src/rt/raytrace.c

/* Copyright (c) 1998 Silicon Graphics, Inc. */

#ifndef lint
static char SCCSid[] = "$SunId$ SGI";
#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;
{
        double  re;

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


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->rt = r->rot = FHUGE;
        r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
        setcolor(r->pcol, 1.0, 1.0, 1.0);
        setcolor(r->rcol, 0.0, 0.0, 0.0);
}


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 && coef > FTINY)
                        raytrans(&fr);
                else if (foremat && coef < 1.0-FTINY)
                        raytrans(&br);
                                        /* mix perturbations */
        for (i = 0; i < 3; i++)
                r->pert[i] = coef*fr.pert[i] + (1.0-coef)*br.pert[i];
                                        /* mix pattern colors */
        scalecolor(fr.pcol, coef);
        scalecolor(br.pcol, 1.0-coef);
        copycolor(r->pcol, fr.pcol);
        addcolor(r->pcol, br.pcol);
                                        /* return value tells if material */
        if (!foremat & !backmat)
                return(0);
                                        /* mix returned ray values */
        scalecolor(fr.rcol, coef);
        scalecolor(br.rcol, 1.0-coef);
        copycolor(r->rcol, fr.rcol);
        addcolor(r->rcol, br.rcol);
        r->rt = bright(fr.rcol) > bright(br.rcol) ? fr.rt : br.rt;
        return(1);
}


