src/rt/raytrace.c

/* Copyright (c) 1991 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"

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

long  nrays = 0L;                       /* number of rays traced */

static double  Lambfa[5] = {PI, PI, PI, 0.0, 0.0};
OBJREC  Lamb = {
        OVOID, MAT_PLASTIC, "Lambertian",
        {0, 5, NULL, Lambfa}, NULL, -1,
};                                      /* a Lambertian surface */

#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;
        } else {                                /* spawned ray */
                r->rlvl = ro->rlvl;
                if (rt & RAYREFL) {
                        r->rlvl++;
                        r->rsrc = -1;
                        r->clipset = ro->clipset;
                } else {
                        r->rsrc = ro->rsrc;
                        r->clipset = ro->newcset;
                }
                r->rweight = ro->rweight * rw;
                r->crtype = ro->crtype | (r->rtype = rt);
                VCOPY(r->rorg, ro->rop);
        }
        r->rno = nrays;
        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;
        return(r->rlvl <= maxdepth && r->rweight >= minweight ? 0 : -1);
}


rayvalue(r)                     /* compute a ray's value */
RAY  *r;
{
        extern int  (*trace)();

        if (localhit(r, &thescene))
                raycont(r);
        else if (sourcehit(r))
                rayshade(r, r->ro->omod);

        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))
                raytrans(r);
        else
                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;
        register OBJREC  *m;
                                        /* check for infinite loop */
        if (depth++ >= MAXLOOP)
                objerror(r->ro, USER, "possible modifier loop");
        for ( ; mod != OVOID; mod = m->omod) {
                m = objptr(mod);
                /****** unnecessary test since modifier() is always called
                if (!ismodifier(m->otype)) {
                        sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
                        error(USER, errmsg);
                }
                ******/
                                        /* hack for irradiance calculation */
                if (do_irrad && !(r->crtype & ~(PRIMARY|TRANS))) {
                        if (irr_ignore(m->otype)) {
                                depth--;
                                raytrans(r);
                                return;
                        }
                        if (!islight(m->otype))
                                m = &Lamb;
                }
                (*ofun[m->otype].funp)(m, r);   /* execute function */
                m->lastrno = r->rno;
                if (ismaterial(m->otype)) {     /* materials call raytexture */
                        depth--;
                        return;         /* we're done */
                }
        }
        objerror(r->ro, USER, "material not found");
}


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);
                if (!istexture(m->otype)) {
                        sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
                        error(USER, errmsg);
                }
                (*ofun[m->otype].funp)(m, r);
                m->lastrno = r->rno;
        }
        depth--;                        /* end here */
}


raymixture(r, fore, back, coef)         /* mix modifiers */
register RAY  *r;
OBJECT  fore, back;
double  coef;
{
        FVECT  curpert, forepert, backpert;
        COLOR  curpcol, forepcol, backpcol;
        register int  i;
                                        /* clip coefficient */
        if (coef > 1.0)
                coef = 1.0;
        else if (coef < 0.0)
                coef = 0.0;
                                        /* save current mods */
        VCOPY(curpert, r->pert);
        copycolor(curpcol, r->pcol);
                                        /* compute new mods */
                                                /* foreground */
        r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
        setcolor(r->pcol, 1.0, 1.0, 1.0);
        if (fore != OVOID && coef > FTINY)
                raytexture(r, fore);
        VCOPY(forepert, r->pert);
        copycolor(forepcol, r->pcol);
                                                /* background */
        r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
        setcolor(r->pcol, 1.0, 1.0, 1.0);
        if (back != OVOID && coef < 1.0-FTINY)
                raytexture(r, back);
        VCOPY(backpert, r->pert);
        copycolor(backpcol, r->pcol);
                                        /* sum perturbations */
        for (i = 0; i < 3; i++)
                r->pert[i] = curpert[i] + coef*forepert[i] +
                                (1.0-coef)*backpert[i];
                                        /* multiply colors */
        setcolor(r->pcol, coef*colval(forepcol,RED) +
                                (1.0-coef)*colval(backpcol,RED),
                        coef*colval(forepcol,GRN) +
                                (1.0-coef)*colval(backpcol,GRN),
                        coef*colval(forepcol,BLU) +
                                (1.0-coef)*colval(backpcol,BLU));
        multcolor(r->pcol, curpcol);
}


