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  raynum = 0L;                      /* next unique ray number */
long  nrays = 0L;                       /* number of calls to localhit */

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;
                r->revf = raytrace;
        } 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->revf = ro->revf;
                r->rweight = ro->rweight * rw;
                r->crtype = ro->crtype | (r->rtype = rt);
                VCOPY(r->rorg, ro->rop);
        }
        r->rno = raynum++;
        r->newcset = r->clipset;
        r->ro = NULL;
        r->rot = FHUGE;
        r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
        setcolor(r->pcol, 1.0, 1.0, 1.0);
        setcolor(r->rcol, 0.0, 0.0, 0.0);
        r->rt = 0.0;
        return(r->rlvl <= maxdepth && r->rweight >= minweight ? 0 : -1);
}


raytrace(r)                     /* trace a ray and compute its 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");
        r->rt = r->rot;                 /* set effective ray length */
        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:	1.21
Committed:	Thu Jun 20 13:29:32 1991 UTC (32 years, 10 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 1.20:	+5 -3 lines
Log Message:	added revf member to ray structure for dynamic evaluation
#	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	greg	1.20	long raynum = 0L; /* next unique ray number */
27	greg	1.21	long nrays = 0L; /* number of calls to localhit */
28	greg	1.1
29	greg	1.15	static double Lambfa[5] = {PI, PI, PI, 0.0, 0.0};
30			OBJREC Lamb = {
31			OVOID, MAT_PLASTIC, "Lambertian",
32			{0, 5, NULL, Lambfa}, NULL, -1,
33			}; /* a Lambertian surface */
34
35	greg	1.6	#define MAXLOOP 128 /* modifier loop detection */
36	greg	1.1
37			#define RAYHIT (-1) /* return value for intercepted ray */
38
39
40			rayorigin(r, ro, rt, rw) /* start new ray from old one */
41			register RAY r, ro;
42			int rt;
43			double rw;
44			{
45			if ((r->parent = ro) == NULL) { /* primary ray */
46			r->rlvl = 0;
47			r->rweight = rw;
48			r->crtype = r->rtype = rt;
49			r->rsrc = -1;
50			r->clipset = NULL;
51	greg	1.21	r->revf = raytrace;
52	greg	1.1	} else { /* spawned ray */
53			r->rlvl = ro->rlvl;
54			if (rt & RAYREFL) {
55			r->rlvl++;
56			r->rsrc = -1;
57			r->clipset = ro->clipset;
58			} else {
59			r->rsrc = ro->rsrc;
60			r->clipset = ro->newcset;
61			}
62	greg	1.21	r->revf = ro->revf;
63	greg	1.1	r->rweight = ro->rweight * rw;
64			r->crtype = ro->crtype \| (r->rtype = rt);
65			VCOPY(r->rorg, ro->rop);
66			}
67	greg	1.20	r->rno = raynum++;
68	greg	1.1	r->newcset = r->clipset;
69			r->ro = NULL;
70			r->rot = FHUGE;
71			r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
72			setcolor(r->pcol, 1.0, 1.0, 1.0);
73			setcolor(r->rcol, 0.0, 0.0, 0.0);
74	greg	1.10	r->rt = 0.0;
75	greg	1.1	return(r->rlvl <= maxdepth && r->rweight >= minweight ? 0 : -1);
76			}
77
78
79	greg	1.21	raytrace(r) /* trace a ray and compute its value */
80	greg	1.8	RAY *r;
81	greg	1.1	{
82			extern int (*trace)();
83
84	greg	1.15	if (localhit(r, &thescene))
85	greg	1.8	raycont(r);
86	greg	1.15	else if (sourcehit(r))
87			rayshade(r, r->ro->omod);
88	greg	1.1
89			if (trace != NULL)
90			(trace)(r); / trace execution */
91			}
92
93
94	greg	1.8	raycont(r) /* check for clipped object and continue */
95			register RAY *r;
96			{
97			if (r->clipset != NULL && inset(r->clipset, r->ro->omod))
98			raytrans(r);
99			else
100			rayshade(r, r->ro->omod);
101			}
102
103
104	greg	1.1	raytrans(r) /* transmit ray as is */
105	greg	1.8	register RAY *r;
106	greg	1.1	{
107			RAY tr;
108
109			if (rayorigin(&tr, r, TRANS, 1.0) == 0) {
110			VCOPY(tr.rdir, r->rdir);
111			rayvalue(&tr);
112			copycolor(r->rcol, tr.rcol);
113	greg	1.10	r->rt = r->rot + tr.rt;
114	greg	1.1	}
115			}
116
117
118			rayshade(r, mod) /* shade ray r with material mod */
