src/rt/raytrace.c

/* Copyright (c) 1995 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 double  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);
                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);
                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->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)();
        int  gotmat;

        if (localhit(r, &thescene))
                gotmat = 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))
                gotmat = rayshade(r, r->ro->omod);      /* distant source */

        if (r->ro != NULL && !gotmat)
                objerror(r->ro, USER, "material not found");

        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)) ||
                        r->ro->omod == OVOID) {
                raytrans(r);
                return(1);
        }
        return(rayshade(r, r->ro->omod));
}


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  dist;
        double  re, ge, be;

        if (intens(r->cext) <= 1./FHUGE)
                return;                         /* no medium */
        if ((dist = r->rot) >= FHUGE)
                dist = 2.*thescene.cusize;      /* what to use for infinity? */
        if (r->crtype & SHADOW)
                dist *= 1. - salbedo;           /* no scattering for sources */
        if (dist <= FTINY)
                return;                         /* no effective ray travel */
        re = dist*colval(r->cext,RED);
        ge = dist*colval(r->cext,GRN);
        be = dist*colval(r->cext,BLU);
        setcolor(ce,    re>92. ? 0. : exp(-re),
                        ge>92. ? 0. : exp(-ge),
                        be>92. ? 0. : exp(-be));
        multcolor(r->rcol, ce);                 /* path absorption */
        if (r->albedo <= FTINY || r->crtype & SHADOW)
                return;                         /* no scattering */
        setcolor(ca,    salbedo*colval(ambval,RED)*(1.-colval(ce,RED)),
                        salbedo*colval(ambval,GRN)*(1.-colval(ce,GRN)),
                        salbedo*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;
                                        /* clip coefficient */
        if (coef > 1.0)
                coef = 1.0;
        else if (coef < 0.0)
                coef = 0.0;
                                        /* compute foreground and background */
        foremat = backmat = -1;
                                        /* foreground */
        copystruct(&fr, r);
        if (fore != OVOID && coef > FTINY)
                foremat = rayshade(&fr, fore);
                                        /* background */
        copystruct(&br, r);
        if (back != OVOID && coef < 1.0-FTINY)
                backmat = rayshade(&br, back);
                                        /* check */
        if (foremat < 0)
                if (backmat < 0)
                        foremat = backmat = 0;
                else
                        foremat = backmat;
        else if (backmat < 0)
                backmat = foremat;
        if ((foremat==0) != (backmat==0))
                objerror(r->ro, USER, "mixing material with non-material");
                                        /* 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);
                                        /* mix returned ray values */
        if (foremat) {
                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 value tells if material */
        return(foremat);
}


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]);
                (*ofun[o->otype].funp)(o, r);
        }
        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:	2.23
Committed:	Fri Dec 8 18:49:09 1995 UTC (28 years, 4 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.22:	+51 -3 lines
Log Message:	added M_MIST (mist) material and global participating medium
#	User	Rev	Content
1	greg	2.19	/* Copyright (c) 1995 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			extern double salbedo; /* global scattering albedo */
31			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			r->albedo = salbedo;
66			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			r->albedo = ro->albedo;
