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? */

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)();

        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)) ||
                        r->ro->omod == OVOID)
                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]);
                (*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:	2.7
Committed:	Wed Jul 21 15:36:13 1993 UTC (30 years, 9 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.6:	+2 -3 lines
Log Message:	fixed handling of void surfaces, which didn't work for instances
#	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	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
95	greg	1.15	if (localhit(r, &thescene))
96	greg	1.8	raycont(r);
97	greg	1.15	else if (sourcehit(r))
98			rayshade(r, r->ro->omod);
99	greg	1.1
100			if (trace != NULL)
101			(trace)(r); / trace execution */
102			}
103
104
105	greg	1.8	raycont(r) /* check for clipped object and continue */
106			register RAY *r;
107			{
108	greg	2.7	if ((r->clipset != NULL && inset(r->clipset, r->ro->omod)) \|\|
109			r->ro->omod == OVOID)
110	greg	1.8	raytrans(r);
111			else
112			rayshade(r, r->ro->omod);
113			}
114
115
116	greg	1.1	raytrans(r) /* transmit ray as is */
117	greg	1.8	register RAY *r;
118	greg	1.1	{
119			RAY tr;
120
121			if (rayorigin(&tr, r, TRANS, 1.0) == 0) {
122			VCOPY(tr.rdir, r->rdir);
123			rayvalue(&tr);
124			copycolor(r->rcol, tr.rcol);
125	greg	1.10	r->rt = r->rot + tr.rt;
126	greg	1.1	}
127			}
128
129
130			rayshade(r, mod) /* shade ray r with material mod */
131			register RAY *r;
132			int mod;
133			{
134			static int depth = 0;
135			register OBJREC *m;
136			/* check for infinite loop */
137			if (depth++ >= MAXLOOP)
138	greg	1.4	objerror(r->ro, USER, "possible modifier loop");
139	greg	1.19	r->rt = r->rot; /* set effective ray length */
140	greg	1.1	for ( ; mod != OVOID; mod = m->omod) {
141			m = objptr(mod);
142	greg	1.4	/****** unnecessary test since modifier() is always called
143	greg	1.1	if (!ismodifier(m->otype)) {
144			sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
145			error(USER, errmsg);
146			}
147	greg	1.4	******/
148	greg	1.16	/* hack for irradiance calculation */
149			if (do_irrad && !(r->crtype & ~(PRIMARY\|TRANS))) {
150			if (irr_ignore(m->otype)) {
151			depth--;
152			raytrans(r);
153			return;
154			}
155	greg	1.18	if (!islight(m->otype))
156	greg	1.16	m = &Lamb;
157			}
158	greg	1.1	(ofun[m->otype].funp)(m, r); / execute function */
159			if (ismaterial(m->otype)) { /* materials call raytexture */
160			depth--;
161			return; /* we're done */
162			}
163			}
164			objerror(r->ro, USER, "material not found");
165			}
166
167
168			raytexture(r, mod) /* get material modifiers */
169			RAY *r;
170			int mod;
171			{
172			static int depth = 0;
173			register OBJREC *m;
174			/* check for infinite loop */
175			if (depth++ >= MAXLOOP)
176			objerror(r->ro, USER, "modifier loop");
177			/* execute textures and patterns */
178			for ( ; mod != OVOID; mod = m->omod) {
179			m = objptr(mod);
180			if (!istexture(m->otype)) {