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

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


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

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

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

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


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:	2.31
Committed:	Wed Jun 17 12:53:06 1998 UTC (25 years, 10 months ago) by gwlarson
Content type:	text/plain
Branch:	MAIN
Changes since 2.30:	+11 -3 lines
Log Message:	improved the way ray weights are computed for participating media
#	User	Rev	Content
1	gwlarson	2.31	/* Copyright (c) 1998 Silicon Graphics, Inc. */
2	greg	1.1
3			#ifndef lint
4	gwlarson	2.31	static char SCCSid[] = "$SunId$ SGI";
5	greg	1.1	#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	gwlarson	2.31	double re;
58
59	greg	1.1	if ((r->parent = ro) == NULL) { /* primary ray */
60			r->rlvl = 0;
61			r->rweight = rw;
62			r->crtype = r->rtype = rt;
63			r->rsrc = -1;
64			r->clipset = NULL;
65	greg	1.21	r->revf = raytrace;
66	greg	2.23	copycolor(r->cext, cextinction);
67	greg	2.26	copycolor(r->albedo, salbedo);
68	greg	2.23	r->gecc = seccg;
69			r->slights = NULL;
70	greg	1.1	} else { /* spawned ray */
71			r->rlvl = ro->rlvl;
72			if (rt & RAYREFL) {
73			r->rlvl++;
74			r->rsrc = -1;
75			r->clipset = ro->clipset;
76	greg	2.22	r->rmax = 0.0;
77	greg	1.1	} else {
78			r->rsrc = ro->rsrc;
79			r->clipset = ro->newcset;
80	greg	2.22	r->rmax = ro->rmax <= FTINY ? 0.0 : ro->rmax - ro->rot;
81	greg	1.1	}
82	greg	1.21	r->revf = ro->revf;
83	greg	2.23	copycolor(r->cext, ro->cext);
84	greg	2.26	copycolor(r->albedo, ro->albedo);
85	greg	2.23	r->gecc = ro->gecc;
86			r->slights = ro->slights;
87	greg	1.1	r->crtype = ro->crtype \| (r->rtype = rt);
88			VCOPY(r->rorg, ro->rop);
89	gwlarson	2.31	r->rweight = ro->rweight * rw;
90			/* estimate absorption */
91			re = colval(ro->cext,RED) < colval(ro->cext,GRN) ?
92			colval(ro->cext,RED) : colval(ro->cext,GRN);
93			if (colval(ro->cext,BLU) < re) re = colval(ro->cext,BLU);
94			if (re > 0.)
95			r->rweight = exp(-rero->rot);
96	greg	1.1	}
97	greg	1.22	rayclear(r);
98			return(r->rlvl <= maxdepth && r->rweight >= minweight ? 0 : -1);
99			}
100
101
102			rayclear(r) /* clear a ray for (re)evaluation */
103			register RAY *r;
104			{
105	greg	1.20	r->rno = raynum++;
106	greg	1.1	r->newcset = r->clipset;
107	greg	2.28	r->robj = OVOID;
108	greg	2.17	r->ro = NULL;
109	gregl	2.29	r->rt = r->rot = FHUGE;
110	greg	1.1	r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
111			setcolor(r->pcol, 1.0, 1.0, 1.0);
112			setcolor(r->rcol, 0.0, 0.0, 0.0);
113			}
114
115
116	greg	1.21	raytrace(r) /* trace a ray and compute its value */
117	greg	1.8	RAY *r;
118	greg	1.1	{
119			extern int (*trace)();
120
121	greg	1.15	if (localhit(r, &thescene))
122	greg	2.24	raycont(r); /* hit local surface, evaluate */
123	greg	2.16	else if (r->ro == &Aftplane) {
124	greg	2.23	r->ro = NULL; /* hit aft clipping plane */
125	greg	2.16	r->rot = FHUGE;
126			} else if (sourcehit(r))
127	greg	2.24	rayshade(r, r->ro->omod); /* distant source */
128	greg	1.1
129	greg	2.23	rayparticipate(r); /* for participating medium */
130
131	greg	1.1	if (trace != NULL)
132			(trace)(r); / trace execution */
133			}
134
135
136	greg	1.8	raycont(r) /* check for clipped object and continue */
137			register RAY *r;
138			{
139	greg	2.7	if ((r->clipset != NULL && inset(r->clipset, r->ro->omod)) \|\|
140	greg	2.24	!rayshade(r, r->ro->omod))
141	greg	1.8	raytrans(r);
142			}
143
144
145	greg	1.1	raytrans(r) /* transmit ray as is */
146	greg	1.8	register RAY *r;
147	greg	1.1	{
148			RAY tr;
149
150			if (rayorigin(&tr, r, TRANS, 1.0) == 0) {
151			VCOPY(tr.rdir, r->rdir);
152			rayvalue(&tr);
153			copycolor(r->rcol, tr.rcol);
154	greg	1.10	r->rt = r->rot + tr.rt;
155	greg	1.1	}
156			}
157
158
159			rayshade(r, mod) /* shade ray r with material mod */
160			register RAY *r;
161			int mod;
162			{
163			static int depth = 0;
164	greg	2.9	int gotmat;
165	greg	1.1	register OBJREC *m;
166			/* check for infinite loop */
