src/rt/raytrace.c

/* Copyright (c) 1996 Regents of the University of California */

#ifndef lint
static char SCCSid[] = "$SunId$ LBL";
#endif

/*
 *  raytrace.c - routines for tracing and shading rays.
 *
 *     8/7/85
 */

#include  "ray.h"

#include  "octree.h"

#include  "otypes.h"

#include  "otspecial.h"

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

extern CUBE  thescene;                  /* our scene */
extern int  maxdepth;                   /* maximum recursion depth */
extern double  minweight;               /* minimum ray weight */
extern int  do_irrad;                   /* compute irradiance? */
extern COLOR  ambval;                   /* ambient value */

extern COLOR  cextinction;              /* global extinction coefficient */
extern COLOR  salbedo;                  /* global scattering albedo */
extern double  seccg;                   /* global scattering eccentricity */
extern double  ssampdist;               /* scatter sampling distance */

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(), checkset(), checkhit();

#define  MAXLOOP        128             /* modifier loop detection */

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


rayorigin(r, ro, rt, rw)                /* start new ray from old one */
register RAY  *r, *ro;
int  rt;
double  rw;
{
        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->rweight = ro->rweight * rw;
                r->crtype = ro->crtype | (r->rtype = rt);
                VCOPY(r->rorg, ro->rop);
        }
        rayclear(r);
        return(r->rlvl <= maxdepth && r->rweight >= minweight ? 0 : -1);
}


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->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);
        r->rt = 0.0;
}


raytrace(r)                     /* trace a ray and compute its value */
RAY  *r;
{
        extern int  (*trace)();

        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 */
}


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);
}


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;
        }
}


rayshade(r, mod)                /* shade ray r with material mod */
register RAY  *r;
int  mod;
{
        static int  depth = 0;
        int  gotmat;
        register OBJREC  *m;
                                        /* check for infinite loop */
        if (depth++ >= MAXLOOP)
                objerror(r->ro, USER, "possible modifier loop");
        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)) {
                                depth--;
                                raytrans(r);
                                return(1);
                        }
                        if (!islight(m->otype))
                                m = &Lamb;
                }
                                        /* materials call raytexture */
                gotmat = (*ofun[m->otype].funp)(m, r);
        }
        depth--;
        return(gotmat);
}


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;
{
        static int  depth = 0;
        register OBJREC  *m;
                                        /* check for infinite loop */
        if (depth++ >= MAXLOOP)
                objerror(r->ro, USER, "modifier loop");
                                        /* 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);
                }
        }
        depth--;                        /* end here */
}


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)
                        raytrans(&fr);
                else
                        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);
}


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 *)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;
}


