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 FLOAT  Lambfa[5] = {PI, PI, PI, 0.0, 0.0};
OBJREC  Lamb = {
        OVOID, MAT_PLASTIC, "Lambertian",
        {0, 5, NULL, Lambfa}, NULL,
};                                      /* 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);
        }
        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->cxs[0] = 0;
        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;
}


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 */
                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);
        }
        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);
        checkset(oset, r->cxs);                 /* eliminate double-checking */
        for (i = oset[0]; i > 0; i--) {
                o = objptr(oset[i]);
                (*ofun[o->otype].funp)(o, r);
        }
        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[MAXSET+1];          /* os' = os - cs */
register OBJECT  cs[MAXCSET+1];         /* cs' = cs + os */
{
        OBJECT  cset[MAXCSET+MAXSET+1];
        register int  i, j, 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];
                }
        }
        while (j <= cs[0])              /* get the rest of cs */
                cset[++cset[0]] = cs[j++];
        if (cset[0] > MAXCSET)          /* truncate if necessary */
                cset[0] = MAXCSET;
        setcopy(cs, cset);              /* copy new "checked" set back */
        os[0] = k;                      /* new "to check" set size */
}
Revision:	2.2
Committed:	Mon Jan 25 15:16:59 1993 UTC (31 years, 3 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.1:	+30 -6 lines
Log Message:	modified OBJREC and RAY structures to avoid redundant intersection testing using sets instead of flags
#	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	1.23	static FLOAT Lambfa[5] = {PI, PI, PI, 0.0, 0.0};
30	greg	1.15	OBJREC Lamb = {
31			OVOID, MAT_PLASTIC, "Lambertian",
32	greg	2.2	{0, 5, NULL, Lambfa}, NULL,
33	greg	1.15	}; /* 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	1.22	rayclear(r);
68			return(r->rlvl <= maxdepth && r->rweight >= minweight ? 0 : -1);
69			}
70
71
72			rayclear(r) /* clear a ray for (re)evaluation */
73			register RAY *r;
74			{
75	greg	1.20	r->rno = raynum++;
76	greg	2.2	r->cxs[0] = 0;
77	greg	1.1	r->newcset = r->clipset;
78			r->ro = NULL;
79			r->rot = FHUGE;
80			r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
81			setcolor(r->pcol, 1.0, 1.0, 1.0);
82			setcolor(r->rcol, 0.0, 0.0, 0.0);
83	greg	1.10	r->rt = 0.0;
84	greg	1.1	}
85
86
87	greg	1.21	raytrace(r) /* trace a ray and compute its value */
88	greg	1.8	RAY *r;
89	greg	1.1	{
90			extern int (*trace)();
91
92	greg	1.15	if (localhit(r, &thescene))
93	greg	1.8	raycont(r);
94	greg	1.15	else if (sourcehit(r))
95			rayshade(r, r->ro->omod);
96	greg	1.1
97			if (trace != NULL)
98			(trace)(r); / trace execution */
99			}
100
101
102	greg	1.8	raycont(r) /* check for clipped object and continue */
103			register RAY *r;
104			{
105			if (r->clipset != NULL && inset(r->clipset, r->ro->omod))
106			raytrans(r);
107			else
108			rayshade(r, r->ro->omod);
109			}
110
111
112	greg	1.1	raytrans(r) /* transmit ray as is */
113	greg	1.8	register RAY *r;
114	greg	1.1	{
115			RAY tr;
116
117			if (rayorigin(&tr, r, TRANS, 1.0) == 0) {
118			VCOPY(tr.rdir, r->rdir);
119			rayvalue(&tr);
120			copycolor(r->rcol, tr.rcol);
121	greg	1.10	r->rt = r->rot + tr.rt;
122	greg	1.1	}
123			}
124
125
126			rayshade(r, mod) /* shade ray r with material mod */
127			register RAY *r;
128			int mod;
129			{
130			static int depth = 0;
131			register OBJREC *m;
132			/* check for infinite loop */
133			if (depth++ >= MAXLOOP)
134	greg	1.4	objerror(r->ro, USER, "possible modifier loop");
135	greg	1.19	r->rt = r->rot; /* set effective ray length */
136	greg	1.1	for ( ; mod != OVOID; mod = m->omod) {
137			m = objptr(mod);
138	greg	1.4	/****** unnecessary test since modifier() is always called
139	greg	1.1	if (!ismodifier(m->otype)) {
140			sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
141			error(USER, errmsg);
