src/rt/raytrace.c

#ifndef lint
static const char RCSid[] = "$Id: raytrace.c,v 2.52 2005/06/21 15:06:50 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"

#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 RREAL  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 */

#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);


extern 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 (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);
        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->rlvl <= maxdepth && r->rweight >= minweight ? 0 : -1);
}


extern void
rayclear(                       /* clear a ray for (re)evaluation */
        register RAY  *r
)
{
        r->rno = raynum++;
        r->newcset = r->clipset;
        r->hitf = rayhit;
        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;
        r->uv[0] = r->uv[1] = 0.0;
        setcolor(r->pcol, 1.0, 1.0, 1.0);
        setcolor(r->rcol, 0.0, 0.0, 0.0);
}


extern 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 */
}


extern void
raycont(                        /* 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);
}


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

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


extern int
rayshade(               /* shade ray r with material mod */
        register RAY  *r,
        int  mod
)
{
        register OBJREC  *m;

        r->rt = r->rot;                 /* set 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 (do_irrad && !(r->crtype & ~(PRIMARY|TRANS)) &&
                                m->otype != MAT_CLIP &&
                                (ofun[m->otype].flags & (T_M|T_X))) {
                        if (irr_ignore(m->otype)) {
                                raytrans(r);
                                return(1);
                        }
                        if (!islight(m->otype))
                                m = &Lamb;
                }
                if ((*ofun[m->otype].funp)(m, r))
                        return(1);      /* materials call raytexture() */
        }
        return(0);                      /* no material! */
}


extern void
rayparticipate(                 /* 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<=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 */
        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 */
}


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


extern int
raymixture(             /* mix modifiers */
        register RAY  *r,
        OBJECT  fore,
        OBJECT  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 */
        fr = *r;
        if (coef > FTINY)
                foremat = rayshade(&fr, fore);
                                        /* background */
        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);
}


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

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


extern void
raycontrib(             /* compute (cumulative) ray contribution */
        double  rc[3],
        const RAY  *r,
        int  flags
)
{
        double  eext[3];
        int     i;

        eext[0] = eext[1] = eext[2] = 0.;
        rc[0] = rc[1] = rc[2] = 1.;

        while (r != NULL && r->crtype&flags) {
                for (i = 3; i--; ) {
                        rc[i] *= colval(r->rcoef,i);
                        eext[i] += r->rot * colval(r->cext,i);
                }
                r = r->parent;
        }
        for (i = 3; i--; )
                rc[i] *= (eext[i] <= FTINY) ? 1. :
                                (eext[i] > 92.) ? 0. : exp(-eext[i]);
}


extern double
raynormal(              /* 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);
}


extern void
newrayxf(                       /* 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 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 *)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;
}


extern void
flipsurface(                    /* 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];
}


