lamb.otype].funp)(&Lamb, r));
        }
        return(0);              /* not a qualifying surface */
}


int
rayshade(               /* shade ray r with material mod */
        RAY  *r,
        int  mod
)
{
        int     tst_irrad = do_irrad && !(r->crtype & ~(PRIMARY|TRANS));
        OBJREC  *m;

        r->rxt = r->rmt = r->rot;       /* preset effective ray length */
        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);
                }
                ******/
                                        /* hack for irradiance calculation */
                if (tst_irrad && raytirrad(m, r))
                        return(1);

                if ((*ofun[m->otype].funp)(m, r))
                        return(1);      /* materials call raytexture() */
        }
        return(0);                      /* no material! */
}


void
rayparticipate(                 /* compute ray medium participation */
        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<=FTINY ? 1. : re>92. ? 0. : exp(-re),
                        ge<=FTINY ? 1. : ge>92. ? 0. : exp(-ge),
                        be<=FTINY ? 1. : be>92. ? 0. : exp(-be));
        multcolor(r->rcol, ce);                 /* path extinction */
        if (r->crtype & SHADOW || intens(r->albedo) <= FTINY)
                return;                         /* no scattering */
        
        /* PMAP: indirect inscattering accounted for by volume photons? */
        if (!volumePhotonMapping) {
                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 */
}


void
raytexture(                     /* get material modifiers */
        RAY  *r,
        OBJECT  mod
)
{
        OBJREC  *m;
                                        /* 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);
                }
        }
}


int
raymixture(             /* mix modifiers */
        RAY  *r,
        OBJECT  fore,
        OBJECT  back,
        double  coef
)
{
        RAY  fr, br;
        double  mfore, mback;
        int  foremat, backmat;
        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 */
        fr = *r;
        if (coef > FTINY) {
                fr.rweight *= coef;
                scalecolor(fr.rcoef, coef);
                foremat = rayshade(&fr, fore);
        }
                                        /* background */
        br = *r;
        if (coef < 1.0-FTINY) {
                br.rweight *= 1.0-coef;
                scalecolor(br.rcoef, 1.0-coef);
                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);
        scalecolor(fr.mcol, coef);
        scalecolor(br.mcol, 1.0-coef);
        copycolor(r->mcol, fr.mcol);
        addcolor(r->mcol, br.mcol);
        mfore = bright(fr.mcol); mback = bright(br.mcol);
        r->rmt = mfore > mback ? fr.rmt : br.rmt;
        r->rxt = bright(fr.rcol)-mfore > bright(br.rcol)-mback ?
                        fr.rxt : br.rxt;
        return(1);
}


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

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


void
raycontrib(             /* compute (cumulative) ray contribution */
        RREAL  rc[3],
        const RAY  *r,
        int  flags
)
{
        rc[0] = rc[1] = rc[2] = 1.;

        while (r != NULL && r->crtype&flags) {
                int     i = 3;
                while (i--)
                        rc[i] *= colval(r->rcoef,i);
                r = r->parent;
        }
}


double
raynormal(              /* compute perturbed normal for ray */
        FVECT  norm,
        RAY  *r
)
{
        double  newdot;
        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(                       /* get new tranformation matrix for ray */
        RAY  *r
)
{
        static struct xfn {
                struct xfn  *next;
                FULLXF  xf;
        }  xfseed = { &xfseed }, *xflast = &xfseed;
        struct xfn  *xp;
        const 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 *)bmalloc(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(                    /* reverse surface orientation */
        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];
}


void
rayhit(                 /* standard ray hit test */
        OBJECT  *oset,
        RAY  *r
)
{
        OBJREC  *o;
        int     i;

        for (i = oset[0]; i > 0; i--) {
                o = objptr(oset[i]);
                if ((*ofun[o->otype].funp)(o, r))
                        r->robj = oset[i];
        }
}


int
localhit(               /* check for hit in the octree */
        RAY  *r,
        CUBE  *scene
)
{
        OBJECT  cxset[MAXCSET+1];       /* set of checked objects */
        FVECT  curpos;                  /* current cube position */
        int  sflags;                    /* sign flags */
        double  t, dt;
        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) {
                error(WARNING, "zero ray direction in localhit");
                return(0);
        }
                                        /* start off assuming nothing hit */
        if (r->rmax > FTINY) {          /* except aft plane if one */
                r->ro = &Aftplane;
                r->rot = r->rmax;
                VSUM(r->rop, r->rorg, r->rdir, r->rot);
        }
                                        /* 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 */
                VSUM(curpos, curpos, r->rdir, 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(                /* 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 */
        RAY  *r,
        CUBE  *cu
)
{
        int  ax;
        double  dt, t;

        if (istree(cu->cutree)) {               /* recurse on subcubes */
                CUBE  cukid;
                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;
                }
        }
        VSUM(pos, pos, r->rdir, t);
        return(ax);
}


