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"

#define  MAXCSET        ((MAXSET+1)*2-1)        /* maximum check set size */

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

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->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;
{
        OBJECT  cxset[MAXCSET+1];       /* set of checked objects */
        FVECT  curpos;                  /* current cube position */
        int  sflags;                    /* sign flags */
        double  t, dt;
        register int  i;

        nrays++;                        /* increment trace counter */
        sflags = 0;
        for (i = 0; i < 3; i++) {
                curpos[i] = r->rorg[i];
                if (r->rdir[i] > 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);
        }
        cxset[0] = 0;
        return(raymove(curpos, cxset, sflags, r, scene) == RAYHIT);
}


static int
raymove(pos, cxs, dirf, r, cu)          /* check for hit as we move */
FVECT  pos;                     /* current position, modified herein */
OBJECT  *cxs;                   /* checked objects, modified by checkhit */
int  dirf;                      /* direction indicators to speed tests */
register RAY  *r;
register CUBE  *cu;
{
        int  ax;
        double  dt, t;

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

                cukid.cusize = cu->cusize * 0.5;        /* find subcube */
                VCOPY(cukid.cuorg, cu->cuorg);
                br = 0;
                if (pos[0] >= cukid.cuorg[0]+cukid.cusize) {
                        cukid.cuorg[0] += cukid.cusize;
                        br |= 1;
                }
                if (pos[1] >= cukid.cuorg[1]+cukid.cusize) {
                        cukid.cuorg[1] += cukid.cusize;
                        br |= 2;
                }
                if (pos[2] >= cukid.cuorg[2]+cukid.cusize) {
                        cukid.cuorg[2] += cukid.cusize;
                        br |= 4;
                }
                for ( ; ; ) {
                        cukid.cutree = octkid(cu->cutree, br);
                        if ((ax = raymove(pos,cxs,dirf,r,&cukid)) == RAYHIT)
                                return(RAYHIT);
                        sgn = 1 << ax;
                        if (sgn & dirf)                 /* positive axis? */
                                if (sgn & br)
                                        return(ax);     /* overflow */
                                else {
                                        cukid.cuorg[ax] += cukid.cusize;
                                        br |= sgn;
                                }
                        else
                                if (sgn & br) {
                                        cukid.cuorg[ax] -= cukid.cusize;
                                        br &= ~sgn;
                                } else
                                        return(ax);     /* underflow */
                }
                /*NOTREACHED*/
        }
        if (isfull(cu->cutree) && checkhit(r, cu, cxs))
                return(RAYHIT);
                                        /* advance to next cube */
        if (dirf&0x11) {
                dt = dirf&1 ? cu->cuorg[0] + cu->cusize : cu->cuorg[0];
                t = (dt - pos[0])/r->rdir[0];
                ax = 0;
        } else
                t = FHUGE;
        if (dirf&0x22) {
