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();

#ifndef  MAXLOOP
#define  MAXLOOP        0               /* modifier loop detection */
#endif

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


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:	2.33
Committed:	Tue Sep 15 09:52:39 1998 UTC (25 years, 7 months ago) by gwlarson
Content type:	text/plain
Branch:	MAIN
Changes since 2.32:	+17 -5 lines
Log Message:	eliminated unecessary modifier loop checking (I hope!)
#	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	gwlarson	2.33	#ifndef MAXLOOP
48			#define MAXLOOP 0 /* modifier loop detection */
49			#endif
50	greg	1.1
51			#define RAYHIT (-1) /* return value for intercepted ray */
52
53
54			rayorigin(r, ro, rt, rw) /* start new ray from old one */
55			register RAY r, ro;
56			int rt;
57			double rw;
58			{
59	gwlarson	2.31	double re;
60
61	greg	1.1	if ((r->parent = ro) == NULL) { /* primary ray */
62			r->rlvl = 0;
63			r->rweight = rw;
64			r->crtype = r->rtype = rt;
65			r->rsrc = -1;
66			r->clipset = NULL;
67	greg	1.21	r->revf = raytrace;
68	greg	2.23	copycolor(r->cext, cextinction);
69	greg	2.26	copycolor(r->albedo, salbedo);
70	greg	2.23	r->gecc = seccg;
71			r->slights = NULL;
72	greg	1.1	} else { /* spawned ray */
73			r->rlvl = ro->rlvl;
74			if (rt & RAYREFL) {
75			r->rlvl++;
76			r->rsrc = -1;
77			r->clipset = ro->clipset;
78	greg	2.22	r->rmax = 0.0;
79	greg	1.1	} else {
80			r->rsrc = ro->rsrc;
81			r->clipset = ro->newcset;
82	greg	2.22	r->rmax = ro->rmax <= FTINY ? 0.0 : ro->rmax - ro->rot;
83	greg	1.1	}
84	greg	1.21	r->revf = ro->revf;
85	greg	2.23	copycolor(r->cext, ro->cext);
86	greg	2.26	copycolor(r->albedo, ro->albedo);
87	greg	2.23	r->gecc = ro->gecc;
88			r->slights = ro->slights;
89	greg	1.1	r->crtype = ro->crtype \| (r->rtype = rt);
90			VCOPY(r->rorg, ro->rop);
91	gwlarson	2.31	r->rweight = ro->rweight * rw;
92			/* estimate absorption */
93			re = colval(ro->cext,RED) < colval(ro->cext,GRN) ?
94			colval(ro->cext,RED) : colval(ro->cext,GRN);
95			if (colval(ro->cext,BLU) < re) re = colval(ro->cext,BLU);
96			if (re > 0.)
97			r->rweight = exp(-rero->rot);
98	greg	1.1	}
99	greg	1.22	rayclear(r);
100			return(r->rlvl <= maxdepth && r->rweight >= minweight ? 0 : -1);
101			}
102
103
104			rayclear(r) /* clear a ray for (re)evaluation */
105			register RAY *r;
106			{
107	greg	1.20	r->rno = raynum++;
108	greg	1.1	r->newcset = r->clipset;
109	greg	2.28	r->robj = OVOID;
110	greg	2.17	r->ro = NULL;
111	gregl	2.29	r->rt = r->rot = FHUGE;
112	greg	1.1	r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
113			setcolor(r->pcol, 1.0, 1.0, 1.0);
114			setcolor(r->rcol, 0.0, 0.0, 0.0);
115			}
116
117
118	greg	1.21	raytrace(r) /* trace a ray and compute its value */
119	greg	1.8	RAY *r;
120	greg	1.1	{
121			extern int (*trace)();
122
123	greg	1.15	if (localhit(r, &thescene))
124	greg	2.24	raycont(r); /* hit local surface, evaluate */
125	greg	2.16	else if (r->ro == &Aftplane) {