83			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	2.17	r->ro = NULL;
100			r->rot = FHUGE;
101	greg	1.1	r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
102			setcolor(r->pcol, 1.0, 1.0, 1.0);
103			setcolor(r->rcol, 0.0, 0.0, 0.0);
104	greg	1.10	r->rt = 0.0;
105	greg	1.1	}
106
107
108	greg	1.21	raytrace(r) /* trace a ray and compute its value */
109	greg	1.8	RAY *r;
110	greg	1.1	{
111			extern int (*trace)();
112	greg	2.9	int gotmat;
113	greg	1.1
114	greg	1.15	if (localhit(r, &thescene))
115	greg	2.23	gotmat = 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	2.23	gotmat = rayshade(r, r->ro->omod); /* distant source */
121	greg	1.1
122	greg	2.14	if (r->ro != NULL && !gotmat)
123	greg	2.9	objerror(r->ro, USER, "material not found");
124
125	greg	2.23	rayparticipate(r); /* for participating medium */
126
127	greg	1.1	if (trace != NULL)
128			(trace)(r); / trace execution */
129			}
130
131
132	greg	1.8	raycont(r) /* check for clipped object and continue */
133			register RAY *r;
134			{
135	greg	2.7	if ((r->clipset != NULL && inset(r->clipset, r->ro->omod)) \|\|
136	greg	2.9	r->ro->omod == OVOID) {
137	greg	1.8	raytrans(r);
138	greg	2.9	return(1);
139			}
140			return(rayshade(r, r->ro->omod));
141	greg	1.8	}
142
143
144	greg	1.1	raytrans(r) /* transmit ray as is */
145	greg	1.8	register RAY *r;
146	greg	1.1	{
147			RAY tr;
148
149			if (rayorigin(&tr, r, TRANS, 1.0) == 0) {
150			VCOPY(tr.rdir, r->rdir);
151			rayvalue(&tr);
152			copycolor(r->rcol, tr.rcol);
153	greg	1.10	r->rt = r->rot + tr.rt;
154	greg	1.1	}
155			}
156
157
158			rayshade(r, mod) /* shade ray r with material mod */
159			register RAY *r;
160			int mod;
161			{
162			static int depth = 0;
163	greg	2.9	int gotmat;
164	greg	1.1	register OBJREC *m;
165			/* check for infinite loop */
166			if (depth++ >= MAXLOOP)
167	greg	1.4	objerror(r->ro, USER, "possible modifier loop");
168	greg	1.19	r->rt = r->rot; /* set effective ray length */
169	greg	2.9	for (gotmat = 0; !gotmat && mod != OVOID; mod = m->omod) {
170	greg	1.1	m = objptr(mod);
171	greg	1.4	/****** unnecessary test since modifier() is always called
172	greg	1.1	if (!ismodifier(m->otype)) {
173			sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
174			error(USER, errmsg);
175			}
176	greg	1.4	******/
177	greg	1.16	/* hack for irradiance calculation */
178			if (do_irrad && !(r->crtype & ~(PRIMARY\|TRANS))) {
179			if (irr_ignore(m->otype)) {
180			depth--;
181			raytrans(r);
182	greg	2.15	return(1);
183	greg	1.16	}
184	greg	1.18	if (!islight(m->otype))
185	greg	1.16	m = &Lamb;
186			}
187	greg	2.9	/* materials call raytexture */
188			gotmat = (*ofun[m->otype].funp)(m, r);
189	greg	1.1	}
190	greg	2.9	depth--;
191			return(gotmat);
192	greg	2.23	}
193
194
195			rayparticipate(r) /* compute ray medium participation */
196			register RAY *r;
197			{
198			COLOR ce, ca;
199			double dist;
200			double re, ge, be;
201
202			if (intens(r->cext) <= 1./FHUGE)
203			return; /* no medium */
204			if ((dist = r->rot) >= FHUGE)
205			dist = 2.thescene.cusize; / what to use for infinity? */
206			if (r->crtype & SHADOW)
207			dist = 1. - salbedo; / no scattering for sources */
208			if (dist <= FTINY)
209			return; /* no effective ray travel */
210			re = dist*colval(r->cext,RED);
211			ge = dist*colval(r->cext,GRN);
212			be = dist*colval(r->cext,BLU);
213			setcolor(ce, re>92. ? 0. : exp(-re),
214			ge>92. ? 0. : exp(-ge),
215			be>92. ? 0. : exp(-be));
216			multcolor(r->rcol, ce); /* path absorption */
217			if (r->albedo <= FTINY \|\| r->crtype & SHADOW)
218			return; /* no scattering */
219			setcolor(ca, salbedocolval(ambval,RED)(1.-colval(ce,RED)),
220			salbedocolval(ambval,GRN)(1.-colval(ce,GRN)),
221			salbedocolval(ambval,BLU)(1.-colval(ce,BLU)));
222			addcolor(r->rcol, ca); /* ambient in scattering */
223			srcscatter(r); /* source in scattering */
224	greg	1.1	}
225
226
227			raytexture(r, mod) /* get material modifiers */
228			RAY *r;
229			int mod;
230			{
231			static int depth = 0;
232			register OBJREC *m;
233			/* check for infinite loop */
234			if (depth++ >= MAXLOOP)