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];
}


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
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
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:	2.28
Committed:	Fri Mar 7 16:58:54 1997 UTC (27 years, 2 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.27:	+3 -1 lines
Log Message:	added object number to ray structure for instance tracking
#	User	Rev	Content
1	greg	2.25	/* Copyright (c) 1996 Regents of the University of California */
2	greg	1.1
3			#ifndef lint
4			static char SCCSid[] = "$SunId$ LBL";
5			#endif
6
7			/*
8			* raytrace.c - routines for tracing and shading rays.
9			*
10			* 8/7/85
11			*/
12
13			#include "ray.h"
14
15			#include "octree.h"
16
17			#include "otypes.h"
18
19	greg	1.15	#include "otspecial.h"
20
21	greg	2.3	#define MAXCSET ((MAXSET+1)2-1) / maximum check set size */
22
23	greg	1.1	extern CUBE thescene; /* our scene */
24			extern int maxdepth; /* maximum recursion depth */
25			extern double minweight; /* minimum ray weight */
26	greg	1.15	extern int do_irrad; /* compute irradiance? */
27	greg	2.23	extern COLOR ambval; /* ambient value */
28	greg	1.1
29	greg	2.23	extern COLOR cextinction; /* global extinction coefficient */
30	greg	2.26	extern COLOR salbedo; /* global scattering albedo */
31	greg	2.23	extern double seccg; /* global scattering eccentricity */
32			extern double ssampdist; /* scatter sampling distance */
33
34	greg	2.6	unsigned long raynum = 0; /* next unique ray number */
35			unsigned long nrays = 0; /* number of calls to localhit */
36	greg	1.1
37	greg	1.23	static FLOAT Lambfa[5] = {PI, PI, PI, 0.0, 0.0};
38	greg	1.15	OBJREC Lamb = {
39			OVOID, MAT_PLASTIC, "Lambertian",
40	greg	2.2	{0, 5, NULL, Lambfa}, NULL,
41	greg	1.15	}; /* a Lambertian surface */
42
43	greg	2.17	OBJREC Aftplane; /* aft clipping plane object */
44	greg	2.16
45	greg	2.5	static int raymove(), checkset(), checkhit();
46
47	greg	1.6	#define MAXLOOP 128 /* modifier loop detection */
48	greg	1.1
49			#define RAYHIT (-1) /* return value for intercepted ray */
50
51
52			rayorigin(r, ro, rt, rw) /* start new ray from old one */
53			register RAY r, ro;
54			int rt;
55			double rw;
56			{
57			if ((r->parent = ro) == NULL) { /* primary ray */
58			r->rlvl = 0;
59			r->rweight = rw;
60			r->crtype = r->rtype = rt;
61			r->rsrc = -1;
62			r->clipset = NULL;
63	greg	1.21	r->revf = raytrace;
64	greg	2.23	copycolor(r->cext, cextinction);
65	greg	2.26	copycolor(r->albedo, salbedo);
66	greg	2.23	r->gecc = seccg;
67			r->slights = NULL;
68	greg	1.1	} else { /* spawned ray */
69			r->rlvl = ro->rlvl;
70			if (rt & RAYREFL) {
71			r->rlvl++;
72			r->rsrc = -1;
73			r->clipset = ro->clipset;
74	greg	2.22	r->rmax = 0.0;
75	greg	1.1	} else {
76			r->rsrc = ro->rsrc;
77			r->clipset = ro->newcset;
78	greg	2.22	r->rmax = ro->rmax <= FTINY ? 0.0 : ro->rmax - ro->rot;
79	greg	1.1	}
80	greg	1.21	r->revf = ro->revf;
81	greg	2.23	copycolor(r->cext, ro->cext);
82	greg	2.26	copycolor(r->albedo, ro->albedo);
83	greg	2.23	r->gecc = ro->gecc;
84			r->slights = ro->slights;