126	greg	2.23	r->ro = NULL; /* hit aft clipping plane */
127	greg	2.16	r->rot = FHUGE;
128			} else if (sourcehit(r))
129	greg	2.24	rayshade(r, r->ro->omod); /* distant source */
130	greg	1.1
131	greg	2.23	rayparticipate(r); /* for participating medium */
132
133	greg	1.1	if (trace != NULL)
134			(trace)(r); / trace execution */
135			}
136
137
138	greg	1.8	raycont(r) /* check for clipped object and continue */
139			register RAY *r;
140			{
141	greg	2.7	if ((r->clipset != NULL && inset(r->clipset, r->ro->omod)) \|\|
142	greg	2.24	!rayshade(r, r->ro->omod))
143	greg	1.8	raytrans(r);
144			}
145
146
147	greg	1.1	raytrans(r) /* transmit ray as is */
148	greg	1.8	register RAY *r;
149	greg	1.1	{
150			RAY tr;
151
152			if (rayorigin(&tr, r, TRANS, 1.0) == 0) {
153			VCOPY(tr.rdir, r->rdir);
154			rayvalue(&tr);
155			copycolor(r->rcol, tr.rcol);
156	greg	1.10	r->rt = r->rot + tr.rt;
157	greg	1.1	}
158			}
159
160
161			rayshade(r, mod) /* shade ray r with material mod */
162			register RAY *r;
163			int mod;
164			{
165	greg	2.9	int gotmat;
166	greg	1.1	register OBJREC *m;
167	gwlarson	2.33	#if MAXLOOP
168			static int depth = 0;
169	greg	1.1	/* check for infinite loop */
170			if (depth++ >= MAXLOOP)
171	greg	1.4	objerror(r->ro, USER, "possible modifier loop");
172	gwlarson	2.33	#endif
173	greg	1.19	r->rt = r->rot; /* set effective ray length */
174	greg	2.9	for (gotmat = 0; !gotmat && mod != OVOID; mod = m->omod) {
175	greg	1.1	m = objptr(mod);
176	greg	1.4	/****** unnecessary test since modifier() is always called
177	greg	1.1	if (!ismodifier(m->otype)) {
178			sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
179			error(USER, errmsg);
180			}
181	greg	1.4	******/
182	greg	1.16	/* hack for irradiance calculation */
183			if (do_irrad && !(r->crtype & ~(PRIMARY\|TRANS))) {
184			if (irr_ignore(m->otype)) {
185	gwlarson	2.33	#if MAXLOOP
186	greg	1.16	depth--;
187	gwlarson	2.33	#endif
188	greg	1.16	raytrans(r);
189	greg	2.15	return(1);
190	greg	1.16	}
191	greg	1.18	if (!islight(m->otype))
192	greg	1.16	m = &Lamb;
193			}
194	greg	2.9	/* materials call raytexture */
195			gotmat = (*ofun[m->otype].funp)(m, r);
196	greg	1.1	}
197	gwlarson	2.33	#if MAXLOOP
198	greg	2.9	depth--;
199	gwlarson	2.33	#endif
200	greg	2.9	return(gotmat);
201	greg	2.23	}
202
203
204			rayparticipate(r) /* compute ray medium participation */
205			register RAY *r;
206			{
207			COLOR ce, ca;
208			double re, ge, be;
209
210			if (intens(r->cext) <= 1./FHUGE)
211			return; /* no medium */
212	greg	2.27	re = r->rot*colval(r->cext,RED);
213			ge = r->rot*colval(r->cext,GRN);
214			be = r->rot*colval(r->cext,BLU);
215	greg	2.26	if (r->crtype & SHADOW) { /* no scattering for sources */
216			re *= 1. - colval(r->albedo,RED);
217			ge *= 1. - colval(r->albedo,GRN);
218			be *= 1. - colval(r->albedo,BLU);
219			}
220			setcolor(ce, re<=0. ? 1. : re>92. ? 0. : exp(-re),
221			ge<=0. ? 1. : ge>92. ? 0. : exp(-ge),
222			be<=0. ? 1. : be>92. ? 0. : exp(-be));
223	greg	2.23	multcolor(r->rcol, ce); /* path absorption */