142			}
143	greg	1.4	******/
144	greg	1.16	/* hack for irradiance calculation */
145			if (do_irrad && !(r->crtype & ~(PRIMARY\|TRANS))) {
146			if (irr_ignore(m->otype)) {
147			depth--;
148			raytrans(r);
149			return;
150			}
151	greg	1.18	if (!islight(m->otype))
152	greg	1.16	m = &Lamb;
153			}
154	greg	1.1	(ofun[m->otype].funp)(m, r); / execute function */
155			if (ismaterial(m->otype)) { /* materials call raytexture */
156			depth--;
157			return; /* we're done */
158			}
159			}
160			objerror(r->ro, USER, "material not found");
161			}
162
163
164			raytexture(r, mod) /* get material modifiers */
165			RAY *r;
166			int mod;
167			{
168			static int depth = 0;
169			register OBJREC *m;
170			/* check for infinite loop */
171			if (depth++ >= MAXLOOP)
172			objerror(r->ro, USER, "modifier loop");
173			/* execute textures and patterns */
174			for ( ; mod != OVOID; mod = m->omod) {
175			m = objptr(mod);
176			if (!istexture(m->otype)) {
177			sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
178			error(USER, errmsg);
179			}
180			(*ofun[m->otype].funp)(m, r);
181			}
182			depth--; /* end here */
183			}
184
185
186			raymixture(r, fore, back, coef) /* mix modifiers */
187			register RAY *r;
188			OBJECT fore, back;
189			double coef;
190			{
191			FVECT curpert, forepert, backpert;
192			COLOR curpcol, forepcol, backpcol;
193			register int i;
194			/* clip coefficient */
195			if (coef > 1.0)
196			coef = 1.0;
197			else if (coef < 0.0)
198			coef = 0.0;
199			/* save current mods */
200			VCOPY(curpert, r->pert);
201			copycolor(curpcol, r->pcol);
202			/* compute new mods */
203			/* foreground */
204			r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
205			setcolor(r->pcol, 1.0, 1.0, 1.0);
206			if (fore != OVOID && coef > FTINY)
207			raytexture(r, fore);
208			VCOPY(forepert, r->pert);
209			copycolor(forepcol, r->pcol);
210			/* background */
211			r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
212			setcolor(r->pcol, 1.0, 1.0, 1.0);
213			if (back != OVOID && coef < 1.0-FTINY)
214			raytexture(r, back);
215			VCOPY(backpert, r->pert);
216			copycolor(backpcol, r->pcol);
217			/* sum perturbations */
218			for (i = 0; i < 3; i++)
219			r->pert[i] = curpert[i] + coef*forepert[i] +
220			(1.0-coef)*backpert[i];
221			/* multiply colors */
222			setcolor(r->pcol, coef*colval(forepcol,RED) +
223			(1.0-coef)*colval(backpcol,RED),
224			coef*colval(forepcol,GRN) +
225			(1.0-coef)*colval(backpcol,GRN),
226			coef*colval(forepcol,BLU) +
227			(1.0-coef)*colval(backpcol,BLU));
228			multcolor(r->pcol, curpcol);
229			}
230
231
232			double
233			raynormal(norm, r) /* compute perturbed normal for ray */
234			FVECT norm;
235			register RAY *r;
236			{
237			double newdot;
238			register int i;
239
240			/* The perturbation is added to the surface normal to obtain
241			* the new normal. If the new normal would affect the surface
242			* orientation wrt. the ray, a correction is made. The method is
243			* still fraught with problems since reflected rays and similar
244			* directions calculated from the surface normal may spawn rays behind
245			* the surface. The only solution is to curb textures at high
246	greg	1.9	* incidence (namely, keep DOT(rdir,pert) < Rdot).
247	greg	1.1	*/
248
249			for (i = 0; i < 3; i++)
250			norm[i] = r->ron[i] + r->pert[i];
251
252			if (normalize(norm) == 0.0) {
253			objerror(r->ro, WARNING, "illegal normal perturbation");
254			VCOPY(norm, r->ron);
255			return(r->rod);
256			}
257			newdot = -DOT(norm, r->rdir);
258			if ((newdot > 0.0) != (r->rod > 0.0)) { /* fix orientation */
259			for (i = 0; i < 3; i++)
260			norm[i] += 2.0newdotr->rdir[i];
261			newdot = -newdot;
262			}
263			return(newdot);
264	greg	1.12	}
265
266
267			newrayxf(r) /* get new tranformation matrix for ray */
268			RAY *r;
269			{
270			static struct xfn {
271			struct xfn *next;
272			FULLXF xf;
273			} xfseed = { &xfseed }, *xflast = &xfseed;
274			register struct xfn *xp;
275			register RAY *rp;
276
277			/*
278			* Search for transform in circular list that
279			* has no associated ray in the tree.