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

        objset(oset, cu->cutree);
        checkset(oset, cxs);                    /* avoid double-checking */

        (*r->hitf)(oset, r);                    /* test for hit in set */

        if (r->robj == OVOID)
                return(0);                      /* no scores yet */

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


static void
checkset(               /* modify checked set and set to check */
        OBJECT  *os,                    /* os' = os - cs */
        OBJECT  *cs                     /* cs' = cs + os */
)
{
        OBJECT  cset[MAXCSET+MAXSET+1];
        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:	2.76
Committed:	Fri Feb 22 17:12:58 2019 UTC (5 years, 2 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.75:	+3 -11 lines
Log Message:	Removed ray contribution hack for participating media b/c it doesn't really work
#	User	Rev	Content
1	greg	1.1	#ifndef lint
2	greg	2.76	static const char RCSid[] = "$Id: raytrace.c,v 2.75 2019/02/13 01:00:31 greg Exp $";
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	greg	2.35	#include "copyright.h"
11	greg	1.1
12			#include "ray.h"
13	schorsch	2.45	#include "source.h"
14	greg	1.1	#include "otypes.h"
15	greg	1.15	#include "otspecial.h"
16	greg	2.51	#include "random.h"
17	greg	2.66	#include "pmap.h"
18	greg	1.15
19	greg	2.3	#define MAXCSET ((MAXSET+1)2-1) / maximum check set size */
20
21	greg	2.60	RNUMBER raynum = 0; /* next unique ray number */
22			RNUMBER nrays = 0; /* number of calls to localhit */
23	greg	1.1
24	schorsch	2.40	static RREAL Lambfa[5] = {PI, PI, PI, 0.0, 0.0};
25	greg	1.15	OBJREC Lamb = {
26			OVOID, MAT_PLASTIC, "Lambertian",
27	greg	2.57	{NULL, Lambfa, 0, 5}, NULL
28	greg	1.15	}; /* a Lambertian surface */
29
30	greg	2.17	OBJREC Aftplane; /* aft clipping plane object */
31	greg	2.16
32	schorsch	2.45	#define RAYHIT (-1) /* return value for intercepted ray */
33	greg	2.5
34	schorsch	2.45	static int raymove(FVECT pos, OBJECT cxs, int dirf, RAY r, CUBE *cu);
35			static int checkhit(RAY r, CUBE cu, OBJECT *cxs);
36			static void checkset(OBJECT os, OBJECT cs);
37	greg	1.1
38
39	greg	2.65	int
40	schorsch	2.45	rayorigin( /* start new ray from old one */
41	greg	2.49	RAY *r,
42	schorsch	2.45	int rt,
43	greg	2.49	const RAY *ro,
44			const COLOR rc
45	schorsch	2.45	)
46	greg	1.1	{
47	greg	2.49	double rw, re;
48			/* assign coefficient/weight */
49			if (rc == NULL) {
50			rw = 1.0;
51			setcolor(r->rcoef, 1., 1., 1.);
52			} else {
53			rw = intens(rc);
54	greg	2.70	if (rw > 1.0)
55			rw = 1.0; /* avoid calculation growth */
56	greg	2.49	if (rc != r->rcoef)
57			copycolor(r->rcoef, rc);
58			}
59	greg	1.1	if ((r->parent = ro) == NULL) { /* primary ray */
60			r->rlvl = 0;
61			r->rweight = rw;
62			r->crtype = r->rtype = rt;
63			r->rsrc = -1;
64			r->clipset = NULL;
65	greg	2.50	r->revf = raytrace;
66	greg	2.23	copycolor(r->cext, cextinction);
67	greg	2.26	copycolor(r->albedo, salbedo);
68	greg	2.23	r->gecc = seccg;
69			r->slights = NULL;
70	greg	1.1	} else { /* spawned ray */
71	greg	2.49	if (ro->rot >= FHUGE) {
72			memset(r, 0, sizeof(RAY));
73			return(-1); /* illegal continuation */
74			}
75	greg	1.1	r->rlvl = ro->rlvl;
76			if (rt & RAYREFL) {
