src/rt/raytrace.c

/* Copyright (c) 1994 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? */

unsigned long  raynum = 0;              /* next unique ray number */
unsigned long  nrays = 0;               /* 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 */

static int  raymove(), checkset(), checkhit();

#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)();
        int  gotmat;

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

        if (r->ro != NULL && !gotmat)
                objerror(r->ro, USER, "material not found");

        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)) ||
                        r->ro->omod == OVOID) {
                raytrans(r);
                return(1);
        }
        return(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;
        int  gotmat;
        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 (gotmat = 0; !gotmat && 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(1);
                        }
                        if (!islight(m->otype))
                                m = &Lamb;
                }
                                        /* materials call raytexture */
                gotmat = (*ofun[m->otype].funp)(m, r);
        }
        depth--;
        return(gotmat);
}


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);
                /****** unnecessary test since modifier() is always called
                if (!ismodifier(m->otype)) {
                        sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
                        error(USER, errmsg);
                }
                ******/
                if ((*ofun[m->otype].funp)(m, r))
                        objerror(r->ro, USER, "conflicting materials");
        }
        depth--;                        /* end here */
}


raymixture(r, fore, back, coef)         /* mix modifiers */
register RAY  *r;
OBJECT  fore, back;
double  coef;
{
        RAY  fr, br;
        int  foremat, backmat;
        register int  i;
                                        /* clip coefficient */
        if (coef > 1.0)
                coef = 1.0;
        else if (coef < 0.0)
                coef = 0.0;
                                        /* compute foreground and background */
        foremat = backmat = -1;
                                        /* foreground */
        copystruct(&fr, r);
        if (fore != OVOID && coef > FTINY)
                foremat = rayshade(&fr, fore);
                                        /* background */
        copystruct(&br, r);
        if (back != OVOID && coef < 1.0-FTINY)
                backmat = rayshade(&br, back);
                                        /* check */
        if (foremat < 0)
                if (backmat < 0)
                        foremat = backmat = 0;
                else
                        foremat = backmat;
        else if (backmat < 0)
                backmat = foremat;
        if ((foremat==0) != (backmat==0))
                objerror(r->ro, USER, "mixing material with non-material");
                                        /* mix perturbations */
        for (i = 0; i < 3; i++)
                r->pert[i] = coef*fr.pert[i] + (1.0-coef)*br.pert[i];
                                        /* mix pattern colors */
        scalecolor(fr.pcol, coef);
        scalecolor(br.pcol, 1.0-coef);
        copycolor(r->pcol, fr.pcol);
        addcolor(r->pcol, br.pcol);
                                        /* mix returned ray values */
        if (foremat) {
                scalecolor(fr.rcol, coef);
                scalecolor(br.rcol, 1.0-coef);
                copycolor(r->rcol, fr.rcol);
                addcolor(r->rcol, br.rcol);
                r->rt = bright(fr.rcol) > bright(br.rcol) ? fr.rt : br.rt;
        }
                                        /* return value tells if material */
        return(foremat);
}