extern 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];
        }
}


extern int
localhit(               /* 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(                /* 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(               /* check for hit in full cube */
        register 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 */
        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:	2.53
Committed:	Thu Jun 23 09:11:38 2005 UTC (18 years, 10 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.52:	+9 -4 lines
Log Message:	Added check to avoid exp underflow
#	User	Rev	Content
1	greg	1.1	#ifndef lint
2	greg	2.53	static const char RCSid[] = "$Id: raytrace.c,v 2.52 2005/06/21 15:06:50 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	1.15
18	greg	2.3	#define MAXCSET ((MAXSET+1)2-1) / maximum check set size */
19
20	greg	2.6	unsigned long raynum = 0; /* next unique ray number */
21			unsigned long nrays = 0; /* number of calls to localhit */
22	greg	1.1
23	schorsch	2.40	static RREAL Lambfa[5] = {PI, PI, PI, 0.0, 0.0};
24	greg	1.15	OBJREC Lamb = {
25			OVOID, MAT_PLASTIC, "Lambertian",
26	greg	2.2	{0, 5, NULL, Lambfa}, NULL,
27	greg	1.15	}; /* a Lambertian surface */
28
29	greg	2.17	OBJREC Aftplane; /* aft clipping plane object */
30	greg	2.16
31	schorsch	2.45	#define RAYHIT (-1) /* return value for intercepted ray */
32	greg	2.5
33	schorsch	2.45	static int raymove(FVECT pos, OBJECT cxs, int dirf, RAY r, CUBE *cu);
34			static int checkhit(RAY r, CUBE cu, OBJECT *cxs);
35			static void checkset(OBJECT os, OBJECT cs);
36	greg	1.1
37
38	schorsch	2.45	extern int
39			rayorigin( /* start new ray from old one */
40	greg	2.49	RAY *r,
41	schorsch	2.45	int rt,
42	greg	2.49	const RAY *ro,
43			const COLOR rc
44	schorsch	2.45	)
45	greg	1.1	{
46	greg	2.49	double rw, re;
47			/* assign coefficient/weight */
48			if (rc == NULL) {
49			rw = 1.0;
50			setcolor(r->rcoef, 1., 1., 1.);
51			} else {
52			rw = intens(rc);
53			if (rc != r->rcoef)
54			copycolor(r->rcoef, rc);
55			}
56	greg	1.1	if ((r->parent = ro) == NULL) { /* primary ray */
57			r->rlvl = 0;
58			r->rweight = rw;
59			r->crtype = r->rtype = rt;
60			r->rsrc = -1;
61			r->clipset = NULL;
62	greg	2.50	r->revf = raytrace;
63	greg	2.23	copycolor(r->cext, cextinction);
64	greg	2.26	copycolor(r->albedo, salbedo);
65	greg	2.23	r->gecc = seccg;
66			r->slights = NULL;
67	greg	1.1	} else { /* spawned ray */
68	greg	2.49	if (ro->rot >= FHUGE) {
69			memset(r, 0, sizeof(RAY));
70			return(-1); /* illegal continuation */
71			}
72	greg	1.1	r->rlvl = ro->rlvl;
73			if (rt & RAYREFL) {
74			r->rlvl++;
75			r->rsrc = -1;
76			r->clipset = ro->clipset;
77	greg	2.22	r->rmax = 0.0;
78	greg	1.1	} else {
79			r->rsrc = ro->rsrc;
80			r->clipset = ro->newcset;
81	greg	2.22	r->rmax = ro->rmax <= FTINY ? 0.0 : ro->rmax - ro->rot;
82	greg	1.1	}
83	greg	2.50	r->revf = ro->revf;
84	greg	2.23	copycolor(r->cext, ro->cext);
85	greg	2.26	copycolor(r->albedo, ro->albedo);
86	greg	2.23	r->gecc = ro->gecc;
87			r->slights = ro->slights;
88	greg	1.1	r->crtype = ro->crtype \| (r->rtype = rt);
89			VCOPY(r->rorg, ro->rop);
90	gwlarson	2.31	r->rweight = ro->rweight * rw;
91	greg	2.49	/* estimate extinction */
92	gwlarson	2.31	re = colval(ro->cext,RED) < colval(ro->cext,GRN) ?
93			colval(ro->cext,RED) : colval(ro->cext,GRN);