181			sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
182			error(USER, errmsg);
183			}
184			(*ofun[m->otype].funp)(m, r);
185			}
186			depth--; /* end here */
187			}
188
189
190			raymixture(r, fore, back, coef) /* mix modifiers */
191			register RAY *r;
192			OBJECT fore, back;
193			double coef;
194			{
195			FVECT curpert, forepert, backpert;
196			COLOR curpcol, forepcol, backpcol;
197			register int i;
198			/* clip coefficient */
199			if (coef > 1.0)
200			coef = 1.0;
201			else if (coef < 0.0)
202			coef = 0.0;
203			/* save current mods */
204			VCOPY(curpert, r->pert);
205			copycolor(curpcol, r->pcol);
206			/* compute new mods */
207			/* foreground */
208			r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
209			setcolor(r->pcol, 1.0, 1.0, 1.0);
210			if (fore != OVOID && coef > FTINY)
211			raytexture(r, fore);
212			VCOPY(forepert, r->pert);
213			copycolor(forepcol, r->pcol);
214			/* background */
215			r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
216			setcolor(r->pcol, 1.0, 1.0, 1.0);
217			if (back != OVOID && coef < 1.0-FTINY)
218			raytexture(r, back);
219			VCOPY(backpert, r->pert);
220			copycolor(backpcol, r->pcol);
221			/* sum perturbations */
222			for (i = 0; i < 3; i++)
223			r->pert[i] = curpert[i] + coef*forepert[i] +
224			(1.0-coef)*backpert[i];
225			/* multiply colors */
226			setcolor(r->pcol, coef*colval(forepcol,RED) +
227			(1.0-coef)*colval(backpcol,RED),
228			coef*colval(forepcol,GRN) +
229			(1.0-coef)*colval(backpcol,GRN),
230			coef*colval(forepcol,BLU) +
231			(1.0-coef)*colval(backpcol,BLU));
232			multcolor(r->pcol, curpcol);
233			}
234
235
236			double
237			raynormal(norm, r) /* compute perturbed normal for ray */
238			FVECT norm;
239			register RAY *r;
240			{
241			double newdot;
242			register int i;
243
244			/* The perturbation is added to the surface normal to obtain
245			* the new normal. If the new normal would affect the surface
246			* orientation wrt. the ray, a correction is made. The method is
247			* still fraught with problems since reflected rays and similar
248			* directions calculated from the surface normal may spawn rays behind
249			* the surface. The only solution is to curb textures at high
250	greg	1.9	* incidence (namely, keep DOT(rdir,pert) < Rdot).
251	greg	1.1	*/
252
253			for (i = 0; i < 3; i++)
254			norm[i] = r->ron[i] + r->pert[i];
255
256			if (normalize(norm) == 0.0) {
257			objerror(r->ro, WARNING, "illegal normal perturbation");
258			VCOPY(norm, r->ron);
259			return(r->rod);
260			}
261			newdot = -DOT(norm, r->rdir);
262			if ((newdot > 0.0) != (r->rod > 0.0)) { /* fix orientation */
263			for (i = 0; i < 3; i++)
264			norm[i] += 2.0newdotr->rdir[i];
265			newdot = -newdot;
266			}
267			return(newdot);
268	greg	1.12	}
269
270
271			newrayxf(r) /* get new tranformation matrix for ray */
272			RAY *r;
273			{
274			static struct xfn {
275			struct xfn *next;
276			FULLXF xf;
277			} xfseed = { &xfseed }, *xflast = &xfseed;
278			register struct xfn *xp;
279			register RAY *rp;
280
281			/*
282			* Search for transform in circular list that
283			* has no associated ray in the tree.