224	greg	2.26	if (r->crtype & SHADOW \|\| intens(r->albedo) <= FTINY)
225	greg	2.23	return; /* no scattering */
226	greg	2.26	setcolor(ca,
227			colval(r->albedo,RED)colval(ambval,RED)(1.-colval(ce,RED)),
228			colval(r->albedo,GRN)colval(ambval,GRN)(1.-colval(ce,GRN)),
229			colval(r->albedo,BLU)colval(ambval,BLU)(1.-colval(ce,BLU)));
230	greg	2.23	addcolor(r->rcol, ca); /* ambient in scattering */
231			srcscatter(r); /* source in scattering */
232	greg	1.1	}
233
234
235			raytexture(r, mod) /* get material modifiers */
236			RAY *r;
237			int mod;
238			{
239	gwlarson	2.33	register OBJREC *m;
240			#if MAXLOOP
241	greg	1.1	static int depth = 0;
242			/* check for infinite loop */
243			if (depth++ >= MAXLOOP)
244			objerror(r->ro, USER, "modifier loop");
245	gwlarson	2.33	#endif
246	greg	1.1	/* execute textures and patterns */
247			for ( ; mod != OVOID; mod = m->omod) {
248			m = objptr(mod);
249	greg	2.9	/****** unnecessary test since modifier() is always called
250			if (!ismodifier(m->otype)) {
251	greg	1.1	sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
252			error(USER, errmsg);
253			}
254	greg	2.9	******/
255	greg	2.20	if ((*ofun[m->otype].funp)(m, r)) {
256			sprintf(errmsg, "conflicting material \"%s\"",
257			m->oname);
258			objerror(r->ro, USER, errmsg);
259			}
260	greg	1.1	}
261	gwlarson	2.33	#if MAXLOOP
262	greg	1.1	depth--; /* end here */
263	gwlarson	2.33	#endif
264	greg	1.1	}
265
266
267			raymixture(r, fore, back, coef) /* mix modifiers */
268			register RAY *r;
269			OBJECT fore, back;
270			double coef;
271			{
272	greg	2.9	RAY fr, br;
273			int foremat, backmat;
274	greg	1.1	register int i;
275	greg	2.24	/* bound coefficient */
276	greg	1.1	if (coef > 1.0)
277			coef = 1.0;
278			else if (coef < 0.0)
279			coef = 0.0;
280	greg	2.13	/* compute foreground and background */
281	greg	2.24	foremat = backmat = 0;
282	greg	2.9	/* foreground */
283			copystruct(&fr, r);
284	greg	2.24	if (coef > FTINY)
285	greg	2.9	foremat = rayshade(&fr, fore);
286			/* background */
287			copystruct(&br, r);
288	greg	2.24	if (coef < 1.0-FTINY)
289	greg	2.9	backmat = rayshade(&br, back);
290	greg	2.24	/* check for transparency */
291			if (backmat ^ foremat)
292	gwlarson	2.33	if (backmat && coef > FTINY)
293	greg	2.24	raytrans(&fr);
294	gwlarson	2.33	else if (foremat && coef < 1.0-FTINY)
295	greg	2.24	raytrans(&br);
296	greg	2.12	/* mix perturbations */
297	greg	1.1	for (i = 0; i < 3; i++)
298	greg	2.12	r->pert[i] = coeffr.pert[i] + (1.0-coef)br.pert[i];
299			/* mix pattern colors */
300	greg	2.9	scalecolor(fr.pcol, coef);
301			scalecolor(br.pcol, 1.0-coef);
302	greg	2.12	copycolor(r->pcol, fr.pcol);
303			addcolor(r->pcol, br.pcol);
304	greg	2.24	/* return value tells if material */
305			if (!foremat & !backmat)
306			return(0);
307	greg	2.12	/* mix returned ray values */
308	greg	2.24	scalecolor(fr.rcol, coef);
309			scalecolor(br.rcol, 1.0-coef);
310			copycolor(r->rcol, fr.rcol);
311			addcolor(r->rcol, br.rcol);