                dt = dirf&2 ? cu->cuorg[1] + cu->cusize : cu->cuorg[1];
                dt = (dt - pos[1])/r->rdir[1];
                if (dt < t) {
                        t = dt;
                        ax = 1;
                }
        }
        if (dirf&0x44) {
                dt = dirf&4 ? cu->cuorg[2] + cu->cusize : cu->cuorg[2];
                dt = (dt - pos[2])/r->rdir[2];
                if (dt < t) {
                        t = dt;
                        ax = 2;
                }
        }
        pos[0] += r->rdir[0]*t;
        pos[1] += r->rdir[1]*t;
        pos[2] += r->rdir[2]*t;
        return(ax);
}


static
checkhit(r, cu, cxs)            /* check for hit in full cube */
register RAY  *r;
CUBE  *cu;
OBJECT  *cxs;
{
        OBJECT  oset[MAXSET+1];
        register OBJREC  *o;
        register int  i;

        objset(oset, cu->cutree);
        checkset(oset, cxs);                    /* eliminate double-checking */
        for (i = oset[0]; i > 0; i--) {
                o = objptr(oset[i]);
                if (o->omod == OVOID && issurface(o->otype))
                        continue;               /* ignore void surfaces */
                (*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;                   /* os' = os - cs */
register OBJECT  *cs;                   /* cs' = cs + os */
{
        OBJECT  cset[MAXCSET+MAXSET+1];
        register int  i, j;
        int  k;
                                        /* copy os in place, cset <- cs */
        cset[0] = 0;
        k = 0;
        for (i = j = 1; i <= os[0]; i++) {
                while (j <= cs[0] && cs[j] < os[i])
                        cset[++cset[0]] = cs[j++];
                if (j > cs[0] || os[i] != cs[j]) {      /* object to check */
                        os[++k] = os[i];
                        cset[++cset[0]] = os[i];
                }
        }
        if (!(os[0] = k))               /* new "to check" set size */
                return;                 /* special case */
        while (j <= cs[0])              /* get the rest of cs */
                cset[++cset[0]] = cs[j++];
        if (cset[0] > MAXCSET)          /* truncate "checked" set if nec. */
                cset[0] = MAXCSET;
        /* setcopy(cs, cset); */        /* copy cset back to cs */
        os = cset;
        for (i = os[0]; i-- >= 0; )
                *cs++ = *os++;
}
Revision:	2.4
Committed:	Tue Feb 23 13:57:11 1993 UTC (31 years, 2 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.3:	+2 -0 lines
Log Message:	made void surfaces legal
#	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	2.3	#define MAXCSET ((MAXSET+1)2-1) / maximum check set size */
22
23	greg	1.1	extern CUBE thescene; /* our scene */
24			extern int maxdepth; /* maximum recursion depth */
25			extern double minweight; /* minimum ray weight */
26	greg	1.15	extern int do_irrad; /* compute irradiance? */
27	greg	1.1
28	greg	1.20	long raynum = 0L; /* next unique ray number */
29	greg	1.21	long nrays = 0L; /* number of calls to localhit */
30	greg	1.1
31	greg	1.23	static FLOAT Lambfa[5] = {PI, PI, PI, 0.0, 0.0};
32	greg	1.15	OBJREC Lamb = {
33			OVOID, MAT_PLASTIC, "Lambertian",
34	greg	2.2	{0, 5, NULL, Lambfa}, NULL,
35	greg	1.15	}; /* a Lambertian surface */
36
37	greg	1.6	#define MAXLOOP 128 /* modifier loop detection */
38	greg	1.1
39			#define RAYHIT (-1) /* return value for intercepted ray */
40
41