167			if (depth++ >= MAXLOOP)
168	greg	1.4	objerror(r->ro, USER, "possible modifier loop");
169	greg	1.19	r->rt = r->rot; /* set effective ray length */
170	greg	2.9	for (gotmat = 0; !gotmat && mod != OVOID; mod = m->omod) {
171	greg	1.1	m = objptr(mod);
172	greg	1.4	/****** unnecessary test since modifier() is always called
173	greg	1.1	if (!ismodifier(m->otype)) {
174			sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
175			error(USER, errmsg);
176			}
177	greg	1.4	******/
178	greg	1.16	/* hack for irradiance calculation */
179			if (do_irrad && !(r->crtype & ~(PRIMARY\|TRANS))) {
180			if (irr_ignore(m->otype)) {
181			depth--;
182			raytrans(r);
183	greg	2.15	return(1);
184	greg	1.16	}
185	greg	1.18	if (!islight(m->otype))
186	greg	1.16	m = &Lamb;
187			}
188	greg	2.9	/* materials call raytexture */
189			gotmat = (*ofun[m->otype].funp)(m, r);
190	greg	1.1	}
191	greg	2.9	depth--;
192			return(gotmat);
193	greg	2.23	}
194
195
196			rayparticipate(r) /* compute ray medium participation */
197			register RAY *r;
198			{
199			COLOR ce, ca;
200			double re, ge, be;
201
202			if (intens(r->cext) <= 1./FHUGE)
203			return; /* no medium */
204	greg	2.27	re = r->rot*colval(r->cext,RED);
205			ge = r->rot*colval(r->cext,GRN);
206			be = r->rot*colval(r->cext,BLU);
207	greg	2.26	if (r->crtype & SHADOW) { /* no scattering for sources */
208			re *= 1. - colval(r->albedo,RED);
209			ge *= 1. - colval(r->albedo,GRN);
210			be *= 1. - colval(r->albedo,BLU);
211			}
212			setcolor(ce, re<=0. ? 1. : re>92. ? 0. : exp(-re),
213			ge<=0. ? 1. : ge>92. ? 0. : exp(-ge),
214			be<=0. ? 1. : be>92. ? 0. : exp(-be));
215	greg	2.23	multcolor(r->rcol, ce); /* path absorption */
216	greg	2.26	if (r->crtype & SHADOW \|\| intens(r->albedo) <= FTINY)
217	greg	2.23	return; /* no scattering */
218	greg	2.26	setcolor(ca,
219			colval(r->albedo,RED)colval(ambval,RED)(1.-colval(ce,RED)),
220			colval(r->albedo,GRN)colval(ambval,GRN)(1.-colval(ce,GRN)),
221			colval(r->albedo,BLU)colval(ambval,BLU)(1.-colval(ce,BLU)));
222	greg	2.23	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	greg	2.24	/* bound coefficient */
264	greg	1.1	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	greg	2.24	foremat = backmat = 0;
270	greg	2.9	/* foreground */
271			copystruct(&fr, r);
272	greg	2.24	if (coef > FTINY)
273	greg	2.9	foremat = rayshade(&fr, fore);
274			/* background */
275			copystruct(&br, r);
276	greg	2.24	if (coef < 1.0-FTINY)
277	greg	2.9	backmat = rayshade(&br, back);
278	greg	2.24	/* check for transparency */
279			if (backmat ^ foremat)
280	gwlarson	2.30	if (backmat && coef > FTINY)
281	greg	2.24	raytrans(&fr);
282	gwlarson	2.30	else if (foremat && coef < 1.0-FTINY)
283	greg	2.24	raytrans(&br);
284	greg	2.12	/* mix perturbations */
285	greg	1.1	for (i = 0; i < 3; i++)
286	greg	2.12	r->pert[i] = coeffr.pert[i] + (1.0-coef)br.pert[i];
287			/* mix pattern colors */
288	greg	2.9	scalecolor(fr.pcol, coef);
289			scalecolor(br.pcol, 1.0-coef);
290	greg	2.12	copycolor(r->pcol, fr.pcol);
291			addcolor(r->pcol, br.pcol);
292	greg	2.24	/* return value tells if material */
293			if (!foremat & !backmat)
294			return(0);
295	greg	2.12	/* mix returned ray values */
296	greg	2.24	scalecolor(fr.rcol, coef);
297			scalecolor(br.rcol, 1.0-coef);
298			copycolor(r->rcol, fr.rcol);
299			addcolor(r->rcol, br.rcol);
300			r->rt = bright(fr.rcol) > bright(br.rcol) ? fr.rt : br.rt;
301			return(1);
302	greg	1.1	}
303
304
305			double
306	greg	2.21	raydist(r, flags) /* compute (cumulative) ray distance */
307			register RAY *r;
308			register int flags;
309			{
310			double sum = 0.0;
311
312			while (r != NULL && r->crtype&flags) {
313			sum += r->rot;
314			r = r->parent;
315			}
316			return(sum);
317			}
318
319
320			double
321	greg	1.1	raynormal(norm, r) /* compute perturbed normal for ray */
322			FVECT norm;
323			register RAY *r;
324			{
325			double newdot;
326			register int i;
327
328			/* The perturbation is added to the surface normal to obtain
329			* the new normal. If the new normal would affect the surface