94			if (colval(ro->cext,BLU) < re) re = colval(ro->cext,BLU);
95	greg	2.49	re *= ro->rot;
96	greg	2.53	if (re > 0.1)
97			if (re > 92.)
98			r->rweight = 0.0;
99			else
100			r->rweight *= exp(-re);
101	greg	1.1	}
102	greg	1.22	rayclear(r);
103	greg	2.53	if (r->rweight <= 0.0) /* check for expiration */
104			return(-1);
105	greg	2.52	if (r->crtype & SHADOW) /* shadow commitment */
106			return(0);
107	greg	2.51	if (maxdepth <= 0 && rc != NULL) { /* Russian roulette */
108			if (minweight <= 0.0)
109			error(USER, "zero ray weight in Russian roulette");
110			if (maxdepth < 0 && r->rlvl > -maxdepth)
111			return(-1); /* upper reflection limit */
112			if (r->rweight >= minweight)
113			return(0);
114			if (frandom() < r->rweight/minweight)
115			return(-1);
116			rw = minweight/r->rweight; /* promote survivor */
117			scalecolor(r->rcoef, rw);
118			r->rweight = minweight;
119			return(0);
120			}
121	greg	1.22	return(r->rlvl <= maxdepth && r->rweight >= minweight ? 0 : -1);
122			}
123
124
125	schorsch	2.45	extern void
126			rayclear( /* clear a ray for (re)evaluation */
127			register RAY *r
128			)
129	greg	1.22	{
130	greg	1.20	r->rno = raynum++;
131	greg	1.1	r->newcset = r->clipset;
132	greg	2.36	r->hitf = rayhit;
133	greg	2.28	r->robj = OVOID;
134	greg	2.17	r->ro = NULL;
135	greg	2.34	r->rox = NULL;
136	gregl	2.29	r->rt = r->rot = FHUGE;
137	greg	1.1	r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
138	greg	2.37	r->uv[0] = r->uv[1] = 0.0;
139	greg	1.1	setcolor(r->pcol, 1.0, 1.0, 1.0);
140			setcolor(r->rcol, 0.0, 0.0, 0.0);
141			}
142
143
144	schorsch	2.45	extern void
145	greg	2.50	raytrace( /* trace a ray and compute its value */
146	schorsch	2.45	RAY *r
147			)
148	greg	1.1	{
149	greg	1.15	if (localhit(r, &thescene))
150	greg	2.24	raycont(r); /* hit local surface, evaluate */
151	greg	2.16	else if (r->ro == &Aftplane) {
152	greg	2.23	r->ro = NULL; /* hit aft clipping plane */
153	greg	2.16	r->rot = FHUGE;
154			} else if (sourcehit(r))
155	greg	2.24	rayshade(r, r->ro->omod); /* distant source */
156	greg	1.1
157			if (trace != NULL)
158			(trace)(r); / trace execution */
159	greg	2.49
160			rayparticipate(r); /* for participating medium */
161	greg	1.1	}
162
163
164	schorsch	2.45	extern void
165			raycont( /* check for clipped object and continue */
166			register RAY *r
167			)
168	greg	1.8	{
169	greg	2.7	if ((r->clipset != NULL && inset(r->clipset, r->ro->omod)) \|\|
170	greg	2.24	!rayshade(r, r->ro->omod))
171	greg	1.8	raytrans(r);
172			}
173
174
175	schorsch	2.45	extern void
176			raytrans( /* transmit ray as is */
177			register RAY *r
178			)
179	greg	1.1	{
180			RAY tr;
181
182	greg	2.49	if (rayorigin(&tr, TRANS, r, NULL) == 0) {
183	greg	1.1	VCOPY(tr.rdir, r->rdir);
184			rayvalue(&tr);
185			copycolor(r->rcol, tr.rcol);
186	greg	1.10	r->rt = r->rot + tr.rt;
187	greg	1.1	}
188			}
189
190
191	schorsch	2.45	extern int
192			rayshade( /* shade ray r with material mod */
193			register RAY *r,
194			int mod
195			)
196	greg	1.1	{
197			register OBJREC *m;
198	greg	2.47
199	greg	1.19	r->rt = r->rot; /* set effective ray length */
200	greg	2.47	for ( ; mod != OVOID; mod = m->omod) {
201	greg	1.1	m = objptr(mod);
202	greg	1.4	/****** unnecessary test since modifier() is always called
203	greg	1.1	if (!ismodifier(m->otype)) {