42			rayorigin(r, ro, rt, rw) /* start new ray from old one */
43			register RAY r, ro;
44			int rt;
45			double rw;
46			{
47			if ((r->parent = ro) == NULL) { /* primary ray */
48			r->rlvl = 0;
49			r->rweight = rw;
50			r->crtype = r->rtype = rt;
51			r->rsrc = -1;
52			r->clipset = NULL;
53	greg	1.21	r->revf = raytrace;
54	greg	1.1	} else { /* spawned ray */
55			r->rlvl = ro->rlvl;
56			if (rt & RAYREFL) {
57			r->rlvl++;
58			r->rsrc = -1;
59			r->clipset = ro->clipset;
60			} else {
61			r->rsrc = ro->rsrc;
62			r->clipset = ro->newcset;
63			}
64	greg	1.21	r->revf = ro->revf;
65	greg	1.1	r->rweight = ro->rweight * rw;
66			r->crtype = ro->crtype \| (r->rtype = rt);
67			VCOPY(r->rorg, ro->rop);
68			}
69	greg	1.22	rayclear(r);
70			return(r->rlvl <= maxdepth && r->rweight >= minweight ? 0 : -1);
71			}
72
73
74			rayclear(r) /* clear a ray for (re)evaluation */
75			register RAY *r;
76			{
77	greg	1.20	r->rno = raynum++;
78	greg	1.1	r->newcset = r->clipset;
79			r->ro = NULL;
80			r->rot = FHUGE;
81			r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
82			setcolor(r->pcol, 1.0, 1.0, 1.0);
83			setcolor(r->rcol, 0.0, 0.0, 0.0);
84	greg	1.10	r->rt = 0.0;
85	greg	1.1	}
86
87
88	greg	1.21	raytrace(r) /* trace a ray and compute its value */
89	greg	1.8	RAY *r;
90	greg	1.1	{
91			extern int (*trace)();
92
93	greg	1.15	if (localhit(r, &thescene))
94	greg	1.8	raycont(r);
95	greg	1.15	else if (sourcehit(r))
96			rayshade(r, r->ro->omod);
97	greg	1.1
98			if (trace != NULL)
99			(trace)(r); / trace execution */
100			}
101
102
103	greg	1.8	raycont(r) /* check for clipped object and continue */
104			register RAY *r;
105			{
106			if (r->clipset != NULL && inset(r->clipset, r->ro->omod))
107			raytrans(r);
108			else
109			rayshade(r, r->ro->omod);
110			}
111
112
113	greg	1.1	raytrans(r) /* transmit ray as is */
114	greg	1.8	register RAY *r;
115	greg	1.1	{
116			RAY tr;
117
118			if (rayorigin(&tr, r, TRANS, 1.0) == 0) {
119			VCOPY(tr.rdir, r->rdir);
120			rayvalue(&tr);
121			copycolor(r->rcol, tr.rcol);
122	greg	1.10	r->rt = r->rot + tr.rt;
123	greg	1.1	}
124			}
125
126
127			rayshade(r, mod) /* shade ray r with material mod */
128			register RAY *r;
129			int mod;
130			{
131			static int depth = 0;
132			register OBJREC *m;
133			/* check for infinite loop */
134			if (depth++ >= MAXLOOP)
135	greg	1.4	objerror(r->ro, USER, "possible modifier loop");
136	greg	1.19	r->rt = r->rot; /* set effective ray length */
137	greg	1.1	for ( ; mod != OVOID; mod = m->omod) {
138			m = objptr(mod);
139	greg	1.4	/****** unnecessary test since modifier() is always called
140	greg	1.1	if (!ismodifier(m->otype)) {
141			sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
142			error(USER, errmsg);
143			}
144	greg	1.4	******/
145	greg	1.16	/* hack for irradiance calculation */
146			if (do_irrad && !(r->crtype & ~(PRIMARY\|TRANS))) {
147			if (irr_ignore(m->otype)) {
148			depth--;
149			raytrans(r);
150			return;
151			}
152	greg	1.18	if (!islight(m->otype))
153	greg	1.16	m = &Lamb;
154			}
155	greg	1.1	(ofun[m->otype].funp)(m, r); / execute function */
156			if (ismaterial(m->otype)) { /* materials call raytexture */
157			depth--;
158			return; /* we're done */
159			}
160			}
161			objerror(r->ro, USER, "material not found");
162			}
163
164
165			raytexture(r, mod) /* get material modifiers */
166			RAY *r;
167			int mod;
168			{
169			static int depth = 0;
170			register OBJREC *m;
