src/rt/raytrace.c

/* Copyright (c) 1986 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"

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

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

#define  MAXLOOP        32              /* 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->rofs = 1.0; setident4(r->rofx);
        r->robs = 1.0; setident4(r->robx);
        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);
        return(r->rlvl <= maxdepth && r->rweight >= minweight ? 0 : -1);
}


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

        if (localhit(r, &thescene))
                if (r->clipset != NULL && inset(r->clipset, r->ro->omod))
                        raytrans(r);            /* object is clipped */
                else
                        rayshade(r, r->ro->omod);
        else if (sourcehit(r))
                rayshade(r, r->ro->omod);

        if (trace != NULL)
                (*trace)(r);            /* trace execution */
}


raytrans(r)                     /* transmit ray as is */
RAY  *r;
{
        RAY  tr;

        if (rayorigin(&tr, r, TRANS, 1.0) == 0) {
                VCOPY(tr.rdir, r->rdir);
                rayvalue(&tr);
                copycolor(r->rcol, tr.rcol);
        }
}


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, "material loop");
        for ( ; mod != OVOID; mod = m->omod) {
                m = objptr(mod);
                if (!ismodifier(m->otype)) {
                        sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
                        error(USER, errmsg);
                }
                (*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 (Rdot << 1).
         */

        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);
}


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  mpos, mneg;                /* sign flags */
        double  t, dt;
        register int  i;

        nrays++;                        /* increment trace counter */

        mpos = mneg = 0;
        for (i = 0; i < 3; i++) {
                curpos[i] = r->rorg[i];
                if (r->rdir[i] > FTINY)
                        mpos |= 1 << i;
                else if (r->rdir[i] < -FTINY)
                        mneg |= 1 << i;
        }
        t = 0.0;
        if (!incube(scene, curpos)) {
                                        /* find distance to entry */
                for (i = 0; i < 3; i++) {
                                        /* plane in our direction */
                        if (mpos & 1<<i)
                                dt = scene->cuorg[i];
                        else if (mneg & 1<<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, mpos, mneg, r, scene) == RAYHIT);
}


static int
raymove(pos, plus, minus, r, cu)        /* check for hit as we move */
FVECT  pos;                     /* modified */
int  plus, minus;               /* direction indicators to speed tests */
register RAY  *r;
register CUBE  *cu;
{
        int  ax;
        double  dt, t;
        register int  sgn;

        if (istree(cu->cutree)) {               /* recurse on subcubes */
                CUBE  cukid;
                register int  br;