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;
{
        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] > FTINY)
                        sflags |= 1 << i;
                else if (r->rdir[i] < -FTINY)
                        sflags |= 0x10 << i;
        }
        if (sflags == 0)
                error(CONSISTENCY, "zero ray direction in localhit");
        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 */
                                        /* advance position */
                for (i = 0; i < 3; i++)
                        curpos[i] += r->rdir[i]*t;

                if (!incube(scene, curpos))     /* non-intersecting ray */
                        return(0);
        }
        return(raymove(curpos, sflags, r, scene) == RAYHIT);
}


static int
raymove(pos, dirf, r, cu)               /* check for hit as we move */
FVECT  pos;                     /* modified */
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,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) && checkhit(r, cu))
                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)                 /* check for hit in full cube */
register RAY  *r;
CUBE  *cu;
{
        OBJECT  oset[MAXSET+1];
        register OBJREC  *o;
        register int  i;

        objset(oset, cu->cutree);
        for (i = oset[0]; i > 0; i--) {
                o = objptr(oset[i]);
                if (o->lastrno == r->rno)               /* checked already? */
                        continue;
                (*ofun[o->otype].funp)(o, r);
                o->lastrno = r->rno;
        }
        if (r->ro == NULL)
                return(0);                      /* no scores yet */

        return(incube(cu, r->rop));             /* hit OK if in current cube */
}
Revision:	1.18
Committed:	Wed May 29 11:09:23 1991 UTC (34 years, 5 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 1.17:	+1 -1 lines
Log Message:	fixed bug related to distant sources and -i option
#	User	Rev	Content
1	greg	1.17	/* Copyright (c) 1991 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	1.1	extern CUBE thescene; /* our scene */
22			extern int maxdepth; /* maximum recursion depth */
23			extern double minweight; /* minimum ray weight */
24	greg	1.15	extern int do_irrad; /* compute irradiance? */
25	greg	1.1
26			long nrays = 0L; /* number of rays traced */
27
28	greg	1.15	static double Lambfa[5] = {PI, PI, PI, 0.0, 0.0};
29			OBJREC Lamb = {
30			OVOID, MAT_PLASTIC, "Lambertian",
31			{0, 5, NULL, Lambfa}, NULL, -1,
32			}; /* a Lambertian surface */
33
34	greg	1.6	#define MAXLOOP 128 /* modifier loop detection */
35	greg	1.1
36			#define RAYHIT (-1) /* return value for intercepted ray */
37
38
39			rayorigin(r, ro, rt, rw) /* start new ray from old one */
40			register RAY r, ro;
41			int rt;
42			double rw;
43			{
44			if ((r->parent = ro) == NULL) { /* primary ray */
45			r->rlvl = 0;
46			r->rweight = rw;
47			r->crtype = r->rtype = rt;
48			r->rsrc = -1;
49			r->clipset = NULL;
50			} else { /* spawned ray */
51			r->rlvl = ro->rlvl;
52			if (rt & RAYREFL) {
53			r->rlvl++;
54			r->rsrc = -1;
55			r->clipset = ro->clipset;
56			} else {
57			r->rsrc = ro->rsrc;
58			r->clipset = ro->newcset;
59			}
60			r->rweight = ro->rweight * rw;
61			r->crtype = ro->crtype \| (r->rtype = rt);
62			VCOPY(r->rorg, ro->rop);
63			}
64			r->rno = nrays;
65			r->newcset = r->clipset;
66			r->ro = NULL;
67			r->rot = FHUGE;
68			r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
69			setcolor(r->pcol, 1.0, 1.0, 1.0);
70			setcolor(r->rcol, 0.0, 0.0, 0.0);
71	greg	1.10	r->rt = 0.0;