119			register RAY *r;
120			int mod;
121			{
122			static int depth = 0;
123			register OBJREC *m;
124			/* check for infinite loop */
125			if (depth++ >= MAXLOOP)
126	greg	1.4	objerror(r->ro, USER, "possible modifier loop");
127	greg	1.19	r->rt = r->rot; /* set effective ray length */
128	greg	1.1	for ( ; mod != OVOID; mod = m->omod) {
129			m = objptr(mod);
130	greg	1.4	/****** unnecessary test since modifier() is always called
131	greg	1.1	if (!ismodifier(m->otype)) {
132			sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
133			error(USER, errmsg);
134			}
135	greg	1.4	******/
136	greg	1.16	/* hack for irradiance calculation */
137			if (do_irrad && !(r->crtype & ~(PRIMARY\|TRANS))) {
138			if (irr_ignore(m->otype)) {
139			depth--;
140			raytrans(r);
141			return;
142			}
143	greg	1.18	if (!islight(m->otype))
144	greg	1.16	m = &Lamb;
145			}
146	greg	1.1	(ofun[m->otype].funp)(m, r); / execute function */
147			m->lastrno = r->rno;
148			if (ismaterial(m->otype)) { /* materials call raytexture */
149			depth--;
150			return; /* we're done */
151			}
152			}
153			objerror(r->ro, USER, "material not found");
154			}
155
156
157			raytexture(r, mod) /* get material modifiers */
158			RAY *r;
159			int mod;
160			{
161			static int depth = 0;
162			register OBJREC *m;
163			/* check for infinite loop */
164			if (depth++ >= MAXLOOP)
165			objerror(r->ro, USER, "modifier loop");
166			/* execute textures and patterns */
167			for ( ; mod != OVOID; mod = m->omod) {
168			m = objptr(mod);
169			if (!istexture(m->otype)) {
170			sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
171			error(USER, errmsg);
172			}
173			(*ofun[m->otype].funp)(m, r);
174			m->lastrno = r->rno;
175			}
176			depth--; /* end here */
177			}
178
179
180			raymixture(r, fore, back, coef) /* mix modifiers */
181			register RAY *r;
182			OBJECT fore, back;
183			double coef;
184			{
185			FVECT curpert, forepert, backpert;
186			COLOR curpcol, forepcol, backpcol;
187			register int i;
188			/* clip coefficient */
189			if (coef > 1.0)
190			coef = 1.0;
191			else if (coef < 0.0)
192			coef = 0.0;
193			/* save current mods */
194			VCOPY(curpert, r->pert);
195			copycolor(curpcol, r->pcol);
196			/* compute new mods */
197			/* foreground */
198			r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
199			setcolor(r->pcol, 1.0, 1.0, 1.0);
200			if (fore != OVOID && coef > FTINY)
201			raytexture(r, fore);
202			VCOPY(forepert, r->pert);
203			copycolor(forepcol, r->pcol);
204			/* background */
205			r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
206			setcolor(r->pcol, 1.0, 1.0, 1.0);
207			if (back != OVOID && coef < 1.0-FTINY)
208			raytexture(r, back);
209			VCOPY(backpert, r->pert);
210			copycolor(backpcol, r->pcol);
211			/* sum perturbations */
212			for (i = 0; i < 3; i++)
213			r->pert[i] = curpert[i] + coef*forepert[i] +
214			(1.0-coef)*backpert[i];
215			/* multiply colors */
216			setcolor(r->pcol, coef*colval(forepcol,RED) +
217			(1.0-coef)*colval(backpcol,RED),
218			coef*colval(forepcol,GRN) +
219			(1.0-coef)*colval(backpcol,GRN),
220			coef*colval(forepcol,BLU) +
221			(1.0-coef)*colval(backpcol,BLU));
222			multcolor(r->pcol, curpcol);
223			}
224
225
226			double
227			raynormal(norm, r) /* compute perturbed normal for ray */
228			FVECT norm;
229			register RAY *r;
230			{
231			double newdot;
232			register int i;
233
234			/* The perturbation is added to the surface normal to obtain
235			* the new normal. If the new normal would affect the surface
236			* orientation wrt. the ray, a correction is made. The method is
237			* still fraught with problems since reflected rays and similar
238			* directions calculated from the surface normal may spawn rays behind
239			* the surface. The only solution is to curb textures at high
240	greg	1.9	* incidence (namely, keep DOT(rdir,pert) < Rdot).