171			/* check for infinite loop */
172			if (depth++ >= MAXLOOP)
173			objerror(r->ro, USER, "modifier loop");
174			/* execute textures and patterns */
175			for ( ; mod != OVOID; mod = m->omod) {
176			m = objptr(mod);
177			if (!istexture(m->otype)) {
178			sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
179			error(USER, errmsg);
180			}
181			(*ofun[m->otype].funp)(m, r);
182			}
183			depth--; /* end here */
184			}
185
186
187			raymixture(r, fore, back, coef) /* mix modifiers */
188			register RAY *r;
189			OBJECT fore, back;
190			double coef;
191			{
192			FVECT curpert, forepert, backpert;
193			COLOR curpcol, forepcol, backpcol;
194			register int i;
195			/* clip coefficient */
196			if (coef > 1.0)
197			coef = 1.0;
198			else if (coef < 0.0)
199			coef = 0.0;
200			/* save current mods */
201			VCOPY(curpert, r->pert);
202			copycolor(curpcol, r->pcol);
203			/* compute new mods */
204			/* foreground */
205			r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
206			setcolor(r->pcol, 1.0, 1.0, 1.0);
207			if (fore != OVOID && coef > FTINY)
208			raytexture(r, fore);
209			VCOPY(forepert, r->pert);
210			copycolor(forepcol, r->pcol);
211			/* background */
212			r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
213			setcolor(r->pcol, 1.0, 1.0, 1.0);
214			if (back != OVOID && coef < 1.0-FTINY)
215			raytexture(r, back);
216			VCOPY(backpert, r->pert);
217			copycolor(backpcol, r->pcol);
218			/* sum perturbations */
219			for (i = 0; i < 3; i++)
220			r->pert[i] = curpert[i] + coef*forepert[i] +
221			(1.0-coef)*backpert[i];
222			/* multiply colors */
223			setcolor(r->pcol, coef*colval(forepcol,RED) +
224			(1.0-coef)*colval(backpcol,RED),
225			coef*colval(forepcol,GRN) +
226			(1.0-coef)*colval(backpcol,GRN),
227			coef*colval(forepcol,BLU) +
228			(1.0-coef)*colval(backpcol,BLU));
229			multcolor(r->pcol, curpcol);
230			}
231
232
233			double
234			raynormal(norm, r) /* compute perturbed normal for ray */
235			FVECT norm;
236			register RAY *r;
237			{
238			double newdot;
239			register int i;
240
241			/* The perturbation is added to the surface normal to obtain
242			* the new normal. If the new normal would affect the surface
243			* orientation wrt. the ray, a correction is made. The method is
244			* still fraught with problems since reflected rays and similar
245			* directions calculated from the surface normal may spawn rays behind
246			* the surface. The only solution is to curb textures at high
247	greg	1.9	* incidence (namely, keep DOT(rdir,pert) < Rdot).
248	greg	1.1	*/
249
250			for (i = 0; i < 3; i++)
251			norm[i] = r->ron[i] + r->pert[i];
252
253			if (normalize(norm) == 0.0) {
254			objerror(r->ro, WARNING, "illegal normal perturbation");
255			VCOPY(norm, r->ron);
256			return(r->rod);
257			}
258			newdot = -DOT(norm, r->rdir);
259			if ((newdot > 0.0) != (r->rod > 0.0)) { /* fix orientation */
260			for (i = 0; i < 3; i++)
261			norm[i] += 2.0newdotr->rdir[i];
262			newdot = -newdot;
263			}
264			return(newdot);
265	greg	1.12	}
266
267
268			newrayxf(r) /* get new tranformation matrix for ray */
269			RAY *r;
270			{
271			static struct xfn {
272			struct xfn *next;
273			FULLXF xf;
274			} xfseed = { &xfseed }, *xflast = &xfseed;
275			register struct xfn *xp;
276			register RAY *rp;
277
278			/*
279			* Search for transform in circular list that
280			* has no associated ray in the tree.