72	greg	1.1	return(r->rlvl <= maxdepth && r->rweight >= minweight ? 0 : -1);
73			}
74
75
76			rayvalue(r) /* compute a ray's value */
77	greg	1.8	RAY *r;
78	greg	1.1	{
79			extern int (*trace)();
80
81	greg	1.15	if (localhit(r, &thescene))
82	greg	1.8	raycont(r);
83	greg	1.15	else if (sourcehit(r))
84			rayshade(r, r->ro->omod);
85	greg	1.1
86			if (trace != NULL)
87			(trace)(r); / trace execution */
88			}
89
90
91	greg	1.8	raycont(r) /* check for clipped object and continue */
92			register RAY *r;
93			{
94			if (r->clipset != NULL && inset(r->clipset, r->ro->omod))
95			raytrans(r);
96			else
97			rayshade(r, r->ro->omod);
98			}
99
100
101	greg	1.1	raytrans(r) /* transmit ray as is */
102	greg	1.8	register RAY *r;
103	greg	1.1	{
104			RAY tr;
105
106			if (rayorigin(&tr, r, TRANS, 1.0) == 0) {
107			VCOPY(tr.rdir, r->rdir);
108			rayvalue(&tr);
109			copycolor(r->rcol, tr.rcol);
110	greg	1.10	r->rt = r->rot + tr.rt;
111	greg	1.1	}
112			}
113
114
115			rayshade(r, mod) /* shade ray r with material mod */
116			register RAY *r;
117			int mod;
118			{
119			static int depth = 0;
120			register OBJREC *m;
121			/* check for infinite loop */
122			if (depth++ >= MAXLOOP)
123	greg	1.4	objerror(r->ro, USER, "possible modifier loop");
124	greg	1.1	for ( ; mod != OVOID; mod = m->omod) {
125			m = objptr(mod);
126	greg	1.4	/****** unnecessary test since modifier() is always called
127	greg	1.1	if (!ismodifier(m->otype)) {
128			sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
129			error(USER, errmsg);
130			}
131	greg	1.4	******/
132	greg	1.16	/* hack for irradiance calculation */
133			if (do_irrad && !(r->crtype & ~(PRIMARY\|TRANS))) {
134			if (irr_ignore(m->otype)) {
135			depth--;
136			raytrans(r);
137			return;
138			}
139	greg	1.18	if (!islight(m->otype))
140	greg	1.16	m = &Lamb;
141			}
142	greg	1.1	(ofun[m->otype].funp)(m, r); / execute function */
143			m->lastrno = r->rno;
144			if (ismaterial(m->otype)) { /* materials call raytexture */
145			depth--;
146			return; /* we're done */
147			}
148			}
149			objerror(r->ro, USER, "material not found");
150			}
151
152
153			raytexture(r, mod) /* get material modifiers */
154			RAY *r;
155			int mod;
156			{
157			static int depth = 0;
158			register OBJREC *m;
159			/* check for infinite loop */
160			if (depth++ >= MAXLOOP)
161			objerror(r->ro, USER, "modifier loop");
162			/* execute textures and patterns */
163			for ( ; mod != OVOID; mod = m->omod) {
164			m = objptr(mod);
165			if (!istexture(m->otype)) {
166			sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
167			error(USER, errmsg);
168			}
169			(*ofun[m->otype].funp)(m, r);
170			m->lastrno = r->rno;
171			}
172			depth--; /* end here */
173			}
174
175
176			raymixture(r, fore, back, coef) /* mix modifiers */
177			register RAY *r;
178			OBJECT fore, back;
179			double coef;
180			{
181			FVECT curpert, forepert, backpert;
182			COLOR curpcol, forepcol, backpcol;
183			register int i;
184			/* clip coefficient */
185			if (coef > 1.0)
186			coef = 1.0;
187			else if (coef < 0.0)
188			coef = 0.0;
189			/* save current mods */
190			VCOPY(curpert, r->pert);
191			copycolor(curpcol, r->pcol);
192			/* compute new mods */
193			/* foreground */
194			r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
195			setcolor(r->pcol, 1.0, 1.0, 1.0);
196			if (fore != OVOID && coef > FTINY)
197			raytexture(r, fore);
198			VCOPY(forepert, r->pert);
199			copycolor(forepcol, r->pcol);
200			/* background */
201			r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
202			setcolor(r->pcol, 1.0, 1.0, 1.0);
203			if (back != OVOID && coef < 1.0-FTINY)
204			raytexture(r, back);