330			* orientation wrt. the ray, a correction is made. The method is
331			* still fraught with problems since reflected rays and similar
332			* directions calculated from the surface normal may spawn rays behind
333			* the surface. The only solution is to curb textures at high
334	greg	1.9	* incidence (namely, keep DOT(rdir,pert) < Rdot).
335	greg	1.1	*/
336
337			for (i = 0; i < 3; i++)
338			norm[i] = r->ron[i] + r->pert[i];
339
340			if (normalize(norm) == 0.0) {
341			objerror(r->ro, WARNING, "illegal normal perturbation");
342			VCOPY(norm, r->ron);
343			return(r->rod);
344			}
345			newdot = -DOT(norm, r->rdir);
346			if ((newdot > 0.0) != (r->rod > 0.0)) { /* fix orientation */
347			for (i = 0; i < 3; i++)
348			norm[i] += 2.0newdotr->rdir[i];
349			newdot = -newdot;
350			}
351			return(newdot);
352	greg	1.12	}
353
354
355			newrayxf(r) /* get new tranformation matrix for ray */
356			RAY *r;
357			{
358			static struct xfn {
359			struct xfn *next;
360			FULLXF xf;
361			} xfseed = { &xfseed }, *xflast = &xfseed;
362			register struct xfn *xp;
363			register RAY *rp;
364
365			/*
366			* Search for transform in circular list that
367			* has no associated ray in the tree.
368			*/
369			xp = xflast;
370			for (rp = r->parent; rp != NULL; rp = rp->parent)
371			if (rp->rox == &xp->xf) { /* xp in use */
372			xp = xp->next; /* move to next */
373			if (xp == xflast) { /* need new one */
374	greg	1.14	xp = (struct xfn *)bmalloc(sizeof(struct xfn));
375	greg	1.12	if (xp == NULL)
376			error(SYSTEM,
377			"out of memory in newrayxf");
378			/* insert in list */
379			xp->next = xflast->next;
380			xflast->next = xp;
381			break; /* we're done */
382			}
383			rp = r; /* start check over */
384			}
385			/* got it */
386			r->rox = &xp->xf;
387			xflast = xp;
388	greg	1.1	}
389
390
391			flipsurface(r) /* reverse surface orientation */
392			register RAY *r;
393			{
394			r->rod = -r->rod;
395			r->ron[0] = -r->ron[0];
396			r->ron[1] = -r->ron[1];
397			r->ron[2] = -r->ron[2];
398			r->pert[0] = -r->pert[0];
399			r->pert[1] = -r->pert[1];
400			r->pert[2] = -r->pert[2];
401			}
402
403
404			localhit(r, scene) /* check for hit in the octree */
405			register RAY *r;
406			register CUBE *scene;
407			{
408	greg	2.3	OBJECT cxset[MAXCSET+1]; /* set of checked objects */
409	greg	1.1	FVECT curpos; /* current cube position */
410	greg	1.11	int sflags; /* sign flags */
411	greg	1.1	double t, dt;
412			register int i;
413
414	greg	1.21	nrays++; /* increment trace counter */
415	greg	1.11	sflags = 0;
416	greg	1.1	for (i = 0; i < 3; i++) {
417			curpos[i] = r->rorg[i];
418	greg	2.8	if (r->rdir[i] > 1e-7)
419	greg	1.11	sflags \|= 1 << i;
420	greg	2.8	else if (r->rdir[i] < -1e-7)
421	greg	1.11	sflags \|= 0x10 << i;
422	greg	1.1	}
423	greg	1.17	if (sflags == 0)
424			error(CONSISTENCY, "zero ray direction in localhit");
425	greg	2.17	/* start off assuming nothing hit */
426			if (r->rmax > FTINY) { /* except aft plane if one */
427			r->ro = &Aftplane;
428			r->rot = r->rmax;
429			for (i = 0; i < 3; i++)
430			r->rop[i] = r->rorg[i] + r->rot*r->rdir[i];
431			}
432			/* find global cube entrance point */
433	greg	1.1	t = 0.0;
434			if (!incube(scene, curpos)) {
435			/* find distance to entry */
436			for (i = 0; i < 3; i++) {
437			/* plane in our direction */
438	greg	1.11	if (sflags & 1<<i)
439	greg	1.1	dt = scene->cuorg[i];
440	greg	1.11	else if (sflags & 0x10<<i)
441	greg	1.1	dt = scene->cuorg[i] + scene->cusize;
442			else
443			continue;
444			/* distance to the plane */
445			dt = (dt - r->rorg[i])/r->rdir[i];
446			if (dt > t)
447			t = dt; /* farthest face is the one */
448			}
449			t += FTINY; /* fudge to get inside cube */
450	greg	2.17	if (t >= r->rot) /* clipped already */
451			return(0);
452	greg	1.1	/* advance position */
453			for (i = 0; i < 3; i++)
454			curpos[i] += r->rdir[i]*t;
455
456			if (!incube(scene, curpos)) /* non-intersecting ray */
457			return(0);
458			}
459	greg	2.3	cxset[0] = 0;
460	greg	2.19	raymove(curpos, cxset, sflags, r, scene);
461			return(r->ro != NULL & r->ro != &Aftplane);
462	greg	1.1	}
463
464
465			static int