204			sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
205			error(USER, errmsg);
206			}
207	greg	1.4	******/
208	greg	1.16	/* hack for irradiance calculation */
209	greg	2.38	if (do_irrad && !(r->crtype & ~(PRIMARY\|TRANS)) &&
210	greg	2.43	m->otype != MAT_CLIP &&
211	greg	2.38	(ofun[m->otype].flags & (T_M\|T_X))) {
212	greg	1.16	if (irr_ignore(m->otype)) {
213			raytrans(r);
214	greg	2.15	return(1);
215	greg	1.16	}
216	greg	1.18	if (!islight(m->otype))
217	greg	1.16	m = &Lamb;
218			}
219	greg	2.47	if ((*ofun[m->otype].funp)(m, r))
220			return(1); /* materials call raytexture() */
221	greg	1.1	}
222	greg	2.47	return(0); /* no material! */
223	greg	2.23	}
224
225
226	schorsch	2.45	extern void
227			rayparticipate( /* compute ray medium participation */
228			register RAY *r
229			)
230	greg	2.23	{
231			COLOR ce, ca;
232			double re, ge, be;
233
234			if (intens(r->cext) <= 1./FHUGE)
235			return; /* no medium */
236	greg	2.27	re = r->rot*colval(r->cext,RED);
237			ge = r->rot*colval(r->cext,GRN);
238			be = r->rot*colval(r->cext,BLU);
239	greg	2.26	if (r->crtype & SHADOW) { /* no scattering for sources */
240			re *= 1. - colval(r->albedo,RED);
241			ge *= 1. - colval(r->albedo,GRN);
242			be *= 1. - colval(r->albedo,BLU);
243			}
244	greg	2.49	setcolor(ce, re<=FTINY ? 1. : re>92. ? 0. : exp(-re),
245			ge<=FTINY ? 1. : ge>92. ? 0. : exp(-ge),
246			be<=FTINY ? 1. : be>92. ? 0. : exp(-be));
247			multcolor(r->rcol, ce); /* path extinction */
248	greg	2.26	if (r->crtype & SHADOW \|\| intens(r->albedo) <= FTINY)
249	greg	2.23	return; /* no scattering */
250	greg	2.26	setcolor(ca,
251			colval(r->albedo,RED)colval(ambval,RED)(1.-colval(ce,RED)),
252			colval(r->albedo,GRN)colval(ambval,GRN)(1.-colval(ce,GRN)),
253			colval(r->albedo,BLU)colval(ambval,BLU)(1.-colval(ce,BLU)));
254	greg	2.23	addcolor(r->rcol, ca); /* ambient in scattering */
255			srcscatter(r); /* source in scattering */
256	greg	1.1	}
257
258
259	schorsch	2.45	extern void
260			raytexture( /* get material modifiers */
261			RAY *r,
262			OBJECT mod
263			)
264	greg	1.1	{
265	gwlarson	2.33	register OBJREC *m;
266	greg	1.1	/* execute textures and patterns */
267			for ( ; mod != OVOID; mod = m->omod) {
268			m = objptr(mod);
269	greg	2.9	/****** unnecessary test since modifier() is always called
270			if (!ismodifier(m->otype)) {
271	greg	1.1	sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
272			error(USER, errmsg);
273			}
274	greg	2.9	******/
275	greg	2.20	if ((*ofun[m->otype].funp)(m, r)) {
276			sprintf(errmsg, "conflicting material \"%s\"",
277			m->oname);
278			objerror(r->ro, USER, errmsg);
279			}
280	greg	1.1	}
281			}
282
283
284	schorsch	2.45	extern int
285			raymixture( /* mix modifiers */
286			register RAY *r,
287			OBJECT fore,
288			OBJECT back,
289			double coef
290			)
291	greg	1.1	{
292	greg	2.9	RAY fr, br;
293			int foremat, backmat;
294	greg	1.1	register int i;
295	greg	2.24	/* bound coefficient */
296	greg	1.1	if (coef > 1.0)
297			coef = 1.0;
298			else if (coef < 0.0)
299			coef = 0.0;
300	greg	2.13	/* compute foreground and background */
301	greg	2.24	foremat = backmat = 0;
302	greg	2.9	/* foreground */
303	schorsch	2.41	fr = *r;
304	greg	2.24	if (coef > FTINY)
305	greg	2.9	foremat = rayshade(&fr, fore);
306			/* background */
307	schorsch	2.41	br = *r;
308	greg	2.24	if (coef < 1.0-FTINY)
