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 */

OBJREC  Aftplane;                       /* aft clipping plane object */

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);
                r->rmax = 0.0;
        }
        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 (r->ro == &Aftplane) {
                r->ro = NULL;
                r->rot = FHUGE;
        } 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);
                if (r->rmax > FTINY)
                        tr.rmax = r->rmax - r->rot;
                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");
                                        /* start off assuming nothing hit */
        if (r->rmax > FTINY) {          /* except aft plane if one */
                r->ro = &Aftplane;
                r->rot = r->rmax;
                for (i = 0; i < 3; i++)
                        r->rop[i] = r->rorg[i] + r->rot*r->rdir[i];
        }
                                        /* find global cube entrance point */
        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 */
                if (t >= r->rot)        /* clipped already */
                        return(0);
                                        /* 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 &&
                        r->ro != &Aftplane);
}


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)) {
                if (checkhit(r, cu, cxs))
                        return(RAYHIT);
        } else if (r->ro == &Aftplane && incube(cu, r->rop))
                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:	2.18
Committed:	Fri Jan 6 14:00:47 1995 UTC (29 years, 4 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.17:	+4 -1 lines
Log Message:	added test against aft plane in empty voxels
#	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	2.17	OBJREC Aftplane; /* aft clipping plane object */
38	greg	2.16
39	greg	2.5	static int raymove(), checkset(), checkhit();
40
41	greg	1.6	#define MAXLOOP 128 /* modifier loop detection */
42	greg	1.1
43			#define RAYHIT (-1) /* return value for intercepted ray */
44
45
46			rayorigin(r, ro, rt, rw) /* start new ray from old one */
47			register RAY r, ro;
48			int rt;
49			double rw;
50			{
51			if ((r->parent = ro) == NULL) { /* primary ray */
52			r->rlvl = 0;
53			r->rweight = rw;
54			r->crtype = r->rtype = rt;
55			r->rsrc = -1;
56			r->clipset = NULL;
57	greg	1.21	r->revf = raytrace;
58	greg	1.1	} else { /* spawned ray */
59			r->rlvl = ro->rlvl;
60			if (rt & RAYREFL) {
61			r->rlvl++;
62			r->rsrc = -1;
63			r->clipset = ro->clipset;
64			} else {
65			r->rsrc = ro->rsrc;
66			r->clipset = ro->newcset;
67			}
68	greg	1.21	r->revf = ro->revf;
69	greg	1.1	r->rweight = ro->rweight * rw;
70			r->crtype = ro->crtype \| (r->rtype = rt);
71			VCOPY(r->rorg, ro->rop);
72	greg	2.16	r->rmax = 0.0;
73	greg	1.1	}
74	greg	1.22	rayclear(r);
75			return(r->rlvl <= maxdepth && r->rweight >= minweight ? 0 : -1);
76			}
77
78
79			rayclear(r) /* clear a ray for (re)evaluation */
80			register RAY *r;
81			{
82	greg	1.20	r->rno = raynum++;
83	greg	1.1	r->newcset = r->clipset;
84	greg	2.17	r->ro = NULL;
85			r->rot = FHUGE;
86	greg	1.1	r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
87			setcolor(r->pcol, 1.0, 1.0, 1.0);