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] > 1e-7)
                        sflags |= 1 << i;
                else if (r->rdir[i] < -1e-7)
                        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]);
                (*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:	2.15
Committed:	Mon Feb 28 08:54:02 1994 UTC (30 years, 2 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.14:	+1 -1 lines
Log Message:	added missing value for return statement in rayshade()
#	User	Rev	Content
1	greg	2.9	/* Copyright (c) 1994 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	2.6	unsigned long raynum = 0; /* next unique ray number */
29			unsigned long nrays = 0; /* 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	2.5	static int raymove(), checkset(), checkhit();
38
39	greg	1.6	#define MAXLOOP 128 /* modifier loop detection */
40	greg	1.1
41			#define RAYHIT (-1) /* return value for intercepted ray */
42
43
44			rayorigin(r, ro, rt, rw) /* start new ray from old one */
45			register RAY r, ro;
46			int rt;
47			double rw;
48			{
49			if ((r->parent = ro) == NULL) { /* primary ray */
50			r->rlvl = 0;
51			r->rweight = rw;
52			r->crtype = r->rtype = rt;
53			r->rsrc = -1;
54			r->clipset = NULL;
55	greg	1.21	r->revf = raytrace;
56	greg	1.1	} else { /* spawned ray */
57			r->rlvl = ro->rlvl;
58			if (rt & RAYREFL) {
59			r->rlvl++;
60			r->rsrc = -1;
61			r->clipset = ro->clipset;
62			} else {
63			r->rsrc = ro->rsrc;
64			r->clipset = ro->newcset;
65			}
66	greg	1.21	r->revf = ro->revf;
67	greg	1.1	r->rweight = ro->rweight * rw;
68			r->crtype = ro->crtype \| (r->rtype = rt);
69			VCOPY(r->rorg, ro->rop);
70			}
71	greg	1.22	rayclear(r);
72			return(r->rlvl <= maxdepth && r->rweight >= minweight ? 0 : -1);
73			}
74
75
76			rayclear(r) /* clear a ray for (re)evaluation */
77			register RAY *r;
78			{
79	greg	1.20	r->rno = raynum++;
80	greg	1.1	r->newcset = r->clipset;
81			r->ro = NULL;
82			r->rot = FHUGE;
83			r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
84			setcolor(r->pcol, 1.0, 1.0, 1.0);
85			setcolor(r->rcol, 0.0, 0.0, 0.0);
86	greg	1.10	r->rt = 0.0;
87	greg	1.1	}
88
89
90	greg	1.21	raytrace(r) /* trace a ray and compute its value */
91	greg	1.8	RAY *r;
92	greg	1.1	{
93			extern int (*trace)();
94	greg	2.9	int gotmat;
95	greg	1.1
96	greg	1.15	if (localhit(r, &thescene))
97	greg	2.9	gotmat = raycont(r);
98	greg	1.15	else if (sourcehit(r))
99	greg	2.9	gotmat = rayshade(r, r->ro->omod);
100	greg	1.1
101	greg	2.14	if (r->ro != NULL && !gotmat)
102	greg	2.9	objerror(r->ro, USER, "material not found");
103
104	greg	1.1	if (trace != NULL)
105			(trace)(r); / trace execution */
106			}
107
108
109	greg	1.8	raycont(r) /* check for clipped object and continue */
110			register RAY *r;
111			{
112	greg	2.7	if ((r->clipset != NULL && inset(r->clipset, r->ro->omod)) \|\|
113	greg	2.9	r->ro->omod == OVOID) {
114	greg	1.8	raytrans(r);
115	greg	2.9	return(1);
116			}
117			return(rayshade(r, r->ro->omod));
118	greg	1.8	}
119
120
121	greg	1.1	raytrans(r) /* transmit ray as is */
122	greg	1.8	register RAY *r;
123	greg	1.1	{
124			RAY tr;
125
126			if (rayorigin(&tr, r, TRANS, 1.0) == 0) {
127			VCOPY(tr.rdir, r->rdir);
128			rayvalue(&tr);
129			copycolor(r->rcol, tr.rcol);
130	greg	1.10	r->rt = r->rot + tr.rt;
131	greg	1.1	}
132			}
133
134
135			rayshade(r, mod) /* shade ray r with material mod */
136			register RAY *r;
137			int mod;
138			{
139			static int depth = 0;
140	greg	2.9	int gotmat;
141	greg	1.1	register OBJREC *m;
142			/* check for infinite loop */
143			if (depth++ >= MAXLOOP)
144	greg	1.4	objerror(r->ro, USER, "possible modifier loop");
145	greg	1.19	r->rt = r->rot; /* set effective ray length */
146	greg	2.9	for (gotmat = 0; !gotmat && mod != OVOID; mod = m->omod) {