309	greg	2.9	backmat = rayshade(&br, back);
310	greg	2.24	/* check for transparency */
311	schorsch	2.41	if (backmat ^ foremat) {
312	gwlarson	2.33	if (backmat && coef > FTINY)
313	greg	2.24	raytrans(&fr);
314	gwlarson	2.33	else if (foremat && coef < 1.0-FTINY)
315	greg	2.24	raytrans(&br);
316	schorsch	2.41	}
317	greg	2.12	/* mix perturbations */
318	greg	1.1	for (i = 0; i < 3; i++)
319	greg	2.12	r->pert[i] = coeffr.pert[i] + (1.0-coef)br.pert[i];
320			/* mix pattern colors */
321	greg	2.9	scalecolor(fr.pcol, coef);
322			scalecolor(br.pcol, 1.0-coef);
323	greg	2.12	copycolor(r->pcol, fr.pcol);
324			addcolor(r->pcol, br.pcol);
325	greg	2.24	/* return value tells if material */
326			if (!foremat & !backmat)
327			return(0);
328	greg	2.12	/* mix returned ray values */
329	greg	2.24	scalecolor(fr.rcol, coef);
330			scalecolor(br.rcol, 1.0-coef);
331			copycolor(r->rcol, fr.rcol);
332			addcolor(r->rcol, br.rcol);
333			r->rt = bright(fr.rcol) > bright(br.rcol) ? fr.rt : br.rt;
334			return(1);
335	greg	1.1	}
336
337
338	schorsch	2.45	extern double
339			raydist( /* compute (cumulative) ray distance */
340	greg	2.49	register const RAY *r,
341	schorsch	2.45	register int flags
342			)
343	greg	2.21	{
344			double sum = 0.0;
345
346			while (r != NULL && r->crtype&flags) {
347			sum += r->rot;
348			r = r->parent;
349			}
350			return(sum);
351			}
352
353
354	greg	2.49	extern void
355			raycontrib( /* compute (cumulative) ray contribution */
356	greg	2.52	double rc[3],
357	greg	2.49	const RAY *r,
358			int flags
359			)
360			{
361	greg	2.52	double eext[3];
362			int i;
363
364			eext[0] = eext[1] = eext[2] = 0.;
365			rc[0] = rc[1] = rc[2] = 1.;
366	greg	2.49
367			while (r != NULL && r->crtype&flags) {
368	greg	2.52	for (i = 3; i--; ) {
369			rc[i] *= colval(r->rcoef,i);
370			eext[i] += r->rot * colval(r->cext,i);
371			}
372	greg	2.49	r = r->parent;
373			}
374	greg	2.52	for (i = 3; i--; )
375			rc[i] *= (eext[i] <= FTINY) ? 1. :
376	greg	2.53	(eext[i] > 92.) ? 0. : exp(-eext[i]);
377	greg	2.49	}
378
379
380	schorsch	2.45	extern double
381			raynormal( /* compute perturbed normal for ray */
382			FVECT norm,
383			register RAY *r
384			)
385	greg	1.1	{
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	schorsch	2.45	extern void
417			newrayxf( /* get new tranformation matrix for ray */
418			RAY *r
419			)
420	greg	1.12	{
421			static struct xfn {
422			struct xfn *next;
423			FULLXF xf;
424			} xfseed = { &xfseed }, *xflast = &xfseed;
425			register struct xfn *xp;
426	greg	2.49	register const RAY *rp;
427	greg	1.12
428			/*
429			* Search for transform in circular list that
430			* has no associated ray in the tree.
431			*/
432			xp = xflast;
433			for (rp = r->parent; rp != NULL; rp = rp->parent)
434			if (rp->rox == &xp->xf) { /* xp in use */
435			xp = xp->next; /* move to next */
436			if (xp == xflast) { /* need new one */
437	greg	2.34	xp = (struct xfn *)malloc(sizeof(struct xfn));
438	greg	1.12	if (xp == NULL)
439			error(SYSTEM,
440			"out of memory in newrayxf");
441			/* insert in list */
442			xp->next = xflast->next;
443			xflast->next = xp;
444			break; /* we're done */
445			}
446			rp = r; /* start check over */
447			}
448			/* got it */
449			r->rox = &xp->xf;
450			xflast = xp;
451	greg	1.1	}
452
453
454	schorsch	2.45	extern void