312			r->rt = bright(fr.rcol) > bright(br.rcol) ? fr.rt : br.rt;
313			return(1);
314	greg	1.1	}
315
316
317			double
318	greg	2.21	raydist(r, flags) /* compute (cumulative) ray distance */
319			register RAY *r;
320			register int flags;
321			{
322			double sum = 0.0;
323
324			while (r != NULL && r->crtype&flags) {
325			sum += r->rot;
326			r = r->parent;
327			}
328			return(sum);
329			}
330
331
332			double
333	greg	1.1	raynormal(norm, r) /* compute perturbed normal for ray */
334			FVECT norm;
335			register RAY *r;
336			{
337			double newdot;
338			register int i;
339
340			/* The perturbation is added to the surface normal to obtain
341			* the new normal. If the new normal would affect the surface
342			* orientation wrt. the ray, a correction is made. The method is
343			* still fraught with problems since reflected rays and similar
344			* directions calculated from the surface normal may spawn rays behind
345			* the surface. The only solution is to curb textures at high
346	greg	1.9	* incidence (namely, keep DOT(rdir,pert) < Rdot).
347	greg	1.1	*/
348
349			for (i = 0; i < 3; i++)
350			norm[i] = r->ron[i] + r->pert[i];
351
352			if (normalize(norm) == 0.0) {
353			objerror(r->ro, WARNING, "illegal normal perturbation");
354			VCOPY(norm, r->ron);
355			return(r->rod);
356			}
357			newdot = -DOT(norm, r->rdir);
358			if ((newdot > 0.0) != (r->rod > 0.0)) { /* fix orientation */
359			for (i = 0; i < 3; i++)
360			norm[i] += 2.0newdotr->rdir[i];
361			newdot = -newdot;
362			}
363			return(newdot);
364	greg	1.12	}
365
366
367			newrayxf(r) /* get new tranformation matrix for ray */
368			RAY *r;
369			{
370			static struct xfn {
371			struct xfn *next;
372			FULLXF xf;
373			} xfseed = { &xfseed }, *xflast = &xfseed;
374			register struct xfn *xp;
375			register RAY *rp;
376
377			/*
378			* Search for transform in circular list that
379			* has no associated ray in the tree.
380			*/
381			xp = xflast;
382			for (rp = r->parent; rp != NULL; rp = rp->parent)
383			if (rp->rox == &xp->xf) { /* xp in use */
384			xp = xp->next; /* move to next */
385			if (xp == xflast) { /* need new one */
386	greg	1.14	xp = (struct xfn *)bmalloc(sizeof(struct xfn));
387	greg	1.12	if (xp == NULL)
388			error(SYSTEM,
389			"out of memory in newrayxf");
390			/* insert in list */
391			xp->next = xflast->next;
392			xflast->next = xp;
393			break; /* we're done */
394			}
395			rp = r; /* start check over */
396			}
397			/* got it */
398			r->rox = &xp->xf;
399			xflast = xp;
400	greg	1.1	}
401
402
403			flipsurface(r) /* reverse surface orientation */
404			register RAY *r;
405			{
406			r->rod = -r->rod;
407			r->ron[0] = -r->ron[0];
408			r->ron[1] = -r->ron[1];
409			r->ron[2] = -r->ron[2];
410			r->pert[0] = -r->pert[0];
411			r->pert[1] = -r->pert[1];
412			r->pert[2] = -r->pert[2];
413			}
414
415
416			localhit(r, scene) /* check for hit in the octree */
417			register RAY *r;
418			register CUBE *scene;
419			{