85	greg	1.1	r->rweight = ro->rweight * rw;
86			r->crtype = ro->crtype \| (r->rtype = rt);
87			VCOPY(r->rorg, ro->rop);
88			}
89	greg	1.22	rayclear(r);
90			return(r->rlvl <= maxdepth && r->rweight >= minweight ? 0 : -1);
91			}
92
93
94			rayclear(r) /* clear a ray for (re)evaluation */
95			register RAY *r;
96			{
97	greg	1.20	r->rno = raynum++;
98	greg	1.1	r->newcset = r->clipset;
99	greg	2.28	r->robj = OVOID;
100	greg	2.17	r->ro = NULL;
101			r->rot = FHUGE;
102	greg	1.1	r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
103			setcolor(r->pcol, 1.0, 1.0, 1.0);
104			setcolor(r->rcol, 0.0, 0.0, 0.0);
105	greg	1.10	r->rt = 0.0;
106	greg	1.1	}
107
108
109	greg	1.21	raytrace(r) /* trace a ray and compute its value */
110	greg	1.8	RAY *r;
111	greg	1.1	{
112			extern int (*trace)();
113
114	greg	1.15	if (localhit(r, &thescene))
115	greg	2.24	raycont(r); /* hit local surface, evaluate */
116	greg	2.16	else if (r->ro == &Aftplane) {
117	greg	2.23	r->ro = NULL; /* hit aft clipping plane */
118	greg	2.16	r->rot = FHUGE;
119			} else if (sourcehit(r))
120	greg	2.24	rayshade(r, r->ro->omod); /* distant source */
121	greg	1.1
122	greg	2.23	rayparticipate(r); /* for participating medium */
123
124	greg	1.1	if (trace != NULL)
125			(trace)(r); / trace execution */
126			}
127
128
129	greg	1.8	raycont(r) /* check for clipped object and continue */
130			register RAY *r;
131			{
132	greg	2.7	if ((r->clipset != NULL && inset(r->clipset, r->ro->omod)) \|\|
133	greg	2.24	!rayshade(r, r->ro->omod))
134	greg	1.8	raytrans(r);
135			}
136
137
138	greg	1.1	raytrans(r) /* transmit ray as is */
139	greg	1.8	register RAY *r;
140	greg	1.1	{
141			RAY tr;
142
143			if (rayorigin(&tr, r, TRANS, 1.0) == 0) {
144			VCOPY(tr.rdir, r->rdir);
145			rayvalue(&tr);
146			copycolor(r->rcol, tr.rcol);
147	greg	1.10	r->rt = r->rot + tr.rt;
148	greg	1.1	}
149			}
150
151
152			rayshade(r, mod) /* shade ray r with material mod */
153			register RAY *r;
154			int mod;
155			{
156			static int depth = 0;
157	greg	2.9	int gotmat;
158	greg	1.1	register OBJREC *m;
159			/* check for infinite loop */
160			if (depth++ >= MAXLOOP)
161	greg	1.4	objerror(r->ro, USER, "possible modifier loop");
162	greg	1.19	r->rt = r->rot; /* set effective ray length */
163	greg	2.9	for (gotmat = 0; !gotmat && mod != OVOID; mod = m->omod) {
164	greg	1.1	m = objptr(mod);
165	greg	1.4	/****** unnecessary test since modifier() is always called
166	greg	1.1	if (!ismodifier(m->otype)) {
167			sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
168			error(USER, errmsg);
169			}
170	greg	1.4	******/
171	greg	1.16	/* hack for irradiance calculation */
172			if (do_irrad && !(r->crtype & ~(PRIMARY\|TRANS))) {
173			if (irr_ignore(m->otype)) {
174			depth--;
175			raytrans(r);
176	greg	2.15	return(1);
177	greg	1.16	}
178	greg	1.18	if (!islight(m->otype))
179	greg	1.16	m = &Lamb;
180			}
181	greg	2.9	/* materials call raytexture */
182			gotmat = (*ofun[m->otype].funp)(m, r);
183	greg	1.1	}
184	greg	2.9	depth--;
185			return(gotmat);
186	greg	2.23	}
187
188
189			rayparticipate(r) /* compute ray medium participation */