284			*/
285			xp = xflast;
286			for (rp = r->parent; rp != NULL; rp = rp->parent)
287			if (rp->rox == &xp->xf) { /* xp in use */
288			xp = xp->next; /* move to next */
289			if (xp == xflast) { /* need new one */
290	greg	1.14	xp = (struct xfn *)bmalloc(sizeof(struct xfn));
291	greg	1.12	if (xp == NULL)
292			error(SYSTEM,
293			"out of memory in newrayxf");
294			/* insert in list */
295			xp->next = xflast->next;
296			xflast->next = xp;
297			break; /* we're done */
298			}
299			rp = r; /* start check over */
300			}
301			/* got it */
302			r->rox = &xp->xf;
303			xflast = xp;
304	greg	1.1	}
305
306
307			flipsurface(r) /* reverse surface orientation */
308			register RAY *r;
309			{
310			r->rod = -r->rod;
311			r->ron[0] = -r->ron[0];
312			r->ron[1] = -r->ron[1];
313			r->ron[2] = -r->ron[2];
314			r->pert[0] = -r->pert[0];
315			r->pert[1] = -r->pert[1];
316			r->pert[2] = -r->pert[2];
317			}
318
319
320			localhit(r, scene) /* check for hit in the octree */
321			register RAY *r;
322			register CUBE *scene;
323			{
324	greg	2.3	OBJECT cxset[MAXCSET+1]; /* set of checked objects */
325	greg	1.1	FVECT curpos; /* current cube position */
326	greg	1.11	int sflags; /* sign flags */
327	greg	1.1	double t, dt;
328			register int i;
329
330	greg	1.21	nrays++; /* increment trace counter */
331	greg	1.11	sflags = 0;
332	greg	1.1	for (i = 0; i < 3; i++) {
333			curpos[i] = r->rorg[i];
334			if (r->rdir[i] > FTINY)
335	greg	1.11	sflags \|= 1 << i;
336	greg	1.1	else if (r->rdir[i] < -FTINY)
337	greg	1.11	sflags \|= 0x10 << i;
338	greg	1.1	}
339	greg	1.17	if (sflags == 0)
340			error(CONSISTENCY, "zero ray direction in localhit");
341	greg	1.1	t = 0.0;
342			if (!incube(scene, curpos)) {
343			/* find distance to entry */
344			for (i = 0; i < 3; i++) {
345			/* plane in our direction */
346	greg	1.11	if (sflags & 1<<i)
347	greg	1.1	dt = scene->cuorg[i];
348	greg	1.11	else if (sflags & 0x10<<i)
349	greg	1.1	dt = scene->cuorg[i] + scene->cusize;
350			else
351			continue;
352			/* distance to the plane */
353			dt = (dt - r->rorg[i])/r->rdir[i];
354			if (dt > t)
355			t = dt; /* farthest face is the one */
356			}
357			t += FTINY; /* fudge to get inside cube */
358			/* advance position */
359			for (i = 0; i < 3; i++)
360			curpos[i] += r->rdir[i]*t;
361
362			if (!incube(scene, curpos)) /* non-intersecting ray */
363			return(0);
364			}
365	greg	2.3	cxset[0] = 0;
366			return(raymove(curpos, cxset, sflags, r, scene) == RAYHIT);
367	greg	1.1	}
368
369
370			static int
371	greg	2.3	raymove(pos, cxs, dirf, r, cu) /* check for hit as we move */
372			FVECT pos; /* current position, modified herein */
373			OBJECT cxs; / checked objects, modified by checkhit */
374	greg	1.11	int dirf; /* direction indicators to speed tests */
375	greg	1.1	register RAY *r;
376			register CUBE *cu;
377			{
378			int ax;
379			double dt, t;
380
381			if (istree(cu->cutree)) { /* recurse on subcubes */
382			CUBE cukid;
383	greg	1.11	register int br, sgn;
384	greg	1.1
385			cukid.cusize = cu->cusize * 0.5; /* find subcube */
386			VCOPY(cukid.cuorg, cu->cuorg);
387			br = 0;
388			if (pos[0] >= cukid.cuorg[0]+cukid.cusize) {
389			cukid.cuorg[0] += cukid.cusize;
390			br \|= 1;
391			}