77			r->rlvl++;
78			r->rsrc = -1;
79			r->clipset = ro->clipset;
80	greg	2.22	r->rmax = 0.0;
81	greg	1.1	} else {
82			r->rsrc = ro->rsrc;
83			r->clipset = ro->newcset;
84	greg	2.22	r->rmax = ro->rmax <= FTINY ? 0.0 : ro->rmax - ro->rot;
85	greg	1.1	}
86	greg	2.50	r->revf = ro->revf;
87	greg	2.23	copycolor(r->cext, ro->cext);
88	greg	2.26	copycolor(r->albedo, ro->albedo);
89	greg	2.23	r->gecc = ro->gecc;
90			r->slights = ro->slights;
91	greg	1.1	r->crtype = ro->crtype \| (r->rtype = rt);
92			VCOPY(r->rorg, ro->rop);
93	gwlarson	2.31	r->rweight = ro->rweight * rw;
94	greg	2.49	/* estimate extinction */
95	gwlarson	2.31	re = colval(ro->cext,RED) < colval(ro->cext,GRN) ?
96			colval(ro->cext,RED) : colval(ro->cext,GRN);
97			if (colval(ro->cext,BLU) < re) re = colval(ro->cext,BLU);
98	greg	2.49	re *= ro->rot;
99	schorsch	2.58	if (re > 0.1) {
100			if (re > 92.) {
101	greg	2.53	r->rweight = 0.0;
102	schorsch	2.58	} else {
103	greg	2.53	r->rweight *= exp(-re);
104	schorsch	2.58	}
105			}
106	greg	1.1	}
107	greg	1.22	rayclear(r);
108	greg	2.53	if (r->rweight <= 0.0) /* check for expiration */
109			return(-1);
110	greg	2.52	if (r->crtype & SHADOW) /* shadow commitment */
111			return(0);
112	greg	2.67	/* ambient in photon map? */
113	greg	2.69	if (ro != NULL && ro->crtype & AMBIENT) {
114			if (causticPhotonMapping)
115			return(-1);
116			if (photonMapping && rt != TRANS)
117			return(-1);
118			}
119	greg	2.51	if (maxdepth <= 0 && rc != NULL) { /* Russian roulette */
120			if (minweight <= 0.0)
121			error(USER, "zero ray weight in Russian roulette");
122			if (maxdepth < 0 && r->rlvl > -maxdepth)
123			return(-1); /* upper reflection limit */
124			if (r->rweight >= minweight)
125			return(0);
126	greg	2.55	if (frandom() > r->rweight/minweight)
127	greg	2.51	return(-1);
128			rw = minweight/r->rweight; /* promote survivor */
129			scalecolor(r->rcoef, rw);
130			r->rweight = minweight;
131			return(0);
132			}
133	greg	2.64	return(r->rweight >= minweight && r->rlvl <= abs(maxdepth) ? 0 : -1);
134	greg	1.22	}
135
136
137	greg	2.65	void
138	schorsch	2.45	rayclear( /* clear a ray for (re)evaluation */
139	greg	2.64	RAY *r
140	schorsch	2.45	)
141	greg	1.22	{
142	greg	1.20	r->rno = raynum++;
143	greg	1.1	r->newcset = r->clipset;
144	greg	2.36	r->hitf = rayhit;
145	greg	2.28	r->robj = OVOID;
146	greg	2.17	r->ro = NULL;
147	greg	2.34	r->rox = NULL;
148	greg	2.73	r->rxt = r->rmt = r->rot = FHUGE;
149	greg	1.1	r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
150	greg	2.37	r->uv[0] = r->uv[1] = 0.0;
151	greg	1.1	setcolor(r->pcol, 1.0, 1.0, 1.0);
152	greg	2.73	setcolor(r->mcol, 0.0, 0.0, 0.0);
153	greg	1.1	setcolor(r->rcol, 0.0, 0.0, 0.0);
154			}
155
156
157	greg	2.65	void
158	greg	2.50	raytrace( /* trace a ray and compute its value */
159	schorsch	2.45	RAY *r
160			)
161	greg	1.1	{
162	greg	1.15	if (localhit(r, &thescene))
163	greg	2.24	raycont(r); /* hit local surface, evaluate */
164	greg	2.16	else if (r->ro == &Aftplane) {
165	greg	2.23	r->ro = NULL; /* hit aft clipping plane */
166	greg	2.16	r->rot = FHUGE;
167			} else if (sourcehit(r))
168	greg	2.24	rayshade(r, r->ro->omod); /* distant source */
169	greg	1.1
170			if (trace != NULL)
171			(trace)(r); / trace execution */
172	greg	2.49