190			register RAY *r;
191			{
192			COLOR ce, ca;
193			double re, ge, be;
194
195			if (intens(r->cext) <= 1./FHUGE)
196			return; /* no medium */
197	greg	2.27	re = r->rot*colval(r->cext,RED);
198			ge = r->rot*colval(r->cext,GRN);
199			be = r->rot*colval(r->cext,BLU);
200	greg	2.26	if (r->crtype & SHADOW) { /* no scattering for sources */
201			re *= 1. - colval(r->albedo,RED);
202			ge *= 1. - colval(r->albedo,GRN);
203			be *= 1. - colval(r->albedo,BLU);
204			}
205			setcolor(ce, re<=0. ? 1. : re>92. ? 0. : exp(-re),
206			ge<=0. ? 1. : ge>92. ? 0. : exp(-ge),
207			be<=0. ? 1. : be>92. ? 0. : exp(-be));
208	greg	2.23	multcolor(r->rcol, ce); /* path absorption */
209	greg	2.26	if (r->crtype & SHADOW \|\| intens(r->albedo) <= FTINY)
210	greg	2.23	return; /* no scattering */
211	greg	2.26	setcolor(ca,
212			colval(r->albedo,RED)colval(ambval,RED)(1.-colval(ce,RED)),
213			colval(r->albedo,GRN)colval(ambval,GRN)(1.-colval(ce,GRN)),
214			colval(r->albedo,BLU)colval(ambval,BLU)(1.-colval(ce,BLU)));
215	greg	2.23	addcolor(r->rcol, ca); /* ambient in scattering */
216			srcscatter(r); /* source in scattering */
217	greg	1.1	}
218
219
220			raytexture(r, mod) /* get material modifiers */
221			RAY *r;
222			int mod;
223			{
224			static int depth = 0;
225			register OBJREC *m;
226			/* check for infinite loop */
227			if (depth++ >= MAXLOOP)
228			objerror(r->ro, USER, "modifier loop");
229			/* execute textures and patterns */
230			for ( ; mod != OVOID; mod = m->omod) {
231			m = objptr(mod);
232	greg	2.9	/****** unnecessary test since modifier() is always called
233			if (!ismodifier(m->otype)) {
234	greg	1.1	sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
235			error(USER, errmsg);
236			}
237	greg	2.9	******/
238	greg	2.20	if ((*ofun[m->otype].funp)(m, r)) {
239			sprintf(errmsg, "conflicting material \"%s\"",
240			m->oname);
241			objerror(r->ro, USER, errmsg);
242			}
243	greg	1.1	}
244			depth--; /* end here */
245			}
246
247
248			raymixture(r, fore, back, coef) /* mix modifiers */
249			register RAY *r;
250			OBJECT fore, back;
251			double coef;
252			{
253	greg	2.9	RAY fr, br;
254			int foremat, backmat;
255	greg	1.1	register int i;
256	greg	2.24	/* bound coefficient */
257	greg	1.1	if (coef > 1.0)
258			coef = 1.0;
259			else if (coef < 0.0)
260			coef = 0.0;
261	greg	2.13	/* compute foreground and background */
262	greg	2.24	foremat = backmat = 0;
263	greg	2.9	/* foreground */
264			copystruct(&fr, r);
265	greg	2.24	if (coef > FTINY)
266	greg	2.9	foremat = rayshade(&fr, fore);
267			/* background */
268			copystruct(&br, r);
269	greg	2.24	if (coef < 1.0-FTINY)
270	greg	2.9	backmat = rayshade(&br, back);
271	greg	2.24	/* check for transparency */
272			if (backmat ^ foremat)
273			if (backmat)
274			raytrans(&fr);
275	greg	2.13	else
276	greg	2.24	raytrans(&br);
277	greg	2.12	/* mix perturbations */
278	greg	1.1	for (i = 0; i < 3; i++)
279	greg	2.12	r->pert[i] = coeffr.pert[i] + (1.0-coef)br.pert[i];
280			/* mix pattern colors */
281	greg	2.9	scalecolor(fr.pcol, coef);
282			scalecolor(br.pcol, 1.0-coef);