420	greg	2.3	OBJECT cxset[MAXCSET+1]; /* set of checked objects */
421	greg	1.1	FVECT curpos; /* current cube position */
422	greg	1.11	int sflags; /* sign flags */
423	greg	1.1	double t, dt;
424			register int i;
425
426	greg	1.21	nrays++; /* increment trace counter */
427	greg	1.11	sflags = 0;
428	greg	1.1	for (i = 0; i < 3; i++) {
429			curpos[i] = r->rorg[i];
430	greg	2.8	if (r->rdir[i] > 1e-7)
431	greg	1.11	sflags \|= 1 << i;
432	greg	2.8	else if (r->rdir[i] < -1e-7)
433	greg	1.11	sflags \|= 0x10 << i;
434	greg	1.1	}
435	greg	1.17	if (sflags == 0)
436			error(CONSISTENCY, "zero ray direction in localhit");
437	greg	2.17	/* start off assuming nothing hit */
438			if (r->rmax > FTINY) { /* except aft plane if one */
439			r->ro = &Aftplane;
440			r->rot = r->rmax;
441			for (i = 0; i < 3; i++)
442			r->rop[i] = r->rorg[i] + r->rot*r->rdir[i];
443			}
444			/* find global cube entrance point */
445	greg	1.1	t = 0.0;
446			if (!incube(scene, curpos)) {
447			/* find distance to entry */
448			for (i = 0; i < 3; i++) {
449			/* plane in our direction */
450	greg	1.11	if (sflags & 1<<i)
451	greg	1.1	dt = scene->cuorg[i];
452	greg	1.11	else if (sflags & 0x10<<i)
453	greg	1.1	dt = scene->cuorg[i] + scene->cusize;
454			else
455			continue;
456			/* distance to the plane */
457			dt = (dt - r->rorg[i])/r->rdir[i];
458			if (dt > t)
459			t = dt; /* farthest face is the one */
460			}
461			t += FTINY; /* fudge to get inside cube */
462	greg	2.17	if (t >= r->rot) /* clipped already */
463			return(0);
464	greg	1.1	/* advance position */
465			for (i = 0; i < 3; i++)
466			curpos[i] += r->rdir[i]*t;
467
468			if (!incube(scene, curpos)) /* non-intersecting ray */
469			return(0);
470			}
471	greg	2.3	cxset[0] = 0;
472	greg	2.19	raymove(curpos, cxset, sflags, r, scene);
473			return(r->ro != NULL & r->ro != &Aftplane);
474	greg	1.1	}
475
476
477			static int
478	greg	2.3	raymove(pos, cxs, dirf, r, cu) /* check for hit as we move */
479			FVECT pos; /* current position, modified herein */
480			OBJECT cxs; / checked objects, modified by checkhit */
481	greg	1.11	int dirf; /* direction indicators to speed tests */
482	greg	1.1	register RAY *r;
483			register CUBE *cu;
484			{
485			int ax;
486			double dt, t;
487
488			if (istree(cu->cutree)) { /* recurse on subcubes */
489			CUBE cukid;
490	greg	1.11	register int br, sgn;
491	greg	1.1
492			cukid.cusize = cu->cusize * 0.5; /* find subcube */
493			VCOPY(cukid.cuorg, cu->cuorg);
494			br = 0;
495			if (pos[0] >= cukid.cuorg[0]+cukid.cusize) {
496			cukid.cuorg[0] += cukid.cusize;
497			br \|= 1;
498			}
499			if (pos[1] >= cukid.cuorg[1]+cukid.cusize) {
500			cukid.cuorg[1] += cukid.cusize;
501			br \|= 2;
502			}
503			if (pos[2] >= cukid.cuorg[2]+cukid.cusize) {
504			cukid.cuorg[2] += cukid.cusize;
505			br \|= 4;
506			}
507			for ( ; ; ) {
508			cukid.cutree = octkid(cu->cutree, br);
509	greg	2.3	if ((ax = raymove(pos,cxs,dirf,r,&cukid)) == RAYHIT)
510	greg	1.1	return(RAYHIT);
511			sgn = 1 << ax;