235			objerror(r->ro, USER, "modifier loop");
236			/* execute textures and patterns */
237			for ( ; mod != OVOID; mod = m->omod) {
238			m = objptr(mod);
239	greg	2.9	/****** unnecessary test since modifier() is always called
240			if (!ismodifier(m->otype)) {
241	greg	1.1	sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
242			error(USER, errmsg);
243			}
244	greg	2.9	******/
245	greg	2.20	if ((*ofun[m->otype].funp)(m, r)) {
246			sprintf(errmsg, "conflicting material \"%s\"",
247			m->oname);
248			objerror(r->ro, USER, errmsg);
249			}
250	greg	1.1	}
251			depth--; /* end here */
252			}
253
254
255			raymixture(r, fore, back, coef) /* mix modifiers */
256			register RAY *r;
257			OBJECT fore, back;
258			double coef;
259			{
260	greg	2.9	RAY fr, br;
261			int foremat, backmat;
262	greg	1.1	register int i;
263			/* clip coefficient */
264			if (coef > 1.0)
265			coef = 1.0;
266			else if (coef < 0.0)
267			coef = 0.0;
268	greg	2.13	/* compute foreground and background */
269			foremat = backmat = -1;
270	greg	2.9	/* foreground */
271			copystruct(&fr, r);
272	greg	1.1	if (fore != OVOID && coef > FTINY)
273	greg	2.9	foremat = rayshade(&fr, fore);
274			/* background */
275			copystruct(&br, r);
276	greg	1.1	if (back != OVOID && coef < 1.0-FTINY)
277	greg	2.9	backmat = rayshade(&br, back);
278	greg	2.13	/* check */
279			if (foremat < 0)
280			if (backmat < 0)
281			foremat = backmat = 0;
282			else
283			foremat = backmat;
284			else if (backmat < 0)
285	greg	2.9	backmat = foremat;
286	greg	2.12	if ((foremat==0) != (backmat==0))
287	greg	2.10	objerror(r->ro, USER, "mixing material with non-material");
288	greg	2.12	/* mix perturbations */
289	greg	1.1	for (i = 0; i < 3; i++)
290	greg	2.12	r->pert[i] = coeffr.pert[i] + (1.0-coef)br.pert[i];
291			/* mix pattern colors */
292	greg	2.9	scalecolor(fr.pcol, coef);
293			scalecolor(br.pcol, 1.0-coef);
294	greg	2.12	copycolor(r->pcol, fr.pcol);
295			addcolor(r->pcol, br.pcol);
296			/* mix returned ray values */
297			if (foremat) {
298			scalecolor(fr.rcol, coef);
299			scalecolor(br.rcol, 1.0-coef);
300			copycolor(r->rcol, fr.rcol);
301			addcolor(r->rcol, br.rcol);
302	greg	2.10	r->rt = bright(fr.rcol) > bright(br.rcol) ? fr.rt : br.rt;
303	greg	2.12	}
304	greg	2.9	/* return value tells if material */
305			return(foremat);
306	greg	1.1	}
307
308
309			double
310	greg	2.21	raydist(r, flags) /* compute (cumulative) ray distance */
311			register RAY *r;
312			register int flags;
313			{
314			double sum = 0.0;
315
316			while (r != NULL && r->crtype&flags) {
317			sum += r->rot;
318			r = r->parent;
319			}
320			return(sum);
321			}
322
323
324			double
325	greg	1.1	raynormal(norm, r) /* compute perturbed normal for ray */
326			FVECT norm;
327			register RAY *r;
328			{
329			double newdot;
330			register int i;
331
332			/* The perturbation is added to the surface normal to obtain
333			* the new normal. If the new normal would affect the surface
334			* orientation wrt. the ray, a correction is made. The method is
335			* still fraught with problems since reflected rays and similar
336			* directions calculated from the surface normal may spawn rays behind
337			* the surface. The only solution is to curb textures at high
338	greg	1.9	* incidence (namely, keep DOT(rdir,pert) < Rdot).
339	greg	1.1	*/
340
341			for (i = 0; i < 3; i++)
342			norm[i] = r->ron[i] + r->pert[i];
343
344			if (normalize(norm) == 0.0) {
345			objerror(r->ro, WARNING, "illegal normal perturbation");
346			VCOPY(norm, r->ron);
347			return(r->rod);
348			}
349			newdot = -DOT(norm, r->rdir);
350			if ((newdot > 0.0) != (r->rod > 0.0)) { /* fix orientation */
351			for (i = 0; i < 3; i++)
352			norm[i] += 2.0newdotr->rdir[i];
353			newdot = -newdot;
354			}
355			return(newdot);
356	greg	1.12	}
357
358
359			newrayxf(r) /* get new tranformation matrix for ray */
360			RAY *r;
361			{
362			static struct xfn {
363			struct xfn *next;
364			FULLXF xf;
365			} xfseed = { &xfseed }, *xflast = &xfseed;
366			register struct xfn *xp;
367			register RAY *rp;
368
369			/*
370			* Search for transform in circular list that
371			* has no associated ray in the tree.