283	greg	2.12	copycolor(r->pcol, fr.pcol);
284			addcolor(r->pcol, br.pcol);
285	greg	2.24	/* return value tells if material */
286			if (!foremat & !backmat)
287			return(0);
288	greg	2.12	/* mix returned ray values */
289	greg	2.24	scalecolor(fr.rcol, coef);
290			scalecolor(br.rcol, 1.0-coef);
291			copycolor(r->rcol, fr.rcol);
292			addcolor(r->rcol, br.rcol);
293			r->rt = bright(fr.rcol) > bright(br.rcol) ? fr.rt : br.rt;
294			return(1);
295	greg	1.1	}
296
297
298			double
299	greg	2.21	raydist(r, flags) /* compute (cumulative) ray distance */
300			register RAY *r;
301			register int flags;
302			{
303			double sum = 0.0;
304
305			while (r != NULL && r->crtype&flags) {
306			sum += r->rot;
307			r = r->parent;
308			}
309			return(sum);
310			}
311
312
313			double
314	greg	1.1	raynormal(norm, r) /* compute perturbed normal for ray */
315			FVECT norm;
316			register RAY *r;
317			{
318			double newdot;
319			register int i;
320
321			/* The perturbation is added to the surface normal to obtain
322			* the new normal. If the new normal would affect the surface
323			* orientation wrt. the ray, a correction is made. The method is
324			* still fraught with problems since reflected rays and similar
325			* directions calculated from the surface normal may spawn rays behind
326			* the surface. The only solution is to curb textures at high
327	greg	1.9	* incidence (namely, keep DOT(rdir,pert) < Rdot).
328	greg	1.1	*/
329
330			for (i = 0; i < 3; i++)
331			norm[i] = r->ron[i] + r->pert[i];
332
333			if (normalize(norm) == 0.0) {
334			objerror(r->ro, WARNING, "illegal normal perturbation");
335			VCOPY(norm, r->ron);
336			return(r->rod);
337			}
338			newdot = -DOT(norm, r->rdir);
339			if ((newdot > 0.0) != (r->rod > 0.0)) { /* fix orientation */
340			for (i = 0; i < 3; i++)
341			norm[i] += 2.0newdotr->rdir[i];
342			newdot = -newdot;
343			}
344			return(newdot);
345	greg	1.12	}
346
347
348			newrayxf(r) /* get new tranformation matrix for ray */
349			RAY *r;
350			{
351			static struct xfn {
352			struct xfn *next;
353			FULLXF xf;
354			} xfseed = { &xfseed }, *xflast = &xfseed;
355			register struct xfn *xp;
356			register RAY *rp;
357
358			/*
359			* Search for transform in circular list that
360			* has no associated ray in the tree.
361			*/
362			xp = xflast;
363			for (rp = r->parent; rp != NULL; rp = rp->parent)
364			if (rp->rox == &xp->xf) { /* xp in use */
365			xp = xp->next; /* move to next */
366			if (xp == xflast) { /* need new one */
367	greg	1.14	xp = (struct xfn *)bmalloc(sizeof(struct xfn));
368	greg	1.12	if (xp == NULL)
369			error(SYSTEM,
370			"out of memory in newrayxf");
371			/* insert in list */
372			xp->next = xflast->next;
373			xflast->next = xp;
374			break; /* we're done */
375			}
376			rp = r; /* start check over */
377			}
378			/* got it */
379			r->rox = &xp->xf;
380			xflast = xp;
381	greg	1.1	}
382
383
384			flipsurface(r) /* reverse surface orientation */
385			register RAY *r;
386			{
387			r->rod = -r->rod;
388			r->ron[0] = -r->ron[0];
389			r->ron[1] = -r->ron[1];
390			r->ron[2] = -r->ron[2];
391			r->pert[0] = -r->pert[0];