280			*/
281			xp = xflast;
282			for (rp = r->parent; rp != NULL; rp = rp->parent)
283			if (rp->rox == &xp->xf) { /* xp in use */
284			xp = xp->next; /* move to next */
285			if (xp == xflast) { /* need new one */
286	greg	1.14	xp = (struct xfn *)bmalloc(sizeof(struct xfn));
287	greg	1.12	if (xp == NULL)
288			error(SYSTEM,
289			"out of memory in newrayxf");
290			/* insert in list */
291			xp->next = xflast->next;
292			xflast->next = xp;
293			break; /* we're done */
294			}
295			rp = r; /* start check over */
296			}
297			/* got it */
298			r->rox = &xp->xf;
299			xflast = xp;
300	greg	1.1	}
301
302
303			flipsurface(r) /* reverse surface orientation */
304			register RAY *r;
305			{
306			r->rod = -r->rod;
307			r->ron[0] = -r->ron[0];
308			r->ron[1] = -r->ron[1];
309			r->ron[2] = -r->ron[2];
310			r->pert[0] = -r->pert[0];
311			r->pert[1] = -r->pert[1];
312			r->pert[2] = -r->pert[2];
313			}
314
315
316			localhit(r, scene) /* check for hit in the octree */
317			register RAY *r;
318			register CUBE *scene;
319			{
320			FVECT curpos; /* current cube position */
321	greg	1.11	int sflags; /* sign flags */
322	greg	1.1	double t, dt;
323			register int i;
324
325	greg	1.21	nrays++; /* increment trace counter */
326	greg	1.11	sflags = 0;
327	greg	1.1	for (i = 0; i < 3; i++) {
328			curpos[i] = r->rorg[i];
329			if (r->rdir[i] > FTINY)
330	greg	1.11	sflags \|= 1 << i;
331	greg	1.1	else if (r->rdir[i] < -FTINY)
332	greg	1.11	sflags \|= 0x10 << i;
333	greg	1.1	}
334	greg	1.17	if (sflags == 0)
335			error(CONSISTENCY, "zero ray direction in localhit");
336	greg	1.1	t = 0.0;
337			if (!incube(scene, curpos)) {
338			/* find distance to entry */
339			for (i = 0; i < 3; i++) {
340			/* plane in our direction */
341	greg	1.11	if (sflags & 1<<i)
342	greg	1.1	dt = scene->cuorg[i];
343	greg	1.11	else if (sflags & 0x10<<i)
344	greg	1.1	dt = scene->cuorg[i] + scene->cusize;
345			else
346			continue;
347			/* distance to the plane */
348			dt = (dt - r->rorg[i])/r->rdir[i];
349			if (dt > t)
350			t = dt; /* farthest face is the one */
351			}
352			t += FTINY; /* fudge to get inside cube */
353			/* advance position */
354			for (i = 0; i < 3; i++)
355			curpos[i] += r->rdir[i]*t;
356
357			if (!incube(scene, curpos)) /* non-intersecting ray */
358			return(0);
359			}
360	greg	1.11	return(raymove(curpos, sflags, r, scene) == RAYHIT);
361	greg	1.1	}
362
363
364			static int
365	greg	1.11	raymove(pos, dirf, r, cu) /* check for hit as we move */
366	greg	1.1	FVECT pos; /* modified */
367	greg	1.11	int dirf; /* direction indicators to speed tests */
368	greg	1.1	register RAY *r;
369			register CUBE *cu;
370			{
371			int ax;
372			double dt, t;
373
374			if (istree(cu->cutree)) { /* recurse on subcubes */
375			CUBE cukid;
376	greg	1.11	register int br, sgn;
377	greg	1.1
378			cukid.cusize = cu->cusize * 0.5; /* find subcube */
379			VCOPY(cukid.cuorg, cu->cuorg);
380			br = 0;
381			if (pos[0] >= cukid.cuorg[0]+cukid.cusize) {
382			cukid.cuorg[0] += cukid.cusize;
383			br \|= 1;