512	greg	1.11	if (sgn & dirf) /* positive axis? */
513	greg	1.1	if (sgn & br)
514			return(ax); /* overflow */
515			else {
516			cukid.cuorg[ax] += cukid.cusize;
517			br \|= sgn;
518			}
519	greg	1.11	else
520			if (sgn & br) {
521			cukid.cuorg[ax] -= cukid.cusize;
522			br &= ~sgn;
523			} else
524			return(ax); /* underflow */
525	greg	1.1	}
526			/NOTREACHED/
527			}
528	greg	2.18	if (isfull(cu->cutree)) {
529			if (checkhit(r, cu, cxs))
530			return(RAYHIT);
531			} else if (r->ro == &Aftplane && incube(cu, r->rop))
532	greg	1.1	return(RAYHIT);
533			/* advance to next cube */
534	greg	1.11	if (dirf&0x11) {
535			dt = dirf&1 ? cu->cuorg[0] + cu->cusize : cu->cuorg[0];
536	greg	1.1	t = (dt - pos[0])/r->rdir[0];
537			ax = 0;
538			} else
539			t = FHUGE;
540	greg	1.11	if (dirf&0x22) {
541			dt = dirf&2 ? cu->cuorg[1] + cu->cusize : cu->cuorg[1];
542	greg	1.1	dt = (dt - pos[1])/r->rdir[1];
543			if (dt < t) {
544			t = dt;
545			ax = 1;
546			}
547			}
548	greg	1.11	if (dirf&0x44) {
549			dt = dirf&4 ? cu->cuorg[2] + cu->cusize : cu->cuorg[2];
550	greg	1.1	dt = (dt - pos[2])/r->rdir[2];
551			if (dt < t) {
552			t = dt;
553			ax = 2;
554			}
555			}
556			pos[0] += r->rdir[0]*t;
557			pos[1] += r->rdir[1]*t;
558			pos[2] += r->rdir[2]*t;
559			return(ax);
560			}
561
562
563			static
564	greg	2.3	checkhit(r, cu, cxs) /* check for hit in full cube */
565	greg	1.1	register RAY *r;
566			CUBE *cu;
567	greg	2.3	OBJECT *cxs;
568	greg	1.1	{
569			OBJECT oset[MAXSET+1];
570			register OBJREC *o;
571			register int i;
572
573			objset(oset, cu->cutree);
574	greg	2.3	checkset(oset, cxs); /* eliminate double-checking */
575	greg	1.1	for (i = oset[0]; i > 0; i--) {
576			o = objptr(oset[i]);
577	greg	2.28	if ((*ofun[o->otype].funp)(o, r))
578			r->robj = oset[i];
579	greg	1.1	}
580			if (r->ro == NULL)
581			return(0); /* no scores yet */
582
583			return(incube(cu, r->rop)); /* hit OK if in current cube */
584	greg	2.2	}
585
586
587			static
588			checkset(os, cs) /* modify checked set and set to check */
589	greg	2.3	register OBJECT os; / os' = os - cs */
590			register OBJECT cs; / cs' = cs + os */
591	greg	2.2	{
592			OBJECT cset[MAXCSET+MAXSET+1];
593	greg	2.3	register int i, j;
594			int k;
595	greg	2.2	/* copy os in place, cset <- cs */
596			cset[0] = 0;
597			k = 0;
598			for (i = j = 1; i <= os[0]; i++) {
599			while (j <= cs[0] && cs[j] < os[i])
600			cset[++cset[0]] = cs[j++];
601			if (j > cs[0] \|\| os[i] != cs[j]) { /* object to check */
602			os[++k] = os[i];
603			cset[++cset[0]] = os[i];
604			}
605			}
606	greg	2.3	if (!(os[0] = k)) /* new "to check" set size */
607			return; /* special case */
608	greg	2.2	while (j <= cs[0]) /* get the rest of cs */
609			cset[++cset[0]] = cs[j++];
610	greg	2.3	if (cset[0] > MAXCSET) /* truncate "checked" set if nec. */
611	greg	2.2	cset[0] = MAXCSET;
612	greg	2.3	/* setcopy(cs, cset); / / copy cset back to cs */
613			os = cset;
614			for (i = os[0]; i-- >= 0; )
615			cs++ = os++;
616	greg	1.1	}