281			*/
282			xp = xflast;
283			for (rp = r->parent; rp != NULL; rp = rp->parent)
284			if (rp->rox == &xp->xf) { /* xp in use */
285			xp = xp->next; /* move to next */
286			if (xp == xflast) { /* need new one */
287	greg	1.14	xp = (struct xfn *)bmalloc(sizeof(struct xfn));
288	greg	1.12	if (xp == NULL)
289			error(SYSTEM,
290			"out of memory in newrayxf");
291			/* insert in list */
292			xp->next = xflast->next;
293			xflast->next = xp;
294			break; /* we're done */
295			}
296			rp = r; /* start check over */
297			}
298			/* got it */
299			r->rox = &xp->xf;
300			xflast = xp;
301	greg	1.1	}
302
303
304			flipsurface(r) /* reverse surface orientation */
305			register RAY *r;
306			{
307			r->rod = -r->rod;
308			r->ron[0] = -r->ron[0];
309			r->ron[1] = -r->ron[1];
310			r->ron[2] = -r->ron[2];
311			r->pert[0] = -r->pert[0];
312			r->pert[1] = -r->pert[1];
313			r->pert[2] = -r->pert[2];
314			}
315
316
317			localhit(r, scene) /* check for hit in the octree */
318			register RAY *r;
319			register CUBE *scene;
320			{
321	greg	2.3	OBJECT cxset[MAXCSET+1]; /* set of checked objects */
322	greg	1.1	FVECT curpos; /* current cube position */
323	greg	1.11	int sflags; /* sign flags */
324	greg	1.1	double t, dt;
325			register int i;
326
327	greg	1.21	nrays++; /* increment trace counter */
328	greg	1.11	sflags = 0;
329	greg	1.1	for (i = 0; i < 3; i++) {
330			curpos[i] = r->rorg[i];
331			if (r->rdir[i] > FTINY)
332	greg	1.11	sflags \|= 1 << i;
333	greg	1.1	else if (r->rdir[i] < -FTINY)
334	greg	1.11	sflags \|= 0x10 << i;
335	greg	1.1	}
336	greg	1.17	if (sflags == 0)
337			error(CONSISTENCY, "zero ray direction in localhit");
338	greg	1.1	t = 0.0;
339			if (!incube(scene, curpos)) {
340			/* find distance to entry */
341			for (i = 0; i < 3; i++) {
342			/* plane in our direction */
343	greg	1.11	if (sflags & 1<<i)
344	greg	1.1	dt = scene->cuorg[i];
345	greg	1.11	else if (sflags & 0x10<<i)
346	greg	1.1	dt = scene->cuorg[i] + scene->cusize;
347			else
348			continue;
349			/* distance to the plane */
350			dt = (dt - r->rorg[i])/r->rdir[i];
351			if (dt > t)
352			t = dt; /* farthest face is the one */
353			}
354			t += FTINY; /* fudge to get inside cube */
355			/* advance position */
356			for (i = 0; i < 3; i++)
357			curpos[i] += r->rdir[i]*t;
358
359			if (!incube(scene, curpos)) /* non-intersecting ray */
360			return(0);
361			}
362	greg	2.3	cxset[0] = 0;
363			return(raymove(curpos, cxset, sflags, r, scene) == RAYHIT);
364	greg	1.1	}
365
366
367			static int
368	greg	2.3	raymove(pos, cxs, dirf, r, cu) /* check for hit as we move */
369			FVECT pos; /* current position, modified herein */
370			OBJECT cxs; / checked objects, modified by checkhit */
371	greg	1.11	int dirf; /* direction indicators to speed tests */
372	greg	1.1	register RAY *r;
373			register CUBE *cu;
374			{
375			int ax;
376			double dt, t;
377
378			if (istree(cu->cutree)) { /* recurse on subcubes */
379			CUBE cukid;
380	greg	1.11	register int br, sgn;
381	greg	1.1
382			cukid.cusize = cu->cusize * 0.5; /* find subcube */
383			VCOPY(cukid.cuorg, cu->cuorg);
384			br = 0;
385			if (pos[0] >= cukid.cuorg[0]+cukid.cusize) {
386			cukid.cuorg[0] += cukid.cusize;
387			br \|= 1;
388			}
389			if (pos[1] >= cukid.cuorg[1]+cukid.cusize) {
390			cukid.cuorg[1] += cukid.cusize;
