src/rt/raytrace.c

#ifndef lint
static const char RCSid[] = "$Id: raytrace.c,v 2.43 2003/09/09 03:28:43 greg Exp $";
#endif
/*
 *  raytrace.c - routines for tracing and shading rays.
 *
 *  External symbols declared in ray.h
 */

#include "copyright.h"

#include  "ray.h"

#include  "otypes.h"

#include  "otspecial.h"

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

unsigned long  raynum = 0;              /* next unique ray number */
unsigned long  nrays = 0;               /* number of calls to localhit */

static RREAL  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(), checkhit();
static void  checkset();

#define  RAYHIT         (-1)            /* return value for intercepted ray */


int
rayorigin(r, ro, rt, rw)                /* start new ray from old one */
register RAY  *r, *ro;
int  rt;
double  rw;
{
        double  re;

        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;
                copycolor(r->cext, cextinction);
                copycolor(r->albedo, salbedo);
                r->gecc = seccg;
                r->slights = NULL;
        } else {                                /* spawned ray */
                r->rlvl = ro->rlvl;
                if (rt & RAYREFL) {
                        r->rlvl++;
                        r->rsrc = -1;
                        r->clipset = ro->clipset;
                        r->rmax = 0.0;
                } else {
                        r->rsrc = ro->rsrc;
                        r->clipset = ro->newcset;
                        r->rmax = ro->rmax <= FTINY ? 0.0 : ro->rmax - ro->rot;
                }
                r->revf = ro->revf;
                copycolor(r->cext, ro->cext);
                copycolor(r->albedo, ro->albedo);
                r->gecc = ro->gecc;
                r->slights = ro->slights;
                r->crtype = ro->crtype | (r->rtype = rt);
                VCOPY(r->rorg, ro->rop);
                r->rweight = ro->rweight * rw;
                                                /* estimate absorption */
                re = colval(ro->cext,RED) < colval(ro->cext,GRN) ?
                                colval(ro->cext,RED) : colval(ro->cext,GRN);
                if (colval(ro->cext,BLU) < re) re = colval(ro->cext,BLU);
                if (re > 0.)
                        r->rweight *= exp(-re*ro->rot);
        }
        rayclear(r);
        return(r->rlvl <= maxdepth && r->rweight >= minweight ? 0 : -1);
}


void
rayclear(r)                     /* clear a ray for (re)evaluation */
register RAY  *r;
{
        r->rno = raynum++;
        r->newcset = r->clipset;
        r->hitf = rayhit;
        r->robj = OVOID;
        r->ro = NULL;
        r->rox = NULL;
        r->rt = r->rot = FHUGE;
        r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
        r->uv[0] = r->uv[1] = 0.0;
        setcolor(r->pcol, 1.0, 1.0, 1.0);
        setcolor(r->rcol, 0.0, 0.0, 0.0);
}


void
raytrace(r)                     /* trace a ray and compute its value */
RAY  *r;
{
        if (localhit(r, &thescene))
                raycont(r);             /* hit local surface, evaluate */
        else if (r->ro == &Aftplane) {
                r->ro = NULL;           /* hit aft clipping plane */
                r->rot = FHUGE;
        } else if (sourcehit(r))
                rayshade(r, r->ro->omod);       /* distant source */

        rayparticipate(r);              /* for participating medium */

        if (trace != NULL)
                (*trace)(r);            /* trace execution */
}


void
raycont(r)                      /* check for clipped object and continue */
register RAY  *r;
{
        if ((r->clipset != NULL && inset(r->clipset, r->ro->omod)) ||
                        !rayshade(r, r->ro->omod))
                raytrans(r);
}


void
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;
        }
}


int
rayshade(r, mod)                /* shade ray r with material mod */
register RAY  *r;
int  mod;
{
        int  gotmat;
        register OBJREC  *m;
        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)) &&
                                m->otype != MAT_CLIP &&
                                (ofun[m->otype].flags & (T_M|T_X))) {
                        if (irr_ignore(m->otype)) {
                                raytrans(r);
                                return(1);
                        }
                        if (!islight(m->otype))
                                m = &Lamb;
                }
                                        /* materials call raytexture */
                gotmat = (*ofun[m->otype].funp)(m, r);
        }
        return(gotmat);
}


void
rayparticipate(r)                       /* compute ray medium participation */
register RAY  *r;
{
        COLOR   ce, ca;
        double  re, ge, be;