147	greg	1.1	m = objptr(mod);
148	greg	1.4	/****** unnecessary test since modifier() is always called
149	greg	1.1	if (!ismodifier(m->otype)) {
150			sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
151			error(USER, errmsg);
152			}
153	greg	1.4	******/
154	greg	1.16	/* hack for irradiance calculation */
155			if (do_irrad && !(r->crtype & ~(PRIMARY\|TRANS))) {
156			if (irr_ignore(m->otype)) {
157			depth--;
158			raytrans(r);
159	greg	2.15	return(1);
160	greg	1.16	}
161	greg	1.18	if (!islight(m->otype))
162	greg	1.16	m = &Lamb;
163			}
164	greg	2.9	/* materials call raytexture */
165			gotmat = (*ofun[m->otype].funp)(m, r);
166	greg	1.1	}
167	greg	2.9	depth--;
168			return(gotmat);
169	greg	1.1	}
170
171
172			raytexture(r, mod) /* get material modifiers */
173			RAY *r;
174			int mod;
175			{
176			static int depth = 0;
177			register OBJREC *m;
178			/* check for infinite loop */
179			if (depth++ >= MAXLOOP)
180			objerror(r->ro, USER, "modifier loop");
181			/* execute textures and patterns */
182			for ( ; mod != OVOID; mod = m->omod) {
183			m = objptr(mod);
184	greg	2.9	/****** unnecessary test since modifier() is always called
185			if (!ismodifier(m->otype)) {
186	greg	1.1	sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
187			error(USER, errmsg);
188			}
189	greg	2.9	******/
190			if ((*ofun[m->otype].funp)(m, r))
191	greg	2.10	objerror(r->ro, USER, "conflicting materials");
192	greg	1.1	}
193			depth--; /* end here */
194			}
195
196
197			raymixture(r, fore, back, coef) /* mix modifiers */
198			register RAY *r;
199			OBJECT fore, back;
200			double coef;
201			{
202	greg	2.9	RAY fr, br;
203			int foremat, backmat;
204	greg	1.1	register int i;
205			/* clip coefficient */
206			if (coef > 1.0)
207			coef = 1.0;
208			else if (coef < 0.0)
209			coef = 0.0;
210	greg	2.13	/* compute foreground and background */
211			foremat = backmat = -1;
212	greg	2.9	/* foreground */
213			copystruct(&fr, r);
214	greg	1.1	if (fore != OVOID && coef > FTINY)
215	greg	2.9	foremat = rayshade(&fr, fore);
216			/* background */
217			copystruct(&br, r);
218	greg	1.1	if (back != OVOID && coef < 1.0-FTINY)
219	greg	2.9	backmat = rayshade(&br, back);
220	greg	2.13	/* check */
221			if (foremat < 0)
222			if (backmat < 0)
223			foremat = backmat = 0;
224			else
225			foremat = backmat;
226			else if (backmat < 0)
227	greg	2.9	backmat = foremat;
228	greg	2.12	if ((foremat==0) != (backmat==0))
229	greg	2.10	objerror(r->ro, USER, "mixing material with non-material");
230	greg	2.12	/* mix perturbations */
231	greg	1.1	for (i = 0; i < 3; i++)
232	greg	2.12	r->pert[i] = coeffr.pert[i] + (1.0-coef)br.pert[i];
233			/* mix pattern colors */
234	greg	2.9	scalecolor(fr.pcol, coef);
235			scalecolor(br.pcol, 1.0-coef);
236	greg	2.12	copycolor(r->pcol, fr.pcol);
237			addcolor(r->pcol, br.pcol);
238			/* mix returned ray values */
239			if (foremat) {
240			scalecolor(fr.rcol, coef);
241			scalecolor(br.rcol, 1.0-coef);
242			copycolor(r->rcol, fr.rcol);
243			addcolor(r->rcol, br.rcol);
244	greg	2.10	r->rt = bright(fr.rcol) > bright(br.rcol) ? fr.rt : br.rt;
245	greg	2.12	}
246	greg	2.9	/* return value tells if material */
247			return(foremat);
248	greg	1.1	}
249
250
251			double
252			raynormal(norm, r) /* compute perturbed normal for ray */
253			FVECT norm;
254			register RAY *r;
255			{
256			double newdot;
257			register int i;
258
259			/* The perturbation is added to the surface normal to obtain
260			* the new normal. If the new normal would affect the surface
261			* orientation wrt. the ray, a correction is made. The method is
262			* still fraught with problems since reflected rays and similar
263			* directions calculated from the surface normal may spawn rays behind