173			rayparticipate(r); /* for participating medium */
174	greg	1.1	}
175
176
177	greg	2.65	void
178	schorsch	2.45	raycont( /* check for clipped object and continue */
179	greg	2.64	RAY *r
180	schorsch	2.45	)
181	greg	1.8	{
182	greg	2.7	if ((r->clipset != NULL && inset(r->clipset, r->ro->omod)) \|\|
183	greg	2.24	!rayshade(r, r->ro->omod))
184	greg	1.8	raytrans(r);
185			}
186
187
188	greg	2.65	void
189	schorsch	2.45	raytrans( /* transmit ray as is */
190	greg	2.64	RAY *r
191	schorsch	2.45	)
192	greg	1.1	{
193			RAY tr;
194
195	greg	2.67	rayorigin(&tr, TRANS, r, NULL); /* always continue */
196			VCOPY(tr.rdir, r->rdir);
197			rayvalue(&tr);
198	greg	2.75	copycolor(r->mcol, tr.mcol);
199	greg	2.67	copycolor(r->rcol, tr.rcol);
200	greg	2.73	r->rmt = r->rot + tr.rmt;
201			r->rxt = r->rot + tr.rxt;
202	greg	1.1	}
203
204
205	greg	2.65	int
206	greg	2.74	raytirrad( /* irradiance hack */
207			OBJREC *m,
208			RAY *r
209			)
210			{
211	greg	2.75	if (ofun[m->otype].flags & (T_M\|T_X) && m->otype != MAT_CLIP) {
212	greg	2.74	if (istransp(m->otype) \|\| isBSDFproxy(m)) {
213			raytrans(r);
214			return(1);
215			}
216			if (!islight(m->otype))
217			return((*ofun[Lamb.otype].funp)(&Lamb, r));
218			}
219			return(0); /* not a qualifying surface */
220			}
221
222
223			int
224	schorsch	2.45	rayshade( /* shade ray r with material mod */
225	greg	2.64	RAY *r,
226	schorsch	2.45	int mod
227			)
228	greg	1.1	{
229	greg	2.74	int tst_irrad = do_irrad && !(r->crtype & ~(PRIMARY\|TRANS));
230	greg	2.64	OBJREC *m;
231	greg	2.47
232	greg	2.73	r->rxt = r->rmt = r->rot; /* preset effective ray length */
233	greg	2.47	for ( ; mod != OVOID; mod = m->omod) {
234	greg	1.1	m = objptr(mod);
235	greg	1.4	/****** unnecessary test since modifier() is always called
236	greg	1.1	if (!ismodifier(m->otype)) {
237			sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
238			error(USER, errmsg);
239			}
240	greg	1.4	******/
241	greg	1.16	/* hack for irradiance calculation */
242	greg	2.74	if (tst_irrad && raytirrad(m, r))
243			return(1);
244
245	greg	2.47	if ((*ofun[m->otype].funp)(m, r))
246			return(1); /* materials call raytexture() */
247	greg	1.1	}
248	greg	2.47	return(0); /* no material! */
249	greg	2.23	}
250
251
252	greg	2.65	void
253	schorsch	2.45	rayparticipate( /* compute ray medium participation */
254	greg	2.64	RAY *r
255	schorsch	2.45	)
256	greg	2.23	{
257			COLOR ce, ca;
258			double re, ge, be;
259
260			if (intens(r->cext) <= 1./FHUGE)
261			return; /* no medium */
262	greg	2.27	re = r->rot*colval(r->cext,RED);
263			ge = r->rot*colval(r->cext,GRN);
264			be = r->rot*colval(r->cext,BLU);
265	greg	2.26	if (r->crtype & SHADOW) { /* no scattering for sources */
266			re *= 1. - colval(r->albedo,RED);
267			ge *= 1. - colval(r->albedo,GRN);
268			be *= 1. - colval(r->albedo,BLU);
269			}
270	greg	2.49	setcolor(ce, re<=FTINY ? 1. : re>92. ? 0. : exp(-re),
271			ge<=FTINY ? 1. : ge>92. ? 0. : exp(-ge),
272			be<=FTINY ? 1. : be>92. ? 0. : exp(-be));
273			multcolor(r->rcol, ce); /* path extinction */
274	greg	2.26	if (r->crtype & SHADOW \|\| intens(r->albedo) <= FTINY)
275	greg	2.23	return; /* no scattering */
276	greg	2.66
277			/* PMAP: indirect inscattering accounted for by volume photons? */