                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,plus,minus,r,&cukid)) == RAYHIT)
                                return(RAYHIT);
                        sgn = 1 << ax;
                        if (sgn & minus)                /* negative axis? */
                                if (sgn & br) {
                                        cukid.cuorg[ax] -= cukid.cusize;
                                        br &= ~sgn;
                                } else
                                        return(ax);     /* underflow */
                        else
                                if (sgn & br)
                                        return(ax);     /* overflow */
                                else {
                                        cukid.cuorg[ax] += cukid.cusize;
                                        br |= sgn;
                                }
                }
                /*NOTREACHED*/
        }
        if (isfull(cu->cutree) && checkhit(r, cu))
                return(RAYHIT);
                                        /* advance to next cube */
        sgn = plus | minus;
        if (sgn&1) {
                dt = plus&1 ? cu->cuorg[0] + cu->cusize : cu->cuorg[0];
                t = (dt - pos[0])/r->rdir[0];
                ax = 0;
        } else
                t = FHUGE;
        if (sgn&2) {
                dt = plus&2 ? cu->cuorg[1] + cu->cusize : cu->cuorg[1];
                dt = (dt - pos[1])/r->rdir[1];
                if (dt < t) {
                        t = dt;
                        ax = 1;
                }
        }
        if (sgn&4) {
                dt = plus&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:	1.2
Committed:	Tue Apr 11 13:30:31 1989 UTC (35 years ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 1.1:	+2 -1 lines
Log Message:	fixed bugs in instance mapping of modifiers
#	User	Rev	Content
1	greg	1.1	/* Copyright (c) 1986 Regents of the University of California */
2
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			extern CUBE thescene; /* our scene */
20			extern int maxdepth; /* maximum recursion depth */
21			extern double minweight; /* minimum ray weight */
22
23			long nrays = 0L; /* number of rays traced */
24
25			#define MAXLOOP 32 /* modifier loop detection */
26
27			#define RAYHIT (-1) /* return value for intercepted ray */
28
29
30			rayorigin(r, ro, rt, rw) /* start new ray from old one */
31			register RAY r, ro;
32			int rt;
33			double rw;
34			{
35			if ((r->parent = ro) == NULL) { /* primary ray */
36			r->rlvl = 0;
37			r->rweight = rw;
38			r->crtype = r->rtype = rt;
39			r->rsrc = -1;
40			r->clipset = NULL;
41			} else { /* spawned ray */
42			r->rlvl = ro->rlvl;
43			if (rt & RAYREFL) {
44			r->rlvl++;
45			r->rsrc = -1;
46			r->clipset = ro->clipset;
47			} else {
48			r->rsrc = ro->rsrc;
49			r->clipset = ro->newcset;
50			}
51			r->rweight = ro->rweight * rw;
52			r->crtype = ro->crtype \| (r->rtype = rt);
53			VCOPY(r->rorg, ro->rop);
54			}
55			r->rno = nrays;
56			r->newcset = r->clipset;
57			r->ro = NULL;
58			r->rot = FHUGE;
59	greg	1.2	r->rofs = 1.0; setident4(r->rofx);
60			r->robs = 1.0; setident4(r->robx);
61	greg	1.1	r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
62			setcolor(r->pcol, 1.0, 1.0, 1.0);
63			setcolor(r->rcol, 0.0, 0.0, 0.0);
64			return(r->rlvl <= maxdepth && r->rweight >= minweight ? 0 : -1);
65			}
66
67
68			rayvalue(r) /* compute a ray's value */
69			register RAY *r;
70			{
71			extern int (*trace)();
72
73			if (localhit(r, &thescene))
74			if (r->clipset != NULL && inset(r->clipset, r->ro->omod))
75			raytrans(r); /* object is clipped */
76			else
77			rayshade(r, r->ro->omod);
78			else if (sourcehit(r))
79			rayshade(r, r->ro->omod);
80
81			if (trace != NULL)
82			(trace)(r); / trace execution */
83			}
84
85
86			raytrans(r) /* transmit ray as is */
87			RAY *r;
88			{
89			RAY tr;
90
91			if (rayorigin(&tr, r, TRANS, 1.0) == 0) {
92			VCOPY(tr.rdir, r->rdir);
93			rayvalue(&tr);
94			copycolor(r->rcol, tr.rcol);
95			}
96			}
97
98
99			rayshade(r, mod) /* shade ray r with material mod */