264			* the surface. The only solution is to curb textures at high
265	greg	1.9	* incidence (namely, keep DOT(rdir,pert) < Rdot).
266	greg	1.1	*/
267
268			for (i = 0; i < 3; i++)
269			norm[i] = r->ron[i] + r->pert[i];
270
271			if (normalize(norm) == 0.0) {
272			objerror(r->ro, WARNING, "illegal normal perturbation");
273			VCOPY(norm, r->ron);
274			return(r->rod);
275			}
276			newdot = -DOT(norm, r->rdir);
277			if ((newdot > 0.0) != (r->rod > 0.0)) { /* fix orientation */
278			for (i = 0; i < 3; i++)
279			norm[i] += 2.0newdotr->rdir[i];
280			newdot = -newdot;
281			}
282			return(newdot);
283	greg	1.12	}
284
285
286			newrayxf(r) /* get new tranformation matrix for ray */
287			RAY *r;
288			{
289			static struct xfn {
290			struct xfn *next;
291			FULLXF xf;
292			} xfseed = { &xfseed }, *xflast = &xfseed;
293			register struct xfn *xp;
294			register RAY *rp;
295
296			/*
297			* Search for transform in circular list that
298			* has no associated ray in the tree.
299			*/
300			xp = xflast;
301			for (rp = r->parent; rp != NULL; rp = rp->parent)
302			if (rp->rox == &xp->xf) { /* xp in use */
303			xp = xp->next; /* move to next */
304			if (xp == xflast) { /* need new one */
305	greg	1.14	xp = (struct xfn *)bmalloc(sizeof(struct xfn));
306	greg	1.12	if (xp == NULL)
307			error(SYSTEM,
308			"out of memory in newrayxf");
309			/* insert in list */
310			xp->next = xflast->next;
311			xflast->next = xp;
312			break; /* we're done */
313			}
314			rp = r; /* start check over */
315			}
316			/* got it */
317			r->rox = &xp->xf;
318			xflast = xp;
319	greg	1.1	}
320
321
322			flipsurface(r) /* reverse surface orientation */
323			register RAY *r;
324			{
325			r->rod = -r->rod;
326			r->ron[0] = -r->ron[0];
327			r->ron[1] = -r->ron[1];
328			r->ron[2] = -r->ron[2];
329			r->pert[0] = -r->pert[0];
330			r->pert[1] = -r->pert[1];
331			r->pert[2] = -r->pert[2];
332			}
333
334
335			localhit(r, scene) /* check for hit in the octree */
336			register RAY *r;
337			register CUBE *scene;
338			{
339	greg	2.3	OBJECT cxset[MAXCSET+1]; /* set of checked objects */
340	greg	1.1	FVECT curpos; /* current cube position */
341	greg	1.11	int sflags; /* sign flags */
342	greg	1.1	double t, dt;
343			register int i;
344
345	greg	1.21	nrays++; /* increment trace counter */
346	greg	1.11	sflags = 0;
347	greg	1.1	for (i = 0; i < 3; i++) {
348			curpos[i] = r->rorg[i];
349	greg	2.8	if (r->rdir[i] > 1e-7)
350	greg	1.11	sflags \|= 1 << i;
351	greg	2.8	else if (r->rdir[i] < -1e-7)
352	greg	1.11	sflags \|= 0x10 << i;
353	greg	1.1	}
354	greg	1.17	if (sflags == 0)
355			error(CONSISTENCY, "zero ray direction in localhit");
356	greg	1.1	t = 0.0;
357			if (!incube(scene, curpos)) {
358			/* find distance to entry */
359			for (i = 0; i < 3; i++) {
360			/* plane in our direction */
361	greg	1.11	if (sflags & 1<<i)
362	greg	1.1	dt = scene->cuorg[i];
363	greg	1.11	else if (sflags & 0x10<<i)
364	greg	1.1	dt = scene->cuorg[i] + scene->cusize;
365			else
366			continue;
367			/* distance to the plane */
368			dt = (dt - r->rorg[i])/r->rdir[i];
369			if (dt > t)
370			t = dt; /* farthest face is the one */
371			}
372			t += FTINY; /* fudge to get inside cube */
373			/* advance position */
374			for (i = 0; i < 3; i++)
375			curpos[i] += r->rdir[i]*t;
376
377			if (!incube(scene, curpos)) /* non-intersecting ray */
378			return(0);
379			}
380	greg	2.3	cxset[0] = 0;
381			return(raymove(curpos, cxset, sflags, r, scene) == RAYHIT);
382	greg	1.1	}
383
384
385			static int
386	greg	2.3	raymove(pos, cxs, dirf, r, cu) /* check for hit as we move */
387			FVECT pos; /* current position, modified herein */
388			OBJECT cxs; / checked objects, modified by checkhit */