278			if (!volumePhotonMapping) {
279			setcolor(ca,
280			colval(r->albedo,RED)colval(ambval,RED)(1.-colval(ce,RED)),
281			colval(r->albedo,GRN)colval(ambval,GRN)(1.-colval(ce,GRN)),
282			colval(r->albedo,BLU)colval(ambval,BLU)(1.-colval(ce,BLU)));
283			addcolor(r->rcol, ca); /* ambient in scattering */
284			}
285
286	greg	2.23	srcscatter(r); /* source in scattering */
287	greg	1.1	}
288
289
290	greg	2.65	void
291	schorsch	2.45	raytexture( /* get material modifiers */
292			RAY *r,
293			OBJECT mod
294			)
295	greg	1.1	{
296	greg	2.64	OBJREC *m;
297	greg	1.1	/* execute textures and patterns */
298			for ( ; mod != OVOID; mod = m->omod) {
299			m = objptr(mod);
300	greg	2.9	/****** unnecessary test since modifier() is always called
301			if (!ismodifier(m->otype)) {
302	greg	1.1	sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
303			error(USER, errmsg);
304			}
305	greg	2.9	******/
306	greg	2.20	if ((*ofun[m->otype].funp)(m, r)) {
307			sprintf(errmsg, "conflicting material \"%s\"",
308			m->oname);
309			objerror(r->ro, USER, errmsg);
310			}
311	greg	1.1	}
312			}
313
314
315	greg	2.65	int
316	schorsch	2.45	raymixture( /* mix modifiers */
317	greg	2.64	RAY *r,
318	schorsch	2.45	OBJECT fore,
319			OBJECT back,
320			double coef
321			)
322	greg	1.1	{
323	greg	2.9	RAY fr, br;
324	greg	2.73	double mfore, mback;
325	greg	2.9	int foremat, backmat;
326	greg	2.64	int i;
327	greg	2.24	/* bound coefficient */
328	greg	1.1	if (coef > 1.0)
329			coef = 1.0;
330			else if (coef < 0.0)
331			coef = 0.0;
332	greg	2.13	/* compute foreground and background */
333	greg	2.24	foremat = backmat = 0;
334	greg	2.9	/* foreground */
335	schorsch	2.41	fr = *r;
336	greg	2.54	if (coef > FTINY) {
337	greg	2.59	fr.rweight *= coef;
338	greg	2.54	scalecolor(fr.rcoef, coef);
339	greg	2.9	foremat = rayshade(&fr, fore);
340	greg	2.54	}
341	greg	2.9	/* background */
342	schorsch	2.41	br = *r;
343	greg	2.54	if (coef < 1.0-FTINY) {
344	greg	2.59	br.rweight *= 1.0-coef;
345	greg	2.54	scalecolor(br.rcoef, 1.0-coef);
346	greg	2.9	backmat = rayshade(&br, back);
347	greg	2.54	}
348	greg	2.24	/* check for transparency */
349	schorsch	2.41	if (backmat ^ foremat) {
350	gwlarson	2.33	if (backmat && coef > FTINY)
351	greg	2.24	raytrans(&fr);
352	gwlarson	2.33	else if (foremat && coef < 1.0-FTINY)
353	greg	2.24	raytrans(&br);
354	schorsch	2.41	}
355	greg	2.12	/* mix perturbations */
356	greg	1.1	for (i = 0; i < 3; i++)
357	greg	2.12	r->pert[i] = coeffr.pert[i] + (1.0-coef)br.pert[i];
358			/* mix pattern colors */
359	greg	2.9	scalecolor(fr.pcol, coef);
360			scalecolor(br.pcol, 1.0-coef);
361	greg	2.12	copycolor(r->pcol, fr.pcol);
362			addcolor(r->pcol, br.pcol);
363	greg	2.24	/* return value tells if material */
364			if (!foremat & !backmat)
365			return(0);
366	greg	2.12	/* mix returned ray values */
367	greg	2.24	scalecolor(fr.rcol, coef);
368			scalecolor(br.rcol, 1.0-coef);
369			copycolor(r->rcol, fr.rcol);
370			addcolor(r->rcol, br.rcol);
371	greg	2.75	scalecolor(fr.mcol, coef);
372			scalecolor(br.mcol, 1.0-coef);
373			copycolor(r->mcol, fr.mcol);
374			addcolor(r->mcol, br.mcol);
375	greg	2.73	mfore = bright(fr.mcol); mback = bright(br.mcol);
376			r->rmt = mfore > mback ? fr.rmt : br.rmt;