455			flipsurface( /* reverse surface orientation */
456			register RAY *r
457			)
458	greg	1.1	{
459			r->rod = -r->rod;
460			r->ron[0] = -r->ron[0];
461			r->ron[1] = -r->ron[1];
462			r->ron[2] = -r->ron[2];
463			r->pert[0] = -r->pert[0];
464			r->pert[1] = -r->pert[1];
465			r->pert[2] = -r->pert[2];
466			}
467
468
469	schorsch	2.45	extern void
470			rayhit( /* standard ray hit test */
471			OBJECT *oset,
472			RAY *r
473			)
474	greg	2.36	{
475			OBJREC *o;
476			int i;
477
478			for (i = oset[0]; i > 0; i--) {
479			o = objptr(oset[i]);
480			if ((*ofun[o->otype].funp)(o, r))
481			r->robj = oset[i];
482			}
483			}
484
485
486	schorsch	2.45	extern int
487			localhit( /* check for hit in the octree */
488			register RAY *r,
489			register CUBE *scene
490			)
491	greg	1.1	{
492	greg	2.3	OBJECT cxset[MAXCSET+1]; /* set of checked objects */
493	greg	1.1	FVECT curpos; /* current cube position */
494	greg	1.11	int sflags; /* sign flags */
495	greg	1.1	double t, dt;
496			register int i;
497
498	greg	1.21	nrays++; /* increment trace counter */
499	greg	1.11	sflags = 0;
500	greg	1.1	for (i = 0; i < 3; i++) {
501			curpos[i] = r->rorg[i];
502	greg	2.8	if (r->rdir[i] > 1e-7)
503	greg	1.11	sflags \|= 1 << i;
504	greg	2.8	else if (r->rdir[i] < -1e-7)
505	greg	1.11	sflags \|= 0x10 << i;
506	greg	1.1	}
507	greg	1.17	if (sflags == 0)
508			error(CONSISTENCY, "zero ray direction in localhit");
509	greg	2.17	/* start off assuming nothing hit */
510			if (r->rmax > FTINY) { /* except aft plane if one */
511			r->ro = &Aftplane;
512			r->rot = r->rmax;
513			for (i = 0; i < 3; i++)
514			r->rop[i] = r->rorg[i] + r->rot*r->rdir[i];
515			}
516			/* find global cube entrance point */
517	greg	1.1	t = 0.0;
518			if (!incube(scene, curpos)) {
519			/* find distance to entry */
520			for (i = 0; i < 3; i++) {
521			/* plane in our direction */
522	greg	1.11	if (sflags & 1<<i)
523	greg	1.1	dt = scene->cuorg[i];
524	greg	1.11	else if (sflags & 0x10<<i)
525	greg	1.1	dt = scene->cuorg[i] + scene->cusize;
526			else
527			continue;
528			/* distance to the plane */
529			dt = (dt - r->rorg[i])/r->rdir[i];
530			if (dt > t)
531			t = dt; /* farthest face is the one */
532			}
533			t += FTINY; /* fudge to get inside cube */
534	greg	2.17	if (t >= r->rot) /* clipped already */
535			return(0);
536	greg	1.1	/* advance position */
537			for (i = 0; i < 3; i++)
538			curpos[i] += r->rdir[i]*t;
539
540			if (!incube(scene, curpos)) /* non-intersecting ray */
541			return(0);
542			}
543	greg	2.3	cxset[0] = 0;
544	greg	2.19	raymove(curpos, cxset, sflags, r, scene);
545	schorsch	2.42	return((r->ro != NULL) & (r->ro != &Aftplane));
546	greg	1.1	}
547
548
549			static int
550	schorsch	2.45	raymove( /* check for hit as we move */
551			FVECT pos, /* current position, modified herein */
552			OBJECT cxs, / checked objects, modified by checkhit */
553			int dirf, /* direction indicators to speed tests */
554			register RAY *r,
555			register CUBE *cu
556			)
557	greg	1.1	{
558			int ax;
559			double dt, t;
560
561			if (istree(cu->cutree)) { /* recurse on subcubes */
562			CUBE cukid;
563	greg	1.11	register int br, sgn;
564	greg	1.1
565			cukid.cusize = cu->cusize * 0.5; /* find subcube */
566			VCOPY(cukid.cuorg, cu->cuorg);
567			br = 0;
568			if (pos[0] >= cukid.cuorg[0]+cukid.cusize) {