391			br \|= 2;
392			}
393			if (pos[2] >= cukid.cuorg[2]+cukid.cusize) {
394			cukid.cuorg[2] += cukid.cusize;
395			br \|= 4;
396			}
397			for ( ; ; ) {
398			cukid.cutree = octkid(cu->cutree, br);
399	greg	2.3	if ((ax = raymove(pos,cxs,dirf,r,&cukid)) == RAYHIT)
400	greg	1.1	return(RAYHIT);
401			sgn = 1 << ax;
402	greg	1.11	if (sgn & dirf) /* positive axis? */
403	greg	1.1	if (sgn & br)
404			return(ax); /* overflow */
405			else {
406			cukid.cuorg[ax] += cukid.cusize;
407			br \|= sgn;
408			}
409	greg	1.11	else
410			if (sgn & br) {
411			cukid.cuorg[ax] -= cukid.cusize;
412			br &= ~sgn;
413			} else
414			return(ax); /* underflow */
415	greg	1.1	}
416			/NOTREACHED/
417			}
418	greg	2.3	if (isfull(cu->cutree) && checkhit(r, cu, cxs))
419	greg	1.1	return(RAYHIT);
420			/* advance to next cube */
421	greg	1.11	if (dirf&0x11) {
422			dt = dirf&1 ? cu->cuorg[0] + cu->cusize : cu->cuorg[0];
423	greg	1.1	t = (dt - pos[0])/r->rdir[0];
424			ax = 0;
425			} else
426			t = FHUGE;
427	greg	1.11	if (dirf&0x22) {
428			dt = dirf&2 ? cu->cuorg[1] + cu->cusize : cu->cuorg[1];
429	greg	1.1	dt = (dt - pos[1])/r->rdir[1];
430			if (dt < t) {
431			t = dt;
432			ax = 1;
433			}
434			}
435	greg	1.11	if (dirf&0x44) {
436			dt = dirf&4 ? cu->cuorg[2] + cu->cusize : cu->cuorg[2];
437	greg	1.1	dt = (dt - pos[2])/r->rdir[2];
438			if (dt < t) {
439			t = dt;
440			ax = 2;
441			}
442			}
443			pos[0] += r->rdir[0]*t;
444			pos[1] += r->rdir[1]*t;
445			pos[2] += r->rdir[2]*t;
446			return(ax);
447			}
448
449
450			static
451	greg	2.3	checkhit(r, cu, cxs) /* check for hit in full cube */
452	greg	1.1	register RAY *r;
453			CUBE *cu;
454	greg	2.3	OBJECT *cxs;
455	greg	1.1	{
456			OBJECT oset[MAXSET+1];
457			register OBJREC *o;
458			register int i;
459
460			objset(oset, cu->cutree);
461	greg	2.3	checkset(oset, cxs); /* eliminate double-checking */
462	greg	1.1	for (i = oset[0]; i > 0; i--) {
463			o = objptr(oset[i]);
464	greg	2.4	if (o->omod == OVOID && issurface(o->otype))
465			continue; /* ignore void surfaces */
466	greg	1.1	(*ofun[o->otype].funp)(o, r);
467			}
468			if (r->ro == NULL)
469			return(0); /* no scores yet */
470
471			return(incube(cu, r->rop)); /* hit OK if in current cube */
472	greg	2.2	}
473
474
475			static
476			checkset(os, cs) /* modify checked set and set to check */
477	greg	2.3	register OBJECT os; / os' = os - cs */
478			register OBJECT cs; / cs' = cs + os */
479	greg	2.2	{
480			OBJECT cset[MAXCSET+MAXSET+1];
481	greg	2.3	register int i, j;
482			int k;
483	greg	2.2	/* copy os in place, cset <- cs */
484			cset[0] = 0;
485			k = 0;
486			for (i = j = 1; i <= os[0]; i++) {
487			while (j <= cs[0] && cs[j] < os[i])
488			cset[++cset[0]] = cs[j++];
489			if (j > cs[0] \|\| os[i] != cs[j]) { /* object to check */
490			os[++k] = os[i];
491			cset[++cset[0]] = os[i];
492			}
493			}
494	greg	2.3	if (!(os[0] = k)) /* new "to check" set size */
495			return; /* special case */
496	greg	2.2	while (j <= cs[0]) /* get the rest of cs */
497			cset[++cset[0]] = cs[j++];
498	greg	2.3	if (cset[0] > MAXCSET) /* truncate "checked" set if nec. */
499	greg	2.2	cset[0] = MAXCSET;
500	greg	2.3	/* setcopy(cs, cset); / / copy cset back to cs */
501			os = cset;
502			for (i = os[0]; i-- >= 0; )
503			cs++ = os++;
504	greg	1.1	}