205			VCOPY(backpert, r->pert);
206			copycolor(backpcol, r->pcol);
207			/* sum perturbations */
208			for (i = 0; i < 3; i++)
209			r->pert[i] = curpert[i] + coef*forepert[i] +
210			(1.0-coef)*backpert[i];
211			/* multiply colors */
212			setcolor(r->pcol, coef*colval(forepcol,RED) +
213			(1.0-coef)*colval(backpcol,RED),
214			coef*colval(forepcol,GRN) +
215			(1.0-coef)*colval(backpcol,GRN),
216			coef*colval(forepcol,BLU) +
217			(1.0-coef)*colval(backpcol,BLU));
218			multcolor(r->pcol, curpcol);
219			}
220
221
222			double
223			raynormal(norm, r) /* compute perturbed normal for ray */
224			FVECT norm;
225			register RAY *r;
226			{
227			double newdot;
228			register int i;
229
230			/* The perturbation is added to the surface normal to obtain
231			* the new normal. If the new normal would affect the surface
232			* orientation wrt. the ray, a correction is made. The method is
233			* still fraught with problems since reflected rays and similar
234			* directions calculated from the surface normal may spawn rays behind
235			* the surface. The only solution is to curb textures at high
236	greg	1.9	* incidence (namely, keep DOT(rdir,pert) < Rdot).
237	greg	1.1	*/
238
239			for (i = 0; i < 3; i++)
240			norm[i] = r->ron[i] + r->pert[i];
241
242			if (normalize(norm) == 0.0) {
243			objerror(r->ro, WARNING, "illegal normal perturbation");
244			VCOPY(norm, r->ron);
245			return(r->rod);
246			}
247			newdot = -DOT(norm, r->rdir);
248			if ((newdot > 0.0) != (r->rod > 0.0)) { /* fix orientation */
249			for (i = 0; i < 3; i++)
250			norm[i] += 2.0newdotr->rdir[i];
251			newdot = -newdot;
252			}
253			return(newdot);
254	greg	1.12	}
255
256
257			newrayxf(r) /* get new tranformation matrix for ray */
258			RAY *r;
259			{
260			static struct xfn {
261			struct xfn *next;
262			FULLXF xf;
263			} xfseed = { &xfseed }, *xflast = &xfseed;
264			register struct xfn *xp;
265			register RAY *rp;
266
267			/*
268			* Search for transform in circular list that
269			* has no associated ray in the tree.
270			*/
271			xp = xflast;
272			for (rp = r->parent; rp != NULL; rp = rp->parent)
273			if (rp->rox == &xp->xf) { /* xp in use */
274			xp = xp->next; /* move to next */
275			if (xp == xflast) { /* need new one */
276	greg	1.14	xp = (struct xfn *)bmalloc(sizeof(struct xfn));
277	greg	1.12	if (xp == NULL)
278			error(SYSTEM,
279			"out of memory in newrayxf");
280			/* insert in list */
281			xp->next = xflast->next;
282			xflast->next = xp;
283			break; /* we're done */
284			}
285			rp = r; /* start check over */
286			}
287			/* got it */
288			r->rox = &xp->xf;
289			xflast = xp;
290	greg	1.1	}
291
292
293			flipsurface(r) /* reverse surface orientation */
294			register RAY *r;
295			{
296			r->rod = -r->rod;
297			r->ron[0] = -r->ron[0];
298			r->ron[1] = -r->ron[1];
299			r->ron[2] = -r->ron[2];
300			r->pert[0] = -r->pert[0];
301			r->pert[1] = -r->pert[1];
302			r->pert[2] = -r->pert[2];
303			}
304
305
306			localhit(r, scene) /* check for hit in the octree */
307			register RAY *r;
308			register CUBE *scene;
309			{
310			FVECT curpos; /* current cube position */
311	greg	1.11	int sflags; /* sign flags */
312	greg	1.1	double t, dt;
313			register int i;
314
315			nrays++; /* increment trace counter */
316
317	greg	1.11	sflags = 0;
318	greg	1.1	for (i = 0; i < 3; i++) {
319			curpos[i] = r->rorg[i];
320			if (r->rdir[i] > FTINY)
321	greg	1.11	sflags \|= 1 << i;
322	greg	1.1	else if (r->rdir[i] < -FTINY)
323	greg	1.11	sflags \|= 0x10 << i;
324	greg	1.1	}
325	greg	1.17	if (sflags == 0)
326			error(CONSISTENCY, "zero ray direction in localhit");