569			cukid.cuorg[0] += cukid.cusize;
570			br \|= 1;
571			}
572			if (pos[1] >= cukid.cuorg[1]+cukid.cusize) {
573			cukid.cuorg[1] += cukid.cusize;
574			br \|= 2;
575			}
576			if (pos[2] >= cukid.cuorg[2]+cukid.cusize) {
577			cukid.cuorg[2] += cukid.cusize;
578			br \|= 4;
579			}
580			for ( ; ; ) {
581			cukid.cutree = octkid(cu->cutree, br);
582	greg	2.3	if ((ax = raymove(pos,cxs,dirf,r,&cukid)) == RAYHIT)
583	greg	1.1	return(RAYHIT);
584			sgn = 1 << ax;
585	greg	1.11	if (sgn & dirf) /* positive axis? */
586	greg	1.1	if (sgn & br)
587			return(ax); /* overflow */
588			else {
589			cukid.cuorg[ax] += cukid.cusize;
590			br \|= sgn;
591			}
592	greg	1.11	else
593			if (sgn & br) {
594			cukid.cuorg[ax] -= cukid.cusize;
595			br &= ~sgn;
596			} else
597			return(ax); /* underflow */
598	greg	1.1	}
599			/NOTREACHED/
600			}
601	greg	2.18	if (isfull(cu->cutree)) {
602			if (checkhit(r, cu, cxs))
603			return(RAYHIT);
604			} else if (r->ro == &Aftplane && incube(cu, r->rop))
605	greg	1.1	return(RAYHIT);
606			/* advance to next cube */
607	greg	1.11	if (dirf&0x11) {
608			dt = dirf&1 ? cu->cuorg[0] + cu->cusize : cu->cuorg[0];
609	greg	1.1	t = (dt - pos[0])/r->rdir[0];
610			ax = 0;
611			} else
612			t = FHUGE;
613	greg	1.11	if (dirf&0x22) {
614			dt = dirf&2 ? cu->cuorg[1] + cu->cusize : cu->cuorg[1];
615	greg	1.1	dt = (dt - pos[1])/r->rdir[1];
616			if (dt < t) {
617			t = dt;
618			ax = 1;
619			}
620			}
621	greg	1.11	if (dirf&0x44) {
622			dt = dirf&4 ? cu->cuorg[2] + cu->cusize : cu->cuorg[2];
623	greg	1.1	dt = (dt - pos[2])/r->rdir[2];
624			if (dt < t) {
625			t = dt;
626			ax = 2;
627			}
628			}
629			pos[0] += r->rdir[0]*t;
630			pos[1] += r->rdir[1]*t;
631			pos[2] += r->rdir[2]*t;
632			return(ax);
633			}
634
635
636	greg	2.34	static int
637	schorsch	2.45	checkhit( /* check for hit in full cube */
638			register RAY *r,
639			CUBE *cu,
640			OBJECT *cxs
641			)
642	greg	1.1	{
643			OBJECT oset[MAXSET+1];
644
645			objset(oset, cu->cutree);
646	greg	2.36	checkset(oset, cxs); /* avoid double-checking */
647
648			(r->hitf)(oset, r); / test for hit in set */
649
650			if (r->robj == OVOID)
651	greg	1.1	return(0); /* no scores yet */
652
653			return(incube(cu, r->rop)); /* hit OK if in current cube */
654	greg	2.2	}
655
656
657	greg	2.34	static void
658	schorsch	2.45	checkset( /* modify checked set and set to check */
659			register OBJECT os, / os' = os - cs */
660			register OBJECT cs / cs' = cs + os */
661			)
662	greg	2.2	{
663			OBJECT cset[MAXCSET+MAXSET+1];
664	greg	2.3	register int i, j;
665			int k;
666	greg	2.2	/* copy os in place, cset <- cs */
667			cset[0] = 0;
668			k = 0;
669			for (i = j = 1; i <= os[0]; i++) {
670			while (j <= cs[0] && cs[j] < os[i])
671			cset[++cset[0]] = cs[j++];
672			if (j > cs[0] \|\| os[i] != cs[j]) { /* object to check */
673			os[++k] = os[i];
674			cset[++cset[0]] = os[i];
675			}
676			}
677	greg	2.3	if (!(os[0] = k)) /* new "to check" set size */
678			return; /* special case */
679	greg	2.2	while (j <= cs[0]) /* get the rest of cs */
680			cset[++cset[0]] = cs[j++];
681	greg	2.3	if (cset[0] > MAXCSET) /* truncate "checked" set if nec. */
682	greg	2.2	cset[0] = MAXCSET;
683	greg	2.3	/* setcopy(cs, cset); / / copy cset back to cs */
684			os = cset;
685			for (i = os[0]; i-- >= 0; )
686			cs++ = os++;
687	greg	1.1	}