392			r->pert[1] = -r->pert[1];
393			r->pert[2] = -r->pert[2];
394			}
395
396
397			localhit(r, scene) /* check for hit in the octree */
398			register RAY *r;
399			register CUBE *scene;
400			{
401	greg	2.3	OBJECT cxset[MAXCSET+1]; /* set of checked objects */
402	greg	1.1	FVECT curpos; /* current cube position */
403	greg	1.11	int sflags; /* sign flags */
404	greg	1.1	double t, dt;
405			register int i;
406
407	greg	1.21	nrays++; /* increment trace counter */
408	greg	1.11	sflags = 0;
409	greg	1.1	for (i = 0; i < 3; i++) {
410			curpos[i] = r->rorg[i];
411	greg	2.8	if (r->rdir[i] > 1e-7)
412	greg	1.11	sflags \|= 1 << i;
413	greg	2.8	else if (r->rdir[i] < -1e-7)
414	greg	1.11	sflags \|= 0x10 << i;
415	greg	1.1	}
416	greg	1.17	if (sflags == 0)
417			error(CONSISTENCY, "zero ray direction in localhit");
418	greg	2.17	/* start off assuming nothing hit */
419			if (r->rmax > FTINY) { /* except aft plane if one */
420			r->ro = &Aftplane;
421			r->rot = r->rmax;
422			for (i = 0; i < 3; i++)
423			r->rop[i] = r->rorg[i] + r->rot*r->rdir[i];
424			}
425			/* find global cube entrance point */
426	greg	1.1	t = 0.0;
427			if (!incube(scene, curpos)) {
428			/* find distance to entry */
429			for (i = 0; i < 3; i++) {
430			/* plane in our direction */
431	greg	1.11	if (sflags & 1<<i)
432	greg	1.1	dt = scene->cuorg[i];
433	greg	1.11	else if (sflags & 0x10<<i)
434	greg	1.1	dt = scene->cuorg[i] + scene->cusize;
435			else
436			continue;
437			/* distance to the plane */
438			dt = (dt - r->rorg[i])/r->rdir[i];
439			if (dt > t)
440			t = dt; /* farthest face is the one */
441			}
442			t += FTINY; /* fudge to get inside cube */
443	greg	2.17	if (t >= r->rot) /* clipped already */
444			return(0);
445	greg	1.1	/* advance position */
446			for (i = 0; i < 3; i++)
447			curpos[i] += r->rdir[i]*t;
448
449			if (!incube(scene, curpos)) /* non-intersecting ray */
450			return(0);
451			}
452	greg	2.3	cxset[0] = 0;
453	greg	2.19	raymove(curpos, cxset, sflags, r, scene);
454			return(r->ro != NULL & r->ro != &Aftplane);
455	greg	1.1	}
456
457
458			static int
459	greg	2.3	raymove(pos, cxs, dirf, r, cu) /* check for hit as we move */
460			FVECT pos; /* current position, modified herein */
461			OBJECT cxs; / checked objects, modified by checkhit */
462	greg	1.11	int dirf; /* direction indicators to speed tests */
463	greg	1.1	register RAY *r;
464			register CUBE *cu;
465			{
466			int ax;
467			double dt, t;
468
469			if (istree(cu->cutree)) { /* recurse on subcubes */
470			CUBE cukid;
471	greg	1.11	register int br, sgn;
472	greg	1.1
473			cukid.cusize = cu->cusize * 0.5; /* find subcube */
474			VCOPY(cukid.cuorg, cu->cuorg);
475			br = 0;
476			if (pos[0] >= cukid.cuorg[0]+cukid.cusize) {
477			cukid.cuorg[0] += cukid.cusize;
478			br \|= 1;
479			}
480			if (pos[1] >= cukid.cuorg[1]+cukid.cusize) {
481			cukid.cuorg[1] += cukid.cusize;
482			br \|= 2;
483			}
484			if (pos[2] >= cukid.cuorg[2]+cukid.cusize) {
485			cukid.cuorg[2] += cukid.cusize;
486			br \|= 4;
487			}
488			for ( ; ; ) {
489			cukid.cutree = octkid(cu->cutree, br);