384			}
385			if (pos[1] >= cukid.cuorg[1]+cukid.cusize) {
386			cukid.cuorg[1] += cukid.cusize;
387			br \|= 2;
388			}
389			if (pos[2] >= cukid.cuorg[2]+cukid.cusize) {
390			cukid.cuorg[2] += cukid.cusize;
391			br \|= 4;
392			}
393			for ( ; ; ) {
394			cukid.cutree = octkid(cu->cutree, br);
395	greg	1.11	if ((ax = raymove(pos,dirf,r,&cukid)) == RAYHIT)
396	greg	1.1	return(RAYHIT);
397			sgn = 1 << ax;
398	greg	1.11	if (sgn & dirf) /* positive axis? */
399	greg	1.1	if (sgn & br)
400			return(ax); /* overflow */
401			else {
402			cukid.cuorg[ax] += cukid.cusize;
403			br \|= sgn;
404			}
405	greg	1.11	else
406			if (sgn & br) {
407			cukid.cuorg[ax] -= cukid.cusize;
408			br &= ~sgn;
409			} else
410			return(ax); /* underflow */
411	greg	1.1	}
412			/NOTREACHED/
413			}
414			if (isfull(cu->cutree) && checkhit(r, cu))
415			return(RAYHIT);
416			/* advance to next cube */
417	greg	1.11	if (dirf&0x11) {
418			dt = dirf&1 ? cu->cuorg[0] + cu->cusize : cu->cuorg[0];
419	greg	1.1	t = (dt - pos[0])/r->rdir[0];
420			ax = 0;
421			} else
422			t = FHUGE;
423	greg	1.11	if (dirf&0x22) {
424			dt = dirf&2 ? cu->cuorg[1] + cu->cusize : cu->cuorg[1];
425	greg	1.1	dt = (dt - pos[1])/r->rdir[1];
426			if (dt < t) {
427			t = dt;
428			ax = 1;
429			}
430			}
431	greg	1.11	if (dirf&0x44) {
432			dt = dirf&4 ? cu->cuorg[2] + cu->cusize : cu->cuorg[2];
433	greg	1.1	dt = (dt - pos[2])/r->rdir[2];
434			if (dt < t) {
435			t = dt;
436			ax = 2;
437			}
438			}
439			pos[0] += r->rdir[0]*t;
440			pos[1] += r->rdir[1]*t;
441			pos[2] += r->rdir[2]*t;
442			return(ax);
443			}
444
445
446			static
447			checkhit(r, cu) /* check for hit in full cube */
448			register RAY *r;
449			CUBE *cu;
450			{
451			OBJECT oset[MAXSET+1];
452			register OBJREC *o;
453			register int i;
454
455			objset(oset, cu->cutree);
456	greg	2.2	checkset(oset, r->cxs); /* eliminate double-checking */
457	greg	1.1	for (i = oset[0]; i > 0; i--) {
458			o = objptr(oset[i]);
459			(*ofun[o->otype].funp)(o, r);
460			}
461			if (r->ro == NULL)
462			return(0); /* no scores yet */
463
464			return(incube(cu, r->rop)); /* hit OK if in current cube */
465	greg	2.2	}
466
467
468			static
469			checkset(os, cs) /* modify checked set and set to check */
470			register OBJECT os[MAXSET+1]; /* os' = os - cs */
471			register OBJECT cs[MAXCSET+1]; /* cs' = cs + os */
472			{
473			OBJECT cset[MAXCSET+MAXSET+1];
474			register int i, j, k;
475			/* copy os in place, cset <- cs */
476			cset[0] = 0;
477			k = 0;
478			for (i = j = 1; i <= os[0]; i++) {
479			while (j <= cs[0] && cs[j] < os[i])
480			cset[++cset[0]] = cs[j++];
481			if (j > cs[0] \|\| os[i] != cs[j]) { /* object to check */
482			os[++k] = os[i];
483			cset[++cset[0]] = os[i];
484			}
485			}
486			while (j <= cs[0]) /* get the rest of cs */
487			cset[++cset[0]] = cs[j++];
488			if (cset[0] > MAXCSET) /* truncate if necessary */
489			cset[0] = MAXCSET;
490			setcopy(cs, cset); /* copy new "checked" set back */
491			os[0] = k; /* new "to check" set size */
492	greg	1.1	}