389	greg	1.11	int dirf; /* direction indicators to speed tests */
390	greg	1.1	register RAY *r;
391			register CUBE *cu;
392			{
393			int ax;
394			double dt, t;
395
396			if (istree(cu->cutree)) { /* recurse on subcubes */
397			CUBE cukid;
398	greg	1.11	register int br, sgn;
399	greg	1.1
400			cukid.cusize = cu->cusize * 0.5; /* find subcube */
401			VCOPY(cukid.cuorg, cu->cuorg);
402			br = 0;
403			if (pos[0] >= cukid.cuorg[0]+cukid.cusize) {
404			cukid.cuorg[0] += cukid.cusize;
405			br \|= 1;
406			}
407			if (pos[1] >= cukid.cuorg[1]+cukid.cusize) {
408			cukid.cuorg[1] += cukid.cusize;
409			br \|= 2;
410			}
411			if (pos[2] >= cukid.cuorg[2]+cukid.cusize) {
412			cukid.cuorg[2] += cukid.cusize;
413			br \|= 4;
414			}
415			for ( ; ; ) {
416			cukid.cutree = octkid(cu->cutree, br);
417	greg	2.3	if ((ax = raymove(pos,cxs,dirf,r,&cukid)) == RAYHIT)
418	greg	1.1	return(RAYHIT);
419			sgn = 1 << ax;
420	greg	1.11	if (sgn & dirf) /* positive axis? */
421	greg	1.1	if (sgn & br)
422			return(ax); /* overflow */
423			else {
424			cukid.cuorg[ax] += cukid.cusize;
425			br \|= sgn;
426			}
427	greg	1.11	else
428			if (sgn & br) {
429			cukid.cuorg[ax] -= cukid.cusize;
430			br &= ~sgn;
431			} else
432			return(ax); /* underflow */
433	greg	1.1	}
434			/NOTREACHED/
435			}
436	greg	2.3	if (isfull(cu->cutree) && checkhit(r, cu, cxs))
437	greg	1.1	return(RAYHIT);
438			/* advance to next cube */
439	greg	1.11	if (dirf&0x11) {
440			dt = dirf&1 ? cu->cuorg[0] + cu->cusize : cu->cuorg[0];
441	greg	1.1	t = (dt - pos[0])/r->rdir[0];
442			ax = 0;
443			} else
444			t = FHUGE;
445	greg	1.11	if (dirf&0x22) {
446			dt = dirf&2 ? cu->cuorg[1] + cu->cusize : cu->cuorg[1];
447	greg	1.1	dt = (dt - pos[1])/r->rdir[1];
448			if (dt < t) {
449			t = dt;
450			ax = 1;
451			}
452			}
453	greg	1.11	if (dirf&0x44) {
454			dt = dirf&4 ? cu->cuorg[2] + cu->cusize : cu->cuorg[2];
455	greg	1.1	dt = (dt - pos[2])/r->rdir[2];
456			if (dt < t) {
457			t = dt;
458			ax = 2;
459			}
460			}
461			pos[0] += r->rdir[0]*t;
462			pos[1] += r->rdir[1]*t;
463			pos[2] += r->rdir[2]*t;
464			return(ax);
465			}
466
467
468			static
469	greg	2.3	checkhit(r, cu, cxs) /* check for hit in full cube */
470	greg	1.1	register RAY *r;
471			CUBE *cu;
472	greg	2.3	OBJECT *cxs;
473	greg	1.1	{
474			OBJECT oset[MAXSET+1];
475			register OBJREC *o;
476			register int i;
477
478			objset(oset, cu->cutree);
479	greg	2.3	checkset(oset, cxs); /* eliminate double-checking */
480	greg	1.1	for (i = oset[0]; i > 0; i--) {
481			o = objptr(oset[i]);
482			(*ofun[o->otype].funp)(o, r);
483			}
484			if (r->ro == NULL)
485			return(0); /* no scores yet */
486
487			return(incube(cu, r->rop)); /* hit OK if in current cube */
488	greg	2.2	}
489
490
491			static
492			checkset(os, cs) /* modify checked set and set to check */
493	greg	2.3	register OBJECT os; / os' = os - cs */
494			register OBJECT cs; / cs' = cs + os */
495	greg	2.2	{
496			OBJECT cset[MAXCSET+MAXSET+1];
497	greg	2.3	register int i, j;
498			int k;
499	greg	2.2	/* copy os in place, cset <- cs */
500			cset[0] = 0;
501			k = 0;
502			for (i = j = 1; i <= os[0]; i++) {
503			while (j <= cs[0] && cs[j] < os[i])
504			cset[++cset[0]] = cs[j++];
505			if (j > cs[0] \|\| os[i] != cs[j]) { /* object to check */
506			os[++k] = os[i];
507			cset[++cset[0]] = os[i];
508			}
509			}
510	greg	2.3	if (!(os[0] = k)) /* new "to check" set size */
511			return; /* special case */
512	greg	2.2	while (j <= cs[0]) /* get the rest of cs */
513			cset[++cset[0]] = cs[j++];
514	greg	2.3	if (cset[0] > MAXCSET) /* truncate "checked" set if nec. */
515	greg	2.2	cset[0] = MAXCSET;
516	greg	2.3	/* setcopy(cs, cset); / / copy cset back to cs */
517			os = cset;
518			for (i = os[0]; i-- >= 0; )
519			cs++ = os++;
520	greg	1.1	}