377			r->rxt = bright(fr.rcol)-mfore > bright(br.rcol)-mback ?
378			fr.rxt : br.rxt;
379	greg	2.24	return(1);
380	greg	1.1	}
381
382
383	greg	2.65	double
384	schorsch	2.45	raydist( /* compute (cumulative) ray distance */
385	greg	2.64	const RAY *r,
386			int flags
387	schorsch	2.45	)
388	greg	2.21	{
389			double sum = 0.0;
390
391			while (r != NULL && r->crtype&flags) {
392			sum += r->rot;
393			r = r->parent;
394			}
395			return(sum);
396			}
397
398
399	greg	2.65	void
400	greg	2.49	raycontrib( /* compute (cumulative) ray contribution */
401	greg	2.63	RREAL rc[3],
402	greg	2.49	const RAY *r,
403			int flags
404			)
405			{
406	greg	2.52	rc[0] = rc[1] = rc[2] = 1.;
407	greg	2.49
408			while (r != NULL && r->crtype&flags) {
409	greg	2.76	int i = 3;
410			while (i--)
411	greg	2.52	rc[i] *= colval(r->rcoef,i);
412	greg	2.49	r = r->parent;
413			}
414			}
415
416
417	greg	2.65	double
418	schorsch	2.45	raynormal( /* compute perturbed normal for ray */
419			FVECT norm,
420	greg	2.64	RAY *r
421	schorsch	2.45	)
422	greg	1.1	{
423			double newdot;
424	greg	2.64	int i;
425	greg	1.1
426			/* The perturbation is added to the surface normal to obtain
427			* the new normal. If the new normal would affect the surface
428			* orientation wrt. the ray, a correction is made. The method is
429			* still fraught with problems since reflected rays and similar
430			* directions calculated from the surface normal may spawn rays behind
431			* the surface. The only solution is to curb textures at high
432	greg	1.9	* incidence (namely, keep DOT(rdir,pert) < Rdot).
433	greg	1.1	*/
434
435			for (i = 0; i < 3; i++)
436			norm[i] = r->ron[i] + r->pert[i];
437
438			if (normalize(norm) == 0.0) {
439			objerror(r->ro, WARNING, "illegal normal perturbation");
440			VCOPY(norm, r->ron);
441			return(r->rod);
442			}
443			newdot = -DOT(norm, r->rdir);
444			if ((newdot > 0.0) != (r->rod > 0.0)) { /* fix orientation */
445			for (i = 0; i < 3; i++)
446			norm[i] += 2.0newdotr->rdir[i];
447			newdot = -newdot;
448			}
449			return(newdot);
450	greg	1.12	}
451
452
453	greg	2.65	void
454	schorsch	2.45	newrayxf( /* get new tranformation matrix for ray */
455			RAY *r
456			)
457	greg	1.12	{
458			static struct xfn {
459			struct xfn *next;
460			FULLXF xf;
461			} xfseed = { &xfseed }, *xflast = &xfseed;
462	greg	2.64	struct xfn *xp;
463			const RAY *rp;
464	greg	1.12
465			/*
466			* Search for transform in circular list that
467			* has no associated ray in the tree.
468			*/
469			xp = xflast;
470			for (rp = r->parent; rp != NULL; rp = rp->parent)
471			if (rp->rox == &xp->xf) { /* xp in use */
472			xp = xp->next; /* move to next */
473			if (xp == xflast) { /* need new one */
474	greg	2.64	xp = (struct xfn *)bmalloc(sizeof(struct xfn));
475	greg	1.12	if (xp == NULL)
476			error(SYSTEM,
477			"out of memory in newrayxf");
478			/* insert in list */
479			xp->next = xflast->next;
480			xflast->next = xp;
481			break; /* we're done */
482			}
483			rp = r; /* start check over */
484			}
485			/* got it */
486			r->rox = &xp->xf;
487			xflast = xp;
488	greg	1.1	}
489
490
491	greg	2.65	void
492	schorsch	2.45	flipsurface( /* reverse surface orientation */
493	greg	2.64	RAY *r
494	schorsch	2.45	)
495	greg	1.1	{
496			r->rod = -r->rod;