88			setcolor(r->rcol, 0.0, 0.0, 0.0);
89	greg	1.10	r->rt = 0.0;
90	greg	1.1	}
91
92
93	greg	1.21	raytrace(r) /* trace a ray and compute its value */
94	greg	1.8	RAY *r;
95	greg	1.1	{
96			extern int (*trace)();
97	greg	2.9	int gotmat;
98	greg	1.1
99	greg	1.15	if (localhit(r, &thescene))
100	greg	2.9	gotmat = raycont(r);
101	greg	2.16	else if (r->ro == &Aftplane) {
102			r->ro = NULL;
103			r->rot = FHUGE;
104			} else if (sourcehit(r))
105	greg	2.9	gotmat = rayshade(r, r->ro->omod);
106	greg	1.1
107	greg	2.14	if (r->ro != NULL && !gotmat)
108	greg	2.9	objerror(r->ro, USER, "material not found");
109
110	greg	1.1	if (trace != NULL)
111			(trace)(r); / trace execution */
112			}
113
114
115	greg	1.8	raycont(r) /* check for clipped object and continue */
116			register RAY *r;
117			{
118	greg	2.7	if ((r->clipset != NULL && inset(r->clipset, r->ro->omod)) \|\|
119	greg	2.9	r->ro->omod == OVOID) {
120	greg	1.8	raytrans(r);
121	greg	2.9	return(1);
122			}
123			return(rayshade(r, r->ro->omod));
124	greg	1.8	}
125
126
127	greg	1.1	raytrans(r) /* transmit ray as is */
128	greg	1.8	register RAY *r;
129	greg	1.1	{
130			RAY tr;
131
132			if (rayorigin(&tr, r, TRANS, 1.0) == 0) {
133			VCOPY(tr.rdir, r->rdir);
134	greg	2.17	if (r->rmax > FTINY)
135			tr.rmax = r->rmax - r->rot;
136	greg	1.1	rayvalue(&tr);
137			copycolor(r->rcol, tr.rcol);
138	greg	1.10	r->rt = r->rot + tr.rt;
139	greg	1.1	}
140			}
141
142
143			rayshade(r, mod) /* shade ray r with material mod */
144			register RAY *r;
145			int mod;
146			{
147			static int depth = 0;
148	greg	2.9	int gotmat;
149	greg	1.1	register OBJREC *m;
150			/* check for infinite loop */
151			if (depth++ >= MAXLOOP)
152	greg	1.4	objerror(r->ro, USER, "possible modifier loop");
153	greg	1.19	r->rt = r->rot; /* set effective ray length */
154	greg	2.9	for (gotmat = 0; !gotmat && mod != OVOID; mod = m->omod) {
155	greg	1.1	m = objptr(mod);
156	greg	1.4	/****** unnecessary test since modifier() is always called
157	greg	1.1	if (!ismodifier(m->otype)) {
158			sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
159			error(USER, errmsg);
160			}
161	greg	1.4	******/
162	greg	1.16	/* hack for irradiance calculation */
163			if (do_irrad && !(r->crtype & ~(PRIMARY\|TRANS))) {
164			if (irr_ignore(m->otype)) {
165			depth--;
166			raytrans(r);
167	greg	2.15	return(1);
168	greg	1.16	}
169	greg	1.18	if (!islight(m->otype))
170	greg	1.16	m = &Lamb;
171			}
172	greg	2.9	/* materials call raytexture */
173			gotmat = (*ofun[m->otype].funp)(m, r);
174	greg	1.1	}
175	greg	2.9	depth--;
176			return(gotmat);
177	greg	1.1	}
178
179
180			raytexture(r, mod) /* get material modifiers */
181			RAY *r;
182			int mod;
183			{
184			static int depth = 0;
185			register OBJREC *m;
186			/* check for infinite loop */
187			if (depth++ >= MAXLOOP)
188			objerror(r->ro, USER, "modifier loop");
189			/* execute textures and patterns */
190			for ( ; mod != OVOID; mod = m->omod) {
191			m = objptr(mod);
192	greg	2.9	/****** unnecessary test since modifier() is always called
193			if (!ismodifier(m->otype)) {
194	greg	1.1	sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
195			error(USER, errmsg);
196			}
197	greg	2.9	******/
198			if ((*ofun[m->otype].funp)(m, r))
199	greg	2.10	objerror(r->ro, USER, "conflicting materials");
200	greg	1.1	}