392			if (pos[1] >= cukid.cuorg[1]+cukid.cusize) {
393			cukid.cuorg[1] += cukid.cusize;
394			br \|= 2;
395			}
396			if (pos[2] >= cukid.cuorg[2]+cukid.cusize) {
397			cukid.cuorg[2] += cukid.cusize;
398			br \|= 4;
399			}
400			for ( ; ; ) {
401			cukid.cutree = octkid(cu->cutree, br);
402	greg	2.3	if ((ax = raymove(pos,cxs,dirf,r,&cukid)) == RAYHIT)
403	greg	1.1	return(RAYHIT);
404			sgn = 1 << ax;
405	greg	1.11	if (sgn & dirf) /* positive axis? */
406	greg	1.1	if (sgn & br)
407			return(ax); /* overflow */
408			else {
409			cukid.cuorg[ax] += cukid.cusize;
410			br \|= sgn;
411			}
412	greg	1.11	else
413			if (sgn & br) {
414			cukid.cuorg[ax] -= cukid.cusize;
415			br &= ~sgn;
416			} else
417			return(ax); /* underflow */
418	greg	1.1	}
419			/NOTREACHED/
420			}
421	greg	2.3	if (isfull(cu->cutree) && checkhit(r, cu, cxs))
422	greg	1.1	return(RAYHIT);
423			/* advance to next cube */
424	greg	1.11	if (dirf&0x11) {
425			dt = dirf&1 ? cu->cuorg[0] + cu->cusize : cu->cuorg[0];
426	greg	1.1	t = (dt - pos[0])/r->rdir[0];
427			ax = 0;
428			} else
429			t = FHUGE;
430	greg	1.11	if (dirf&0x22) {
431			dt = dirf&2 ? cu->cuorg[1] + cu->cusize : cu->cuorg[1];
432	greg	1.1	dt = (dt - pos[1])/r->rdir[1];
433			if (dt < t) {
434			t = dt;
435			ax = 1;
436			}
437			}
438	greg	1.11	if (dirf&0x44) {
439			dt = dirf&4 ? cu->cuorg[2] + cu->cusize : cu->cuorg[2];
440	greg	1.1	dt = (dt - pos[2])/r->rdir[2];
441			if (dt < t) {
442			t = dt;
443			ax = 2;
444			}
445			}
446			pos[0] += r->rdir[0]*t;
447			pos[1] += r->rdir[1]*t;
448			pos[2] += r->rdir[2]*t;
449			return(ax);
450			}
451
452
453			static
454	greg	2.3	checkhit(r, cu, cxs) /* check for hit in full cube */
455	greg	1.1	register RAY *r;
456			CUBE *cu;
457	greg	2.3	OBJECT *cxs;
458	greg	1.1	{
459			OBJECT oset[MAXSET+1];
460			register OBJREC *o;
461			register int i;
462
463			objset(oset, cu->cutree);
464	greg	2.3	checkset(oset, cxs); /* eliminate double-checking */
465	greg	1.1	for (i = oset[0]; i > 0; i--) {
466			o = objptr(oset[i]);
467			(*ofun[o->otype].funp)(o, r);
468			}
469			if (r->ro == NULL)
470			return(0); /* no scores yet */
471
472			return(incube(cu, r->rop)); /* hit OK if in current cube */
473	greg	2.2	}
474
475
476			static
477			checkset(os, cs) /* modify checked set and set to check */
478	greg	2.3	register OBJECT os; / os' = os - cs */
479			register OBJECT cs; / cs' = cs + os */
480	greg	2.2	{
481			OBJECT cset[MAXCSET+MAXSET+1];
482	greg	2.3	register int i, j;
483			int k;
484	greg	2.2	/* copy os in place, cset <- cs */
485			cset[0] = 0;
486			k = 0;
487			for (i = j = 1; i <= os[0]; i++) {
488			while (j <= cs[0] && cs[j] < os[i])
489			cset[++cset[0]] = cs[j++];
490			if (j > cs[0] \|\| os[i] != cs[j]) { /* object to check */
491			os[++k] = os[i];
492			cset[++cset[0]] = os[i];
493			}
494			}
495	greg	2.3	if (!(os[0] = k)) /* new "to check" set size */
496			return; /* special case */
497	greg	2.2	while (j <= cs[0]) /* get the rest of cs */
498			cset[++cset[0]] = cs[j++];
499	greg	2.3	if (cset[0] > MAXCSET) /* truncate "checked" set if nec. */
500	greg	2.2	cset[0] = MAXCSET;
501	greg	2.3	/* setcopy(cs, cset); / / copy cset back to cs */
502			os = cset;
503			for (i = os[0]; i-- >= 0; )
504			cs++ = os++;
505	greg	1.1	}