100			register RAY *r;
101			int mod;
102			{
103			static int depth = 0;
104			register OBJREC *m;
105			/* check for infinite loop */
106			if (depth++ >= MAXLOOP)
107			objerror(r->ro, USER, "material loop");
108			for ( ; mod != OVOID; mod = m->omod) {
109			m = objptr(mod);
110			if (!ismodifier(m->otype)) {
111			sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
112			error(USER, errmsg);
113			}
114			(ofun[m->otype].funp)(m, r); / execute function */
115			m->lastrno = r->rno;
116			if (ismaterial(m->otype)) { /* materials call raytexture */
117			depth--;
118			return; /* we're done */
119			}
120			}
121			objerror(r->ro, USER, "material not found");
122			}
123
124
125			raytexture(r, mod) /* get material modifiers */
126			RAY *r;
127			int mod;
128			{
129			static int depth = 0;
130			register OBJREC *m;
131			/* check for infinite loop */
132			if (depth++ >= MAXLOOP)
133			objerror(r->ro, USER, "modifier loop");
134			/* execute textures and patterns */
135			for ( ; mod != OVOID; mod = m->omod) {
136			m = objptr(mod);
137			if (!istexture(m->otype)) {
138			sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
139			error(USER, errmsg);
140			}
141			(*ofun[m->otype].funp)(m, r);
142			m->lastrno = r->rno;
143			}
144			depth--; /* end here */
145			}
146
147
148			raymixture(r, fore, back, coef) /* mix modifiers */
149			register RAY *r;
150			OBJECT fore, back;
151			double coef;
152			{
153			FVECT curpert, forepert, backpert;
154			COLOR curpcol, forepcol, backpcol;
155			register int i;
156			/* clip coefficient */
157			if (coef > 1.0)
158			coef = 1.0;
159			else if (coef < 0.0)
160			coef = 0.0;
161			/* save current mods */
162			VCOPY(curpert, r->pert);
163			copycolor(curpcol, r->pcol);
164			/* compute new mods */
165			/* foreground */
166			r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
167			setcolor(r->pcol, 1.0, 1.0, 1.0);
168			if (fore != OVOID && coef > FTINY)
169			raytexture(r, fore);
170			VCOPY(forepert, r->pert);
171			copycolor(forepcol, r->pcol);
172			/* background */
173			r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
174			setcolor(r->pcol, 1.0, 1.0, 1.0);
175			if (back != OVOID && coef < 1.0-FTINY)
176			raytexture(r, back);
177			VCOPY(backpert, r->pert);
178			copycolor(backpcol, r->pcol);
179			/* sum perturbations */
180			for (i = 0; i < 3; i++)
181			r->pert[i] = curpert[i] + coef*forepert[i] +
182			(1.0-coef)*backpert[i];
183			/* multiply colors */
184			setcolor(r->pcol, coef*colval(forepcol,RED) +
185			(1.0-coef)*colval(backpcol,RED),
186			coef*colval(forepcol,GRN) +
187			(1.0-coef)*colval(backpcol,GRN),
188			coef*colval(forepcol,BLU) +
189			(1.0-coef)*colval(backpcol,BLU));
190			multcolor(r->pcol, curpcol);
191			}
192
193
194			double
195			raynormal(norm, r) /* compute perturbed normal for ray */
196			FVECT norm;
197			register RAY *r;
198			{
199			double newdot;
200			register int i;
201
202			/* The perturbation is added to the surface normal to obtain
203			* the new normal. If the new normal would affect the surface
204			* orientation wrt. the ray, a correction is made. The method is
205			* still fraught with problems since reflected rays and similar
206			* directions calculated from the surface normal may spawn rays behind
207			* the surface. The only solution is to curb textures at high
208			* incidence (Rdot << 1).
209			*/
210
211			for (i = 0; i < 3; i++)
212			norm[i] = r->ron[i] + r->pert[i];
213
214			if (normalize(norm) == 0.0) {
215			objerror(r->ro, WARNING, "illegal normal perturbation");
216			VCOPY(norm, r->ron);
217			return(r->rod);
218			}
219			newdot = -DOT(norm, r->rdir);
220			if ((newdot > 0.0) != (r->rod > 0.0)) { /* fix orientation */
221			for (i = 0; i < 3; i++)
222			norm[i] += 2.0newdotr->rdir[i];
223			newdot = -newdot;
224			}
225			return(newdot);
226			}
227
228
229			flipsurface(r) /* reverse surface orientation */
230			register RAY *r;
231			{
232			r->rod = -r->rod;
233			r->ron[0] = -r->ron[0];
234			r->ron[1] = -r->ron[1];
235			r->ron[2] = -r->ron[2];