201			depth--; /* end here */
202			}
203
204
205			raymixture(r, fore, back, coef) /* mix modifiers */
206			register RAY *r;
207			OBJECT fore, back;
208			double coef;
209			{
210	greg	2.9	RAY fr, br;
211			int foremat, backmat;
212	greg	1.1	register int i;
213			/* clip coefficient */
214			if (coef > 1.0)
215			coef = 1.0;
216			else if (coef < 0.0)
217			coef = 0.0;
218	greg	2.13	/* compute foreground and background */
219			foremat = backmat = -1;
220	greg	2.9	/* foreground */
221			copystruct(&fr, r);
222	greg	1.1	if (fore != OVOID && coef > FTINY)
223	greg	2.9	foremat = rayshade(&fr, fore);
224			/* background */
225			copystruct(&br, r);
226	greg	1.1	if (back != OVOID && coef < 1.0-FTINY)
227	greg	2.9	backmat = rayshade(&br, back);
228	greg	2.13	/* check */
229			if (foremat < 0)
230			if (backmat < 0)
231			foremat = backmat = 0;
232			else
233			foremat = backmat;
234			else if (backmat < 0)
235	greg	2.9	backmat = foremat;
236	greg	2.12	if ((foremat==0) != (backmat==0))
237	greg	2.10	objerror(r->ro, USER, "mixing material with non-material");
238	greg	2.12	/* mix perturbations */
239	greg	1.1	for (i = 0; i < 3; i++)
240	greg	2.12	r->pert[i] = coeffr.pert[i] + (1.0-coef)br.pert[i];
241			/* mix pattern colors */
242	greg	2.9	scalecolor(fr.pcol, coef);
243			scalecolor(br.pcol, 1.0-coef);
244	greg	2.12	copycolor(r->pcol, fr.pcol);
245			addcolor(r->pcol, br.pcol);
246			/* mix returned ray values */
247			if (foremat) {
248			scalecolor(fr.rcol, coef);
249			scalecolor(br.rcol, 1.0-coef);
250			copycolor(r->rcol, fr.rcol);
251			addcolor(r->rcol, br.rcol);
252	greg	2.10	r->rt = bright(fr.rcol) > bright(br.rcol) ? fr.rt : br.rt;
253	greg	2.12	}
254	greg	2.9	/* return value tells if material */
255			return(foremat);
256	greg	1.1	}
257
258
259			double
260			raynormal(norm, r) /* compute perturbed normal for ray */
261			FVECT norm;
262			register RAY *r;
263			{
264			double newdot;
265			register int i;
266
267			/* The perturbation is added to the surface normal to obtain
268			* the new normal. If the new normal would affect the surface
269			* orientation wrt. the ray, a correction is made. The method is
270			* still fraught with problems since reflected rays and similar
271			* directions calculated from the surface normal may spawn rays behind
272			* the surface. The only solution is to curb textures at high
273	greg	1.9	* incidence (namely, keep DOT(rdir,pert) < Rdot).
274	greg	1.1	*/
275
276			for (i = 0; i < 3; i++)
277			norm[i] = r->ron[i] + r->pert[i];
278
279			if (normalize(norm) == 0.0) {
280			objerror(r->ro, WARNING, "illegal normal perturbation");
281			VCOPY(norm, r->ron);
282			return(r->rod);
283			}
284			newdot = -DOT(norm, r->rdir);
285			if ((newdot > 0.0) != (r->rod > 0.0)) { /* fix orientation */
286			for (i = 0; i < 3; i++)
287			norm[i] += 2.0newdotr->rdir[i];
288			newdot = -newdot;
289			}
290			return(newdot);
291	greg	1.12	}
292
293
294			newrayxf(r) /* get new tranformation matrix for ray */
295			RAY *r;
296			{
297			static struct xfn {
298			struct xfn *next;
299			FULLXF xf;
300			} xfseed = { &xfseed }, *xflast = &xfseed;
301			register struct xfn *xp;
302			register RAY *rp;
303
304			/*
305			* Search for transform in circular list that
306			* has no associated ray in the tree.