466	greg	2.3	raymove(pos, cxs, dirf, r, cu) /* check for hit as we move */
467			FVECT pos; /* current position, modified herein */
468			OBJECT cxs; / checked objects, modified by checkhit */
469	greg	1.11	int dirf; /* direction indicators to speed tests */
470	greg	1.1	register RAY *r;
471			register CUBE *cu;
472			{
473			int ax;
474			double dt, t;
475
476			if (istree(cu->cutree)) { /* recurse on subcubes */
477			CUBE cukid;
478	greg	1.11	register int br, sgn;
479	greg	1.1
480			cukid.cusize = cu->cusize * 0.5; /* find subcube */
481			VCOPY(cukid.cuorg, cu->cuorg);
482			br = 0;
483			if (pos[0] >= cukid.cuorg[0]+cukid.cusize) {
484			cukid.cuorg[0] += cukid.cusize;
485			br \|= 1;
486			}
487			if (pos[1] >= cukid.cuorg[1]+cukid.cusize) {
488			cukid.cuorg[1] += cukid.cusize;
489			br \|= 2;
490			}
491			if (pos[2] >= cukid.cuorg[2]+cukid.cusize) {
492			cukid.cuorg[2] += cukid.cusize;
493			br \|= 4;
494			}
495			for ( ; ; ) {
496			cukid.cutree = octkid(cu->cutree, br);
497	greg	2.3	if ((ax = raymove(pos,cxs,dirf,r,&cukid)) == RAYHIT)
498	greg	1.1	return(RAYHIT);
499			sgn = 1 << ax;
500	greg	1.11	if (sgn & dirf) /* positive axis? */
501	greg	1.1	if (sgn & br)
502			return(ax); /* overflow */
503			else {
504			cukid.cuorg[ax] += cukid.cusize;
505			br \|= sgn;
506			}
507	greg	1.11	else
508			if (sgn & br) {
509			cukid.cuorg[ax] -= cukid.cusize;
510			br &= ~sgn;
511			} else
512			return(ax); /* underflow */
513	greg	1.1	}
514			/NOTREACHED/
515			}
516	greg	2.18	if (isfull(cu->cutree)) {
517			if (checkhit(r, cu, cxs))
518			return(RAYHIT);
519			} else if (r->ro == &Aftplane && incube(cu, r->rop))
520	greg	1.1	return(RAYHIT);
521			/* advance to next cube */
522	greg	1.11	if (dirf&0x11) {
523			dt = dirf&1 ? cu->cuorg[0] + cu->cusize : cu->cuorg[0];
524	greg	1.1	t = (dt - pos[0])/r->rdir[0];
525			ax = 0;
526			} else
527			t = FHUGE;
528	greg	1.11	if (dirf&0x22) {
529			dt = dirf&2 ? cu->cuorg[1] + cu->cusize : cu->cuorg[1];
530	greg	1.1	dt = (dt - pos[1])/r->rdir[1];
531			if (dt < t) {
532			t = dt;
533			ax = 1;
534			}
535			}
536	greg	1.11	if (dirf&0x44) {
537			dt = dirf&4 ? cu->cuorg[2] + cu->cusize : cu->cuorg[2];
538	greg	1.1	dt = (dt - pos[2])/r->rdir[2];
539			if (dt < t) {
540			t = dt;
541			ax = 2;
542			}
543			}
544			pos[0] += r->rdir[0]*t;
545			pos[1] += r->rdir[1]*t;
546			pos[2] += r->rdir[2]*t;
547			return(ax);
548			}
549
550
551			static
552	greg	2.3	checkhit(r, cu, cxs) /* check for hit in full cube */
553	greg	1.1	register RAY *r;
554			CUBE *cu;
555	greg	2.3	OBJECT *cxs;
556	greg	1.1	{
557			OBJECT oset[MAXSET+1];
558			register OBJREC *o;
559			register int i;
560
561			objset(oset, cu->cutree);
562	greg	2.3	checkset(oset, cxs); /* eliminate double-checking */
563	greg	1.1	for (i = oset[0]; i > 0; i--) {
564			o = objptr(oset[i]);
565	greg	2.28	if ((*ofun[o->otype].funp)(o, r))
566			r->robj = oset[i];
567	greg	1.1	}
568			if (r->ro == NULL)
569			return(0); /* no scores yet */
570
571			return(incube(cu, r->rop)); /* hit OK if in current cube */
572	greg	2.2	}
573
574
575			static
576			checkset(os, cs) /* modify checked set and set to check */
577	greg	2.3	register OBJECT os; / os' = os - cs */
578			register OBJECT cs; / cs' = cs + os */
579	greg	2.2	{
580			OBJECT cset[MAXCSET+MAXSET+1];
581	greg	2.3	register int i, j;
582			int k;
583	greg	2.2	/* copy os in place, cset <- cs */
584			cset[0] = 0;
585			k = 0;
586			for (i = j = 1; i <= os[0]; i++) {
587			while (j <= cs[0] && cs[j] < os[i])
588			cset[++cset[0]] = cs[j++];
589			if (j > cs[0] \|\| os[i] != cs[j]) { /* object to check */
590			os[++k] = os[i];
591			cset[++cset[0]] = os[i];
592			}
593			}
594	greg	2.3	if (!(os[0] = k)) /* new "to check" set size */
595			return; /* special case */
596	greg	2.2	while (j <= cs[0]) /* get the rest of cs */
597			cset[++cset[0]] = cs[j++];
598	greg	2.3	if (cset[0] > MAXCSET) /* truncate "checked" set if nec. */
599	greg	2.2	cset[0] = MAXCSET;
600	greg	2.3	/* setcopy(cs, cset); / / copy cset back to cs */
601			os = cset;
602			for (i = os[0]; i-- >= 0; )
603			cs++ = os++;
604	greg	1.1	}