497			r->ron[0] = -r->ron[0];
498			r->ron[1] = -r->ron[1];
499			r->ron[2] = -r->ron[2];
500			r->pert[0] = -r->pert[0];
501			r->pert[1] = -r->pert[1];
502			r->pert[2] = -r->pert[2];
503			}
504
505
506	greg	2.65	void
507	schorsch	2.45	rayhit( /* standard ray hit test */
508			OBJECT *oset,
509			RAY *r
510			)
511	greg	2.36	{
512			OBJREC *o;
513			int i;
514
515			for (i = oset[0]; i > 0; i--) {
516			o = objptr(oset[i]);
517			if ((*ofun[o->otype].funp)(o, r))
518			r->robj = oset[i];
519			}
520			}
521
522
523	greg	2.65	int
524	schorsch	2.45	localhit( /* check for hit in the octree */
525	greg	2.64	RAY *r,
526			CUBE *scene
527	schorsch	2.45	)
528	greg	1.1	{
529	greg	2.3	OBJECT cxset[MAXCSET+1]; /* set of checked objects */
530	greg	1.1	FVECT curpos; /* current cube position */
531	greg	1.11	int sflags; /* sign flags */
532	greg	1.1	double t, dt;
533	greg	2.64	int i;
534	greg	1.1
535	greg	1.21	nrays++; /* increment trace counter */
536	greg	1.11	sflags = 0;
537	greg	1.1	for (i = 0; i < 3; i++) {
538			curpos[i] = r->rorg[i];
539	greg	2.8	if (r->rdir[i] > 1e-7)
540	greg	1.11	sflags \|= 1 << i;
541	greg	2.8	else if (r->rdir[i] < -1e-7)
542	greg	1.11	sflags \|= 0x10 << i;
543	greg	1.1	}
544	greg	2.61	if (!sflags) {
545			error(WARNING, "zero ray direction in localhit");
546			return(0);
547			}
548	greg	2.17	/* start off assuming nothing hit */
549			if (r->rmax > FTINY) { /* except aft plane if one */
550			r->ro = &Aftplane;
551			r->rot = r->rmax;
552	greg	2.62	VSUM(r->rop, r->rorg, r->rdir, r->rot);
553	greg	2.17	}
554			/* find global cube entrance point */
555	greg	1.1	t = 0.0;
556			if (!incube(scene, curpos)) {
557			/* find distance to entry */
558			for (i = 0; i < 3; i++) {
559			/* plane in our direction */
560	greg	1.11	if (sflags & 1<<i)
561	greg	1.1	dt = scene->cuorg[i];
562	greg	1.11	else if (sflags & 0x10<<i)
563	greg	1.1	dt = scene->cuorg[i] + scene->cusize;
564			else
565			continue;
566			/* distance to the plane */
567			dt = (dt - r->rorg[i])/r->rdir[i];
568			if (dt > t)
569			t = dt; /* farthest face is the one */
570			}
571			t += FTINY; /* fudge to get inside cube */
572	greg	2.17	if (t >= r->rot) /* clipped already */
573			return(0);
574	greg	1.1	/* advance position */
575	greg	2.62	VSUM(curpos, curpos, r->rdir, t);
576	greg	1.1
577			if (!incube(scene, curpos)) /* non-intersecting ray */
578			return(0);
579			}
580	greg	2.3	cxset[0] = 0;
581	greg	2.19	raymove(curpos, cxset, sflags, r, scene);
582	schorsch	2.42	return((r->ro != NULL) & (r->ro != &Aftplane));
583	greg	1.1	}
584
585
586			static int
587	schorsch	2.45	raymove( /* check for hit as we move */
588			FVECT pos, /* current position, modified herein */
589			OBJECT cxs, / checked objects, modified by checkhit */
590			int dirf, /* direction indicators to speed tests */
591	greg	2.64	RAY *r,
592			CUBE *cu
593	schorsch	2.45	)
594	greg	1.1	{
595			int ax;
596			double dt, t;
597
598			if (istree(cu->cutree)) { /* recurse on subcubes */
599			CUBE cukid;
600	greg	2.64	int br, sgn;
601	greg	1.1
602			cukid.cusize = cu->cusize * 0.5; /* find subcube */
603			VCOPY(cukid.cuorg, cu->cuorg);
604			br = 0;
605			if (pos[0] >= cukid.cuorg[0]+cukid.cusize) {
606			cukid.cuorg[0] += cukid.cusize;
607			br \|= 1;
608			}