307			*/
308			xp = xflast;
309			for (rp = r->parent; rp != NULL; rp = rp->parent)
310			if (rp->rox == &xp->xf) { /* xp in use */
311			xp = xp->next; /* move to next */
312			if (xp == xflast) { /* need new one */
313	greg	1.14	xp = (struct xfn *)bmalloc(sizeof(struct xfn));
314	greg	1.12	if (xp == NULL)
315			error(SYSTEM,
316			"out of memory in newrayxf");
317			/* insert in list */
318			xp->next = xflast->next;
319			xflast->next = xp;
320			break; /* we're done */
321			}
322			rp = r; /* start check over */
323			}
324			/* got it */
325			r->rox = &xp->xf;
326			xflast = xp;
327	greg	1.1	}
328
329
330			flipsurface(r) /* reverse surface orientation */
331			register RAY *r;
332			{
333			r->rod = -r->rod;
334			r->ron[0] = -r->ron[0];
335			r->ron[1] = -r->ron[1];
336			r->ron[2] = -r->ron[2];
337			r->pert[0] = -r->pert[0];
338			r->pert[1] = -r->pert[1];
339			r->pert[2] = -r->pert[2];
340			}
341
342
343			localhit(r, scene) /* check for hit in the octree */
344			register RAY *r;
345			register CUBE *scene;
346			{
347	greg	2.3	OBJECT cxset[MAXCSET+1]; /* set of checked objects */
348	greg	1.1	FVECT curpos; /* current cube position */
349	greg	1.11	int sflags; /* sign flags */
350	greg	1.1	double t, dt;
351			register int i;
352
353	greg	1.21	nrays++; /* increment trace counter */
354	greg	1.11	sflags = 0;
355	greg	1.1	for (i = 0; i < 3; i++) {
356			curpos[i] = r->rorg[i];
357	greg	2.8	if (r->rdir[i] > 1e-7)
358	greg	1.11	sflags \|= 1 << i;
359	greg	2.8	else if (r->rdir[i] < -1e-7)
360	greg	1.11	sflags \|= 0x10 << i;
361	greg	1.1	}
362	greg	1.17	if (sflags == 0)
363			error(CONSISTENCY, "zero ray direction in localhit");
364	greg	2.17	/* start off assuming nothing hit */
365			if (r->rmax > FTINY) { /* except aft plane if one */
366			r->ro = &Aftplane;
367			r->rot = r->rmax;
368			for (i = 0; i < 3; i++)
369			r->rop[i] = r->rorg[i] + r->rot*r->rdir[i];
370			}
371			/* find global cube entrance point */
372	greg	1.1	t = 0.0;
373			if (!incube(scene, curpos)) {
374			/* find distance to entry */
375			for (i = 0; i < 3; i++) {
376			/* plane in our direction */
377	greg	1.11	if (sflags & 1<<i)
378	greg	1.1	dt = scene->cuorg[i];
379	greg	1.11	else if (sflags & 0x10<<i)
380	greg	1.1	dt = scene->cuorg[i] + scene->cusize;
381			else
382			continue;
383			/* distance to the plane */
384			dt = (dt - r->rorg[i])/r->rdir[i];
385			if (dt > t)
386			t = dt; /* farthest face is the one */
387			}
388			t += FTINY; /* fudge to get inside cube */
389	greg	2.17	if (t >= r->rot) /* clipped already */
390			return(0);
391	greg	1.1	/* advance position */
392			for (i = 0; i < 3; i++)
393			curpos[i] += r->rdir[i]*t;
394
395			if (!incube(scene, curpos)) /* non-intersecting ray */
396			return(0);
397			}
398	greg	2.3	cxset[0] = 0;
399	greg	2.16	return(raymove(curpos, cxset, sflags, r, scene) == RAYHIT &&
400			r->ro != &Aftplane);
401	greg	1.1	}
402
403
404			static int
405	greg	2.3	raymove(pos, cxs, dirf, r, cu) /* check for hit as we move */
406			FVECT pos; /* current position, modified herein */
407			OBJECT cxs; / checked objects, modified by checkhit */
408	greg	1.11	int dirf; /* direction indicators to speed tests */
409	greg	1.1	register RAY *r;
410			register CUBE *cu;
411			{
412			int ax;
413			double dt, t;
414
415			if (istree(cu->cutree)) { /* recurse on subcubes */
416			CUBE cukid;
417	greg	1.11	register int br, sgn;
418	greg	1.1
419			cukid.cusize = cu->cusize * 0.5; /* find subcube */
420			VCOPY(cukid.cuorg, cu->cuorg);