241	greg	1.1	*/
242
243			for (i = 0; i < 3; i++)
244			norm[i] = r->ron[i] + r->pert[i];
245
246			if (normalize(norm) == 0.0) {
247			objerror(r->ro, WARNING, "illegal normal perturbation");
248			VCOPY(norm, r->ron);
249			return(r->rod);
250			}
251			newdot = -DOT(norm, r->rdir);
252			if ((newdot > 0.0) != (r->rod > 0.0)) { /* fix orientation */
253			for (i = 0; i < 3; i++)
254			norm[i] += 2.0newdotr->rdir[i];
255			newdot = -newdot;
256			}
257			return(newdot);
258	greg	1.12	}
259
260
261			newrayxf(r) /* get new tranformation matrix for ray */
262			RAY *r;
263			{
264			static struct xfn {
265			struct xfn *next;
266			FULLXF xf;
267			} xfseed = { &xfseed }, *xflast = &xfseed;
268			register struct xfn *xp;
269			register RAY *rp;
270
271			/*
272			* Search for transform in circular list that
273			* has no associated ray in the tree.
274			*/
275			xp = xflast;
276			for (rp = r->parent; rp != NULL; rp = rp->parent)
277			if (rp->rox == &xp->xf) { /* xp in use */
278			xp = xp->next; /* move to next */
279			if (xp == xflast) { /* need new one */
280	greg	1.14	xp = (struct xfn *)bmalloc(sizeof(struct xfn));
281	greg	1.12	if (xp == NULL)
282			error(SYSTEM,
283			"out of memory in newrayxf");
284			/* insert in list */
285			xp->next = xflast->next;
286			xflast->next = xp;
287			break; /* we're done */
288			}
289			rp = r; /* start check over */
290			}
291			/* got it */
292			r->rox = &xp->xf;
293			xflast = xp;
294	greg	1.1	}
295
296
297			flipsurface(r) /* reverse surface orientation */
298			register RAY *r;
299			{
300			r->rod = -r->rod;
301			r->ron[0] = -r->ron[0];
302			r->ron[1] = -r->ron[1];
303			r->ron[2] = -r->ron[2];
304			r->pert[0] = -r->pert[0];
305			r->pert[1] = -r->pert[1];
306			r->pert[2] = -r->pert[2];
307			}
308
309
310			localhit(r, scene) /* check for hit in the octree */
311			register RAY *r;
312			register CUBE *scene;
313			{
314			FVECT curpos; /* current cube position */
315	greg	1.11	int sflags; /* sign flags */
316	greg	1.1	double t, dt;
317			register int i;
318
319	greg	1.21	nrays++; /* increment trace counter */
320	greg	1.11	sflags = 0;
321	greg	1.1	for (i = 0; i < 3; i++) {
322			curpos[i] = r->rorg[i];
323			if (r->rdir[i] > FTINY)
324	greg	1.11	sflags \|= 1 << i;
325	greg	1.1	else if (r->rdir[i] < -FTINY)
326	greg	1.11	sflags \|= 0x10 << i;
327	greg	1.1	}
328	greg	1.17	if (sflags == 0)
329			error(CONSISTENCY, "zero ray direction in localhit");
330	greg	1.1	t = 0.0;
331			if (!incube(scene, curpos)) {
332			/* find distance to entry */
333			for (i = 0; i < 3; i++) {
334			/* plane in our direction */
335	greg	1.11	if (sflags & 1<<i)
336	greg	1.1	dt = scene->cuorg[i];
337	greg	1.11	else if (sflags & 0x10<<i)
338	greg	1.1	dt = scene->cuorg[i] + scene->cusize;
339			else
340			continue;
341			/* distance to the plane */
342			dt = (dt - r->rorg[i])/r->rdir[i];
343			if (dt > t)
344			t = dt; /* farthest face is the one */
345			}
346			t += FTINY; /* fudge to get inside cube */
347			/* advance position */