236			r->pert[0] = -r->pert[0];
237			r->pert[1] = -r->pert[1];
238			r->pert[2] = -r->pert[2];
239			}
240
241
242			localhit(r, scene) /* check for hit in the octree */
243			register RAY *r;
244			register CUBE *scene;
245			{
246			FVECT curpos; /* current cube position */
247			int mpos, mneg; /* sign flags */
248			double t, dt;
249			register int i;
250
251			nrays++; /* increment trace counter */
252
253			mpos = mneg = 0;
254			for (i = 0; i < 3; i++) {
255			curpos[i] = r->rorg[i];
256			if (r->rdir[i] > FTINY)
257			mpos \|= 1 << i;
258			else if (r->rdir[i] < -FTINY)
259			mneg \|= 1 << i;
260			}
261			t = 0.0;
262			if (!incube(scene, curpos)) {
263			/* find distance to entry */
264			for (i = 0; i < 3; i++) {
265			/* plane in our direction */
266			if (mpos & 1<<i)
267			dt = scene->cuorg[i];
268			else if (mneg & 1<<i)
269			dt = scene->cuorg[i] + scene->cusize;
270			else
271			continue;
272			/* distance to the plane */
273			dt = (dt - r->rorg[i])/r->rdir[i];
274			if (dt > t)
275			t = dt; /* farthest face is the one */
276			}
277			t += FTINY; /* fudge to get inside cube */
278			/* advance position */
279			for (i = 0; i < 3; i++)
280			curpos[i] += r->rdir[i]*t;
281
282			if (!incube(scene, curpos)) /* non-intersecting ray */
283			return(0);
284			}
285			return(raymove(curpos, mpos, mneg, r, scene) == RAYHIT);
286			}
287
288
289			static int
290			raymove(pos, plus, minus, r, cu) /* check for hit as we move */
291			FVECT pos; /* modified */
292			int plus, minus; /* direction indicators to speed tests */
293			register RAY *r;
294			register CUBE *cu;
295			{
296			int ax;
297			double dt, t;
298			register int sgn;
299
300			if (istree(cu->cutree)) { /* recurse on subcubes */
301			CUBE cukid;
302			register int br;
303
304			cukid.cusize = cu->cusize * 0.5; /* find subcube */
305			VCOPY(cukid.cuorg, cu->cuorg);
306			br = 0;
307			if (pos[0] >= cukid.cuorg[0]+cukid.cusize) {
308			cukid.cuorg[0] += cukid.cusize;
309			br \|= 1;
310			}
311			if (pos[1] >= cukid.cuorg[1]+cukid.cusize) {
312			cukid.cuorg[1] += cukid.cusize;
313			br \|= 2;
314			}
315			if (pos[2] >= cukid.cuorg[2]+cukid.cusize) {
316			cukid.cuorg[2] += cukid.cusize;
317			br \|= 4;
318			}
319			for ( ; ; ) {
320			cukid.cutree = octkid(cu->cutree, br);
321			if ((ax = raymove(pos,plus,minus,r,&cukid)) == RAYHIT)
322			return(RAYHIT);
323			sgn = 1 << ax;
324			if (sgn & minus) /* negative axis? */
325			if (sgn & br) {
326			cukid.cuorg[ax] -= cukid.cusize;
327			br &= ~sgn;
328			} else
329			return(ax); /* underflow */
330			else
331			if (sgn & br)
332			return(ax); /* overflow */
333			else {
334			cukid.cuorg[ax] += cukid.cusize;
335			br \|= sgn;
336			}
337			}
338			/NOTREACHED/
339			}
340			if (isfull(cu->cutree) && checkhit(r, cu))
341			return(RAYHIT);
342			/* advance to next cube */
343			sgn = plus \| minus;
344			if (sgn&1) {
345			dt = plus&1 ? cu->cuorg[0] + cu->cusize : cu->cuorg[0];
346			t = (dt - pos[0])/r->rdir[0];
347			ax = 0;
348			} else
349			t = FHUGE;
350			if (sgn&2) {
351			dt = plus&2 ? cu->cuorg[1] + cu->cusize : cu->cuorg[1];
352			dt = (dt - pos[1])/r->rdir[1];
353			if (dt < t) {
354			t = dt;
355			ax = 1;
356			}
357			}
358			if (sgn&4) {
359			dt = plus&4 ? cu->cuorg[2] + cu->cusize : cu->cuorg[2];
360			dt = (dt - pos[2])/r->rdir[2];
361			if (dt < t) {
362			t = dt;
363			ax = 2;
364			}
365			}
366			pos[0] += r->rdir[0]*t;
367			pos[1] += r->rdir[1]*t;
368			pos[2] += r->rdir[2]*t;
369			return(ax);
370			}
371
372
373			static
374			checkhit(r, cu) /* check for hit in full cube */
375			register RAY *r;
376			CUBE *cu;
377			{
378			OBJECT oset[MAXSET+1];
379			register OBJREC *o;
380			register int i;
381
382			objset(oset, cu->cutree);
383			for (i = oset[0]; i > 0; i--) {
384			o = objptr(oset[i]);
385			if (o->lastrno == r->rno) /* checked already? */
386			continue;
387			(*ofun[o->otype].funp)(o, r);
388			o->lastrno = r->rno;
389			}
390			if (r->ro == NULL)
391			return(0); /* no scores yet */
392
393			return(incube(cu, r->rop)); /* hit OK if in current cube */
394			}