421			br = 0;
422			if (pos[0] >= cukid.cuorg[0]+cukid.cusize) {
423			cukid.cuorg[0] += cukid.cusize;
424			br \|= 1;
425			}
426			if (pos[1] >= cukid.cuorg[1]+cukid.cusize) {
427			cukid.cuorg[1] += cukid.cusize;
428			br \|= 2;
429			}
430			if (pos[2] >= cukid.cuorg[2]+cukid.cusize) {
431			cukid.cuorg[2] += cukid.cusize;
432			br \|= 4;
433			}
434			for ( ; ; ) {
435			cukid.cutree = octkid(cu->cutree, br);
436	greg	2.3	if ((ax = raymove(pos,cxs,dirf,r,&cukid)) == RAYHIT)
437	greg	1.1	return(RAYHIT);
438			sgn = 1 << ax;
439	greg	1.11	if (sgn & dirf) /* positive axis? */
440	greg	1.1	if (sgn & br)
441			return(ax); /* overflow */
442			else {
443			cukid.cuorg[ax] += cukid.cusize;
444			br \|= sgn;
445			}
446	greg	1.11	else
447			if (sgn & br) {
448			cukid.cuorg[ax] -= cukid.cusize;
449			br &= ~sgn;
450			} else
451			return(ax); /* underflow */
452	greg	1.1	}
453			/NOTREACHED/
454			}
455	greg	2.18	if (isfull(cu->cutree)) {
456			if (checkhit(r, cu, cxs))
457			return(RAYHIT);
458			} else if (r->ro == &Aftplane && incube(cu, r->rop))
459	greg	1.1	return(RAYHIT);
460			/* advance to next cube */
461	greg	1.11	if (dirf&0x11) {
462			dt = dirf&1 ? cu->cuorg[0] + cu->cusize : cu->cuorg[0];
463	greg	1.1	t = (dt - pos[0])/r->rdir[0];
464			ax = 0;
465			} else
466			t = FHUGE;
467	greg	1.11	if (dirf&0x22) {
468			dt = dirf&2 ? cu->cuorg[1] + cu->cusize : cu->cuorg[1];
469	greg	1.1	dt = (dt - pos[1])/r->rdir[1];
470			if (dt < t) {
471			t = dt;
472			ax = 1;
473			}
474			}
475	greg	1.11	if (dirf&0x44) {
476			dt = dirf&4 ? cu->cuorg[2] + cu->cusize : cu->cuorg[2];
477	greg	1.1	dt = (dt - pos[2])/r->rdir[2];
478			if (dt < t) {
479			t = dt;
480			ax = 2;
481			}
482			}
483			pos[0] += r->rdir[0]*t;
484			pos[1] += r->rdir[1]*t;
485			pos[2] += r->rdir[2]*t;
486			return(ax);
487			}
488
489
490			static
491	greg	2.3	checkhit(r, cu, cxs) /* check for hit in full cube */
492	greg	1.1	register RAY *r;
493			CUBE *cu;
494	greg	2.3	OBJECT *cxs;
495	greg	1.1	{
496			OBJECT oset[MAXSET+1];
497			register OBJREC *o;
498			register int i;
499
500			objset(oset, cu->cutree);
501	greg	2.3	checkset(oset, cxs); /* eliminate double-checking */
502	greg	1.1	for (i = oset[0]; i > 0; i--) {
503			o = objptr(oset[i]);
504			(*ofun[o->otype].funp)(o, r);
505			}
506			if (r->ro == NULL)
507			return(0); /* no scores yet */
508
509			return(incube(cu, r->rop)); /* hit OK if in current cube */
510	greg	2.2	}
511
512
513			static
514			checkset(os, cs) /* modify checked set and set to check */
515	greg	2.3	register OBJECT os; / os' = os - cs */
516			register OBJECT cs; / cs' = cs + os */
517	greg	2.2	{
518			OBJECT cset[MAXCSET+MAXSET+1];
519	greg	2.3	register int i, j;
520			int k;
521	greg	2.2	/* copy os in place, cset <- cs */
522			cset[0] = 0;
523			k = 0;
524			for (i = j = 1; i <= os[0]; i++) {
525			while (j <= cs[0] && cs[j] < os[i])
526			cset[++cset[0]] = cs[j++];
527			if (j > cs[0] \|\| os[i] != cs[j]) { /* object to check */
528			os[++k] = os[i];
529			cset[++cset[0]] = os[i];
530			}
531			}
532	greg	2.3	if (!(os[0] = k)) /* new "to check" set size */
533			return; /* special case */
534	greg	2.2	while (j <= cs[0]) /* get the rest of cs */
535			cset[++cset[0]] = cs[j++];
536	greg	2.3	if (cset[0] > MAXCSET) /* truncate "checked" set if nec. */
537	greg	2.2	cset[0] = MAXCSET;
538	greg	2.3	/* setcopy(cs, cset); / / copy cset back to cs */
539			os = cset;
540			for (i = os[0]; i-- >= 0; )
541			cs++ = os++;
542	greg	1.1	}