372			*/
373			xp = xflast;
374			for (rp = r->parent; rp != NULL; rp = rp->parent)
375			if (rp->rox == &xp->xf) { /* xp in use */
376			xp = xp->next; /* move to next */
377			if (xp == xflast) { /* need new one */
378	greg	1.14	xp = (struct xfn *)bmalloc(sizeof(struct xfn));
379	greg	1.12	if (xp == NULL)
380			error(SYSTEM,
381			"out of memory in newrayxf");
382			/* insert in list */
383			xp->next = xflast->next;
384			xflast->next = xp;
385			break; /* we're done */
386			}
387			rp = r; /* start check over */
388			}
389			/* got it */
390			r->rox = &xp->xf;
391			xflast = xp;
392	greg	1.1	}
393
394
395			flipsurface(r) /* reverse surface orientation */
396			register RAY *r;
397			{
398			r->rod = -r->rod;
399			r->ron[0] = -r->ron[0];
400			r->ron[1] = -r->ron[1];
401			r->ron[2] = -r->ron[2];
402			r->pert[0] = -r->pert[0];
403			r->pert[1] = -r->pert[1];
404			r->pert[2] = -r->pert[2];
405			}
406
407
408			localhit(r, scene) /* check for hit in the octree */
409			register RAY *r;
410			register CUBE *scene;
411			{
412	greg	2.3	OBJECT cxset[MAXCSET+1]; /* set of checked objects */
413	greg	1.1	FVECT curpos; /* current cube position */
414	greg	1.11	int sflags; /* sign flags */
415	greg	1.1	double t, dt;
416			register int i;
417
418	greg	1.21	nrays++; /* increment trace counter */
419	greg	1.11	sflags = 0;
420	greg	1.1	for (i = 0; i < 3; i++) {
421			curpos[i] = r->rorg[i];
422	greg	2.8	if (r->rdir[i] > 1e-7)
423	greg	1.11	sflags \|= 1 << i;
424	greg	2.8	else if (r->rdir[i] < -1e-7)
425	greg	1.11	sflags \|= 0x10 << i;
426	greg	1.1	}
427	greg	1.17	if (sflags == 0)
428			error(CONSISTENCY, "zero ray direction in localhit");
429	greg	2.17	/* start off assuming nothing hit */
430			if (r->rmax > FTINY) { /* except aft plane if one */
431			r->ro = &Aftplane;
432			r->rot = r->rmax;
433			for (i = 0; i < 3; i++)
434			r->rop[i] = r->rorg[i] + r->rot*r->rdir[i];
435			}
436			/* find global cube entrance point */
437	greg	1.1	t = 0.0;
438			if (!incube(scene, curpos)) {
439			/* find distance to entry */
440			for (i = 0; i < 3; i++) {
441			/* plane in our direction */
442	greg	1.11	if (sflags & 1<<i)
443	greg	1.1	dt = scene->cuorg[i];
444	greg	1.11	else if (sflags & 0x10<<i)
445	greg	1.1	dt = scene->cuorg[i] + scene->cusize;
446			else
447			continue;
448			/* distance to the plane */
449			dt = (dt - r->rorg[i])/r->rdir[i];
450			if (dt > t)
451			t = dt; /* farthest face is the one */
452			}
453			t += FTINY; /* fudge to get inside cube */
454	greg	2.17	if (t >= r->rot) /* clipped already */
455			return(0);
456	greg	1.1	/* advance position */
457			for (i = 0; i < 3; i++)
458			curpos[i] += r->rdir[i]*t;
459
460			if (!incube(scene, curpos)) /* non-intersecting ray */
461			return(0);
462			}
463	greg	2.3	cxset[0] = 0;
464	greg	2.19	raymove(curpos, cxset, sflags, r, scene);
465			return(r->ro != NULL & r->ro != &Aftplane);
466	greg	1.1	}
467
468
469			static int
470	greg	2.3	raymove(pos, cxs, dirf, r, cu) /* check for hit as we move */
471			FVECT pos; /* current position, modified herein */
472			OBJECT cxs; / checked objects, modified by checkhit */
473	greg	1.11	int dirf; /* direction indicators to speed tests */
474	greg	1.1	register RAY *r;
475			register CUBE *cu;
476			{
477			int ax;
478			double dt, t;
479
480			if (istree(cu->cutree)) { /* recurse on subcubes */
481			CUBE cukid;
482	greg	1.11	register int br, sgn;
483	greg	1.1
484			cukid.cusize = cu->cusize * 0.5; /* find subcube */
485			VCOPY(cukid.cuorg, cu->cuorg);