609			if (pos[1] >= cukid.cuorg[1]+cukid.cusize) {
610			cukid.cuorg[1] += cukid.cusize;
611			br \|= 2;
612			}
613			if (pos[2] >= cukid.cuorg[2]+cukid.cusize) {
614			cukid.cuorg[2] += cukid.cusize;
615			br \|= 4;
616			}
617			for ( ; ; ) {
618			cukid.cutree = octkid(cu->cutree, br);
619	greg	2.3	if ((ax = raymove(pos,cxs,dirf,r,&cukid)) == RAYHIT)
620	greg	1.1	return(RAYHIT);
621			sgn = 1 << ax;
622	greg	1.11	if (sgn & dirf) /* positive axis? */
623	greg	1.1	if (sgn & br)
624			return(ax); /* overflow */
625			else {
626			cukid.cuorg[ax] += cukid.cusize;
627			br \|= sgn;
628			}
629	greg	1.11	else
630			if (sgn & br) {
631			cukid.cuorg[ax] -= cukid.cusize;
632			br &= ~sgn;
633			} else
634			return(ax); /* underflow */
635	greg	1.1	}
636			/NOTREACHED/
637			}
638	greg	2.18	if (isfull(cu->cutree)) {
639			if (checkhit(r, cu, cxs))
640			return(RAYHIT);
641			} else if (r->ro == &Aftplane && incube(cu, r->rop))
642	greg	1.1	return(RAYHIT);
643			/* advance to next cube */
644	greg	1.11	if (dirf&0x11) {
645			dt = dirf&1 ? cu->cuorg[0] + cu->cusize : cu->cuorg[0];
646	greg	1.1	t = (dt - pos[0])/r->rdir[0];
647			ax = 0;
648			} else
649			t = FHUGE;
650	greg	1.11	if (dirf&0x22) {
651			dt = dirf&2 ? cu->cuorg[1] + cu->cusize : cu->cuorg[1];
652	greg	1.1	dt = (dt - pos[1])/r->rdir[1];
653			if (dt < t) {
654			t = dt;
655			ax = 1;
656			}
657			}
658	greg	1.11	if (dirf&0x44) {
659			dt = dirf&4 ? cu->cuorg[2] + cu->cusize : cu->cuorg[2];
660	greg	1.1	dt = (dt - pos[2])/r->rdir[2];
661			if (dt < t) {
662			t = dt;
663			ax = 2;
664			}
665			}
666	greg	2.62	VSUM(pos, pos, r->rdir, t);
667	greg	1.1	return(ax);
668			}
669
670
671	greg	2.34	static int
672	schorsch	2.45	checkhit( /* check for hit in full cube */
673	greg	2.64	RAY *r,
674	schorsch	2.45	CUBE *cu,
675			OBJECT *cxs
676			)
677	greg	1.1	{
678			OBJECT oset[MAXSET+1];
679
680			objset(oset, cu->cutree);
681	greg	2.36	checkset(oset, cxs); /* avoid double-checking */
682
683			(r->hitf)(oset, r); / test for hit in set */
684
685			if (r->robj == OVOID)
686	greg	1.1	return(0); /* no scores yet */
687
688			return(incube(cu, r->rop)); /* hit OK if in current cube */
689	greg	2.2	}
690
691
692	greg	2.34	static void
693	schorsch	2.45	checkset( /* modify checked set and set to check */
694	greg	2.64	OBJECT os, / os' = os - cs */
695			OBJECT cs / cs' = cs + os */
696	schorsch	2.45	)
697	greg	2.2	{
698			OBJECT cset[MAXCSET+MAXSET+1];
699	greg	2.64	int i, j;
700	greg	2.3	int k;
701	greg	2.2	/* copy os in place, cset <- cs */
702			cset[0] = 0;
703			k = 0;
704			for (i = j = 1; i <= os[0]; i++) {
705			while (j <= cs[0] && cs[j] < os[i])
706			cset[++cset[0]] = cs[j++];
707			if (j > cs[0] \|\| os[i] != cs[j]) { /* object to check */
708			os[++k] = os[i];
709			cset[++cset[0]] = os[i];
710			}
711			}
712	greg	2.3	if (!(os[0] = k)) /* new "to check" set size */
713			return; /* special case */
714	greg	2.2	while (j <= cs[0]) /* get the rest of cs */
715			cset[++cset[0]] = cs[j++];
716	greg	2.3	if (cset[0] > MAXCSET) /* truncate "checked" set if nec. */
717	greg	2.2	cset[0] = MAXCSET;
718	greg	2.3	/* setcopy(cs, cset); / / copy cset back to cs */
719			os = cset;
720			for (i = os[0]; i-- >= 0; )
721			cs++ = os++;
722	greg	1.1	}