348			for (i = 0; i < 3; i++)
349			curpos[i] += r->rdir[i]*t;
350
351			if (!incube(scene, curpos)) /* non-intersecting ray */
352			return(0);
353			}
354	greg	1.11	return(raymove(curpos, sflags, r, scene) == RAYHIT);
355	greg	1.1	}
356
357
358			static int
359	greg	1.11	raymove(pos, dirf, r, cu) /* check for hit as we move */
360	greg	1.1	FVECT pos; /* modified */
361	greg	1.11	int dirf; /* direction indicators to speed tests */
362	greg	1.1	register RAY *r;
363			register CUBE *cu;
364			{
365			int ax;
366			double dt, t;
367
368			if (istree(cu->cutree)) { /* recurse on subcubes */
369			CUBE cukid;
370	greg	1.11	register int br, sgn;
371	greg	1.1
372			cukid.cusize = cu->cusize * 0.5; /* find subcube */
373			VCOPY(cukid.cuorg, cu->cuorg);
374			br = 0;
375			if (pos[0] >= cukid.cuorg[0]+cukid.cusize) {
376			cukid.cuorg[0] += cukid.cusize;
377			br \|= 1;
378			}
379			if (pos[1] >= cukid.cuorg[1]+cukid.cusize) {
380			cukid.cuorg[1] += cukid.cusize;
381			br \|= 2;
382			}
383			if (pos[2] >= cukid.cuorg[2]+cukid.cusize) {
384			cukid.cuorg[2] += cukid.cusize;
385			br \|= 4;
386			}
387			for ( ; ; ) {
388			cukid.cutree = octkid(cu->cutree, br);
389	greg	1.11	if ((ax = raymove(pos,dirf,r,&cukid)) == RAYHIT)
390	greg	1.1	return(RAYHIT);
391			sgn = 1 << ax;
392	greg	1.11	if (sgn & dirf) /* positive axis? */
393	greg	1.1	if (sgn & br)
394			return(ax); /* overflow */
395			else {
396			cukid.cuorg[ax] += cukid.cusize;
397			br \|= sgn;
398			}
399	greg	1.11	else
400			if (sgn & br) {
401			cukid.cuorg[ax] -= cukid.cusize;
402			br &= ~sgn;
403			} else
404			return(ax); /* underflow */
405	greg	1.1	}
406			/NOTREACHED/
407			}
408			if (isfull(cu->cutree) && checkhit(r, cu))
409			return(RAYHIT);
410			/* advance to next cube */
411	greg	1.11	if (dirf&0x11) {
412			dt = dirf&1 ? cu->cuorg[0] + cu->cusize : cu->cuorg[0];
413	greg	1.1	t = (dt - pos[0])/r->rdir[0];
414			ax = 0;
415			} else
416			t = FHUGE;
417	greg	1.11	if (dirf&0x22) {
418			dt = dirf&2 ? cu->cuorg[1] + cu->cusize : cu->cuorg[1];
419	greg	1.1	dt = (dt - pos[1])/r->rdir[1];
420			if (dt < t) {
421			t = dt;
422			ax = 1;
423			}
424			}
425	greg	1.11	if (dirf&0x44) {
426			dt = dirf&4 ? cu->cuorg[2] + cu->cusize : cu->cuorg[2];
427	greg	1.1	dt = (dt - pos[2])/r->rdir[2];
428			if (dt < t) {
429			t = dt;
430			ax = 2;
431			}
432			}
433			pos[0] += r->rdir[0]*t;
434			pos[1] += r->rdir[1]*t;
435			pos[2] += r->rdir[2]*t;
436			return(ax);
437			}
438
439
440			static
441			checkhit(r, cu) /* check for hit in full cube */
442			register RAY *r;
443			CUBE *cu;
444			{
445			OBJECT oset[MAXSET+1];
446			register OBJREC *o;
447			register int i;
448
449			objset(oset, cu->cutree);
450			for (i = oset[0]; i > 0; i--) {
451			o = objptr(oset[i]);
452			if (o->lastrno == r->rno) /* checked already? */
453			continue;
454			(*ofun[o->otype].funp)(o, r);
455			o->lastrno = r->rno;
456			}
457			if (r->ro == NULL)
458			return(0); /* no scores yet */
459
460			return(incube(cu, r->rop)); /* hit OK if in current cube */
461			}