327	greg	1.1	t = 0.0;
328			if (!incube(scene, curpos)) {
329			/* find distance to entry */
330			for (i = 0; i < 3; i++) {
331			/* plane in our direction */
332	greg	1.11	if (sflags & 1<<i)
333	greg	1.1	dt = scene->cuorg[i];
334	greg	1.11	else if (sflags & 0x10<<i)
335	greg	1.1	dt = scene->cuorg[i] + scene->cusize;
336			else
337			continue;
338			/* distance to the plane */
339			dt = (dt - r->rorg[i])/r->rdir[i];
340			if (dt > t)
341			t = dt; /* farthest face is the one */
342			}
343			t += FTINY; /* fudge to get inside cube */
344			/* advance position */
345			for (i = 0; i < 3; i++)
346			curpos[i] += r->rdir[i]*t;
347
348			if (!incube(scene, curpos)) /* non-intersecting ray */
349			return(0);
350			}
351	greg	1.11	return(raymove(curpos, sflags, r, scene) == RAYHIT);
352	greg	1.1	}
353
354
355			static int
356	greg	1.11	raymove(pos, dirf, r, cu) /* check for hit as we move */
357	greg	1.1	FVECT pos; /* modified */
358	greg	1.11	int dirf; /* direction indicators to speed tests */
359	greg	1.1	register RAY *r;
360			register CUBE *cu;
361			{
362			int ax;
363			double dt, t;
364
365			if (istree(cu->cutree)) { /* recurse on subcubes */
366			CUBE cukid;
367	greg	1.11	register int br, sgn;
368	greg	1.1
369			cukid.cusize = cu->cusize * 0.5; /* find subcube */
370			VCOPY(cukid.cuorg, cu->cuorg);
371			br = 0;
372			if (pos[0] >= cukid.cuorg[0]+cukid.cusize) {
373			cukid.cuorg[0] += cukid.cusize;
374			br \|= 1;
375			}
376			if (pos[1] >= cukid.cuorg[1]+cukid.cusize) {
377			cukid.cuorg[1] += cukid.cusize;
378			br \|= 2;
379			}
380			if (pos[2] >= cukid.cuorg[2]+cukid.cusize) {
381			cukid.cuorg[2] += cukid.cusize;
382			br \|= 4;
383			}
384			for ( ; ; ) {
385			cukid.cutree = octkid(cu->cutree, br);
386	greg	1.11	if ((ax = raymove(pos,dirf,r,&cukid)) == RAYHIT)
387	greg	1.1	return(RAYHIT);
388			sgn = 1 << ax;
389	greg	1.11	if (sgn & dirf) /* positive axis? */
390	greg	1.1	if (sgn & br)
391			return(ax); /* overflow */
392			else {
393			cukid.cuorg[ax] += cukid.cusize;
394			br \|= sgn;
395			}
396	greg	1.11	else
397			if (sgn & br) {
398			cukid.cuorg[ax] -= cukid.cusize;
399			br &= ~sgn;
400			} else
401			return(ax); /* underflow */
402	greg	1.1	}
403			/NOTREACHED/
404			}
405			if (isfull(cu->cutree) && checkhit(r, cu))
406			return(RAYHIT);
407			/* advance to next cube */
408	greg	1.11	if (dirf&0x11) {
409			dt = dirf&1 ? cu->cuorg[0] + cu->cusize : cu->cuorg[0];
410	greg	1.1	t = (dt - pos[0])/r->rdir[0];
411			ax = 0;
412			} else
413			t = FHUGE;
414	greg	1.11	if (dirf&0x22) {
415			dt = dirf&2 ? cu->cuorg[1] + cu->cusize : cu->cuorg[1];
416	greg	1.1	dt = (dt - pos[1])/r->rdir[1];
417			if (dt < t) {
418			t = dt;
419			ax = 1;
420			}
421			}
422	greg	1.11	if (dirf&0x44) {
423			dt = dirf&4 ? cu->cuorg[2] + cu->cusize : cu->cuorg[2];
424	greg	1.1	dt = (dt - pos[2])/r->rdir[2];
425			if (dt < t) {
426			t = dt;
427			ax = 2;
428			}
429			}
430			pos[0] += r->rdir[0]*t;
431			pos[1] += r->rdir[1]*t;
432			pos[2] += r->rdir[2]*t;
433			return(ax);
434			}
435
436
437			static
438			checkhit(r, cu) /* check for hit in full cube */
439			register RAY *r;
440			CUBE *cu;
441			{
442			OBJECT oset[MAXSET+1];
443			register OBJREC *o;
444			register int i;
445
446			objset(oset, cu->cutree);
447			for (i = oset[0]; i > 0; i--) {
448			o = objptr(oset[i]);
449			if (o->lastrno == r->rno) /* checked already? */
450			continue;
451			(*ofun[o->otype].funp)(o, r);
452			o->lastrno = r->rno;
453			}
454			if (r->ro == NULL)
455			return(0); /* no scores yet */
456
457			return(incube(cu, r->rop)); /* hit OK if in current cube */
458			}