486			br = 0;
487			if (pos[0] >= cukid.cuorg[0]+cukid.cusize) {
488			cukid.cuorg[0] += cukid.cusize;
489			br \|= 1;
490			}
491			if (pos[1] >= cukid.cuorg[1]+cukid.cusize) {
492			cukid.cuorg[1] += cukid.cusize;
493			br \|= 2;
494			}
495			if (pos[2] >= cukid.cuorg[2]+cukid.cusize) {
496			cukid.cuorg[2] += cukid.cusize;
497			br \|= 4;
498			}
499			for ( ; ; ) {
500			cukid.cutree = octkid(cu->cutree, br);
501	greg	2.3	if ((ax = raymove(pos,cxs,dirf,r,&cukid)) == RAYHIT)
502	greg	1.1	return(RAYHIT);
503			sgn = 1 << ax;
504	greg	1.11	if (sgn & dirf) /* positive axis? */
505	greg	1.1	if (sgn & br)
506			return(ax); /* overflow */
507			else {
508			cukid.cuorg[ax] += cukid.cusize;
509			br \|= sgn;
510			}
511	greg	1.11	else
512			if (sgn & br) {
513			cukid.cuorg[ax] -= cukid.cusize;
514			br &= ~sgn;
515			} else
516			return(ax); /* underflow */
517	greg	1.1	}
518			/NOTREACHED/
519			}
520	greg	2.18	if (isfull(cu->cutree)) {
521			if (checkhit(r, cu, cxs))
522			return(RAYHIT);
523			} else if (r->ro == &Aftplane && incube(cu, r->rop))
524	greg	1.1	return(RAYHIT);
525			/* advance to next cube */
526	greg	1.11	if (dirf&0x11) {
527			dt = dirf&1 ? cu->cuorg[0] + cu->cusize : cu->cuorg[0];
528	greg	1.1	t = (dt - pos[0])/r->rdir[0];
529			ax = 0;
530			} else
531			t = FHUGE;
532	greg	1.11	if (dirf&0x22) {
533			dt = dirf&2 ? cu->cuorg[1] + cu->cusize : cu->cuorg[1];
534	greg	1.1	dt = (dt - pos[1])/r->rdir[1];
535			if (dt < t) {
536			t = dt;
537			ax = 1;
538			}
539			}
540	greg	1.11	if (dirf&0x44) {
541			dt = dirf&4 ? cu->cuorg[2] + cu->cusize : cu->cuorg[2];
542	greg	1.1	dt = (dt - pos[2])/r->rdir[2];
543			if (dt < t) {
544			t = dt;
545			ax = 2;
546			}
547			}
548			pos[0] += r->rdir[0]*t;
549			pos[1] += r->rdir[1]*t;
550			pos[2] += r->rdir[2]*t;
551			return(ax);
552			}
553
554
555			static
556	greg	2.3	checkhit(r, cu, cxs) /* check for hit in full cube */
557	greg	1.1	register RAY *r;
558			CUBE *cu;
559	greg	2.3	OBJECT *cxs;
560	greg	1.1	{
561			OBJECT oset[MAXSET+1];
562			register OBJREC *o;
563			register int i;
564
565			objset(oset, cu->cutree);
566	greg	2.3	checkset(oset, cxs); /* eliminate double-checking */
567	greg	1.1	for (i = oset[0]; i > 0; i--) {
568			o = objptr(oset[i]);
569			(*ofun[o->otype].funp)(o, r);
570			}
571			if (r->ro == NULL)
572			return(0); /* no scores yet */
573
574			return(incube(cu, r->rop)); /* hit OK if in current cube */
575	greg	2.2	}
576
577
578			static
579			checkset(os, cs) /* modify checked set and set to check */
580	greg	2.3	register OBJECT os; / os' = os - cs */
581			register OBJECT cs; / cs' = cs + os */
582	greg	2.2	{
583			OBJECT cset[MAXCSET+MAXSET+1];
584	greg	2.3	register int i, j;
585			int k;
586	greg	2.2	/* copy os in place, cset <- cs */
587			cset[0] = 0;
588			k = 0;
589			for (i = j = 1; i <= os[0]; i++) {
590			while (j <= cs[0] && cs[j] < os[i])
591			cset[++cset[0]] = cs[j++];
592			if (j > cs[0] \|\| os[i] != cs[j]) { /* object to check */
593			os[++k] = os[i];
594			cset[++cset[0]] = os[i];
595			}
596			}
597	greg	2.3	if (!(os[0] = k)) /* new "to check" set size */
598			return; /* special case */
599	greg	2.2	while (j <= cs[0]) /* get the rest of cs */
600			cset[++cset[0]] = cs[j++];
601	greg	2.3	if (cset[0] > MAXCSET) /* truncate "checked" set if nec. */
602	greg	2.2	cset[0] = MAXCSET;
603	greg	2.3	/* setcopy(cs, cset); / / copy cset back to cs */
604			os = cset;
605			for (i = os[0]; i-- >= 0; )
606			cs++ = os++;
607	greg	1.1	}