490	greg	2.3	if ((ax = raymove(pos,cxs,dirf,r,&cukid)) == RAYHIT)
491	greg	1.1	return(RAYHIT);
492			sgn = 1 << ax;
493	greg	1.11	if (sgn & dirf) /* positive axis? */
494	greg	1.1	if (sgn & br)
495			return(ax); /* overflow */
496			else {
497			cukid.cuorg[ax] += cukid.cusize;
498			br \|= sgn;
499			}
500	greg	1.11	else
501			if (sgn & br) {
502			cukid.cuorg[ax] -= cukid.cusize;
503			br &= ~sgn;
504			} else
505			return(ax); /* underflow */
506	greg	1.1	}
507			/NOTREACHED/
508			}
509	greg	2.18	if (isfull(cu->cutree)) {
510			if (checkhit(r, cu, cxs))
511			return(RAYHIT);
512			} else if (r->ro == &Aftplane && incube(cu, r->rop))
513	greg	1.1	return(RAYHIT);
514			/* advance to next cube */
515	greg	1.11	if (dirf&0x11) {
516			dt = dirf&1 ? cu->cuorg[0] + cu->cusize : cu->cuorg[0];
517	greg	1.1	t = (dt - pos[0])/r->rdir[0];
518			ax = 0;
519			} else
520			t = FHUGE;
521	greg	1.11	if (dirf&0x22) {
522			dt = dirf&2 ? cu->cuorg[1] + cu->cusize : cu->cuorg[1];
523	greg	1.1	dt = (dt - pos[1])/r->rdir[1];
524			if (dt < t) {
525			t = dt;
526			ax = 1;
527			}
528			}
529	greg	1.11	if (dirf&0x44) {
530			dt = dirf&4 ? cu->cuorg[2] + cu->cusize : cu->cuorg[2];
531	greg	1.1	dt = (dt - pos[2])/r->rdir[2];
532			if (dt < t) {
533			t = dt;
534			ax = 2;
535			}
536			}
537			pos[0] += r->rdir[0]*t;
538			pos[1] += r->rdir[1]*t;
539			pos[2] += r->rdir[2]*t;
540			return(ax);
541			}
542
543
544			static
545	greg	2.3	checkhit(r, cu, cxs) /* check for hit in full cube */
546	greg	1.1	register RAY *r;
547			CUBE *cu;
548	greg	2.3	OBJECT *cxs;
549	greg	1.1	{
550			OBJECT oset[MAXSET+1];
551			register OBJREC *o;
552			register int i;
553
554			objset(oset, cu->cutree);
555	greg	2.3	checkset(oset, cxs); /* eliminate double-checking */
556	greg	1.1	for (i = oset[0]; i > 0; i--) {
557			o = objptr(oset[i]);
558	greg	2.28	if ((*ofun[o->otype].funp)(o, r))
559			r->robj = oset[i];
560	greg	1.1	}
561			if (r->ro == NULL)
562			return(0); /* no scores yet */
563
564			return(incube(cu, r->rop)); /* hit OK if in current cube */
565	greg	2.2	}
566
567
568			static
569			checkset(os, cs) /* modify checked set and set to check */
570	greg	2.3	register OBJECT os; / os' = os - cs */
571			register OBJECT cs; / cs' = cs + os */
572	greg	2.2	{
573			OBJECT cset[MAXCSET+MAXSET+1];
574	greg	2.3	register int i, j;
575			int k;
576	greg	2.2	/* copy os in place, cset <- cs */
577			cset[0] = 0;
578			k = 0;
579			for (i = j = 1; i <= os[0]; i++) {
580			while (j <= cs[0] && cs[j] < os[i])
581			cset[++cset[0]] = cs[j++];
582			if (j > cs[0] \|\| os[i] != cs[j]) { /* object to check */
583			os[++k] = os[i];
584			cset[++cset[0]] = os[i];
585			}
586			}
587	greg	2.3	if (!(os[0] = k)) /* new "to check" set size */
588			return; /* special case */
589	greg	2.2	while (j <= cs[0]) /* get the rest of cs */
590			cset[++cset[0]] = cs[j++];
591	greg	2.3	if (cset[0] > MAXCSET) /* truncate "checked" set if nec. */
592	greg	2.2	cset[0] = MAXCSET;
593	greg	2.3	/* setcopy(cs, cset); / / copy cset back to cs */
594			os = cset;
595			for (i = os[0]; i-- >= 0; )
596			cs++ = os++;
597	greg	1.1	}