        if (intens(r->cext) <= 1./FHUGE)
                return;                         /* no medium */
        re = r->rot*colval(r->cext,RED);
        ge = r->rot*colval(r->cext,GRN);
        be = r->rot*colval(r->cext,BLU);
        if (r->crtype & SHADOW) {               /* no scattering for sources */
                re *= 1. - colval(r->albedo,RED);
                ge *= 1. - colval(r->albedo,GRN);
                be *= 1. - colval(r->albedo,BLU);
        }
        setcolor(ce,    re<=0. ? 1. : re>92. ? 0. : exp(-re),
                        ge<=0. ? 1. : ge>92. ? 0. : exp(-ge),
                        be<=0. ? 1. : be>92. ? 0. : exp(-be));
        multcolor(r->rcol, ce);                 /* path absorption */
        if (r->crtype & SHADOW || intens(r->albedo) <= FTINY)
                return;                         /* no scattering */
        setcolor(ca,
                colval(r->albedo,RED)*colval(ambval,RED)*(1.-colval(ce,RED)),
                colval(r->albedo,GRN)*colval(ambval,GRN)*(1.-colval(ce,GRN)),
                colval(r->albedo,BLU)*colval(ambval,BLU)*(1.-colval(ce,BLU)));
        addcolor(r->rcol, ca);                  /* ambient in scattering */
        srcscatter(r);                          /* source in scattering */
}


void
raytexture(r, mod)                      /* get material modifiers */
RAY  *r;
OBJECT  mod;
{
        register OBJREC  *m;
                                        /* 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)) {
                        sprintf(errmsg, "conflicting material \"%s\"",
                                        m->oname);
                        objerror(r->ro, USER, errmsg);
                }
        }
}


int
raymixture(r, fore, back, coef)         /* mix modifiers */
register RAY  *r;
OBJECT  fore, back;
double  coef;
{
        RAY  fr, br;
        int  foremat, backmat;
        register int  i;
                                        /* bound coefficient */
        if (coef > 1.0)
                coef = 1.0;
        else if (coef < 0.0)
                coef = 0.0;
                                        /* compute foreground and background */
        foremat = backmat = 0;
                                        /* foreground */
        fr = *r;
        if (coef > FTINY)
                foremat = rayshade(&fr, fore);
                                        /* background */
        br = *r;
        if (coef < 1.0-FTINY)
                backmat = rayshade(&br, back);
                                        /* check for transparency */
        if (backmat ^ foremat) {
                if (backmat && coef > FTINY)
                        raytrans(&fr);
                else if (foremat && coef < 1.0-FTINY)
                        raytrans(&br);
        }
                                        /* 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);
                                        /* return value tells if material */
        if (!foremat & !backmat)
                return(0);
                                        /* mix returned ray values */
        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(1);
}


double
raydist(r, flags)               /* compute (cumulative) ray distance */
register RAY  *r;
register int  flags;
{
        double  sum = 0.0;

        while (r != NULL && r->crtype&flags) {
                sum += r->rot;
                r = r->parent;
        }
        return(sum);
}


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);
}


void
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 *)malloc(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;
}


void
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];
}


void
rayhit(oset, r)                 /* standard ray hit test */
OBJECT  *oset;
RAY  *r;
{
        OBJREC  *o;
        int     i;

        for (i = oset[0]; i > 0; i--) {
                o = objptr(oset[i]);
                if ((*ofun[o->otype].funp)(o, r))
                        r->robj = oset[i];
        }
}


int
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;
        raymove(curpos, cxset, sflags, r, scene);
        return((r->ro != NULL) & (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 int
checkhit(r, cu, cxs)            /* check for hit in full cube */
register RAY  *r;
CUBE  *cu;
OBJECT  *cxs;
{
        OBJECT  oset[MAXSET+1];

        objset(oset, cu->cutree);
        checkset(oset, cxs);                    /* avoid double-checking */

        (*r->hitf)(oset, r);                    /* test for hit in set */

        if (r->robj == OVOID)
                return(0);                      /* no scores yet */

        return(incube(cu, r->rop));             /* hit OK if in current cube */
}


static void
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:	2.44
Committed:	Wed Dec 31 01:50:02 2003 UTC (21 years, 10 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.43:	+1 -26 lines
Log Message:	Created a source occluder cache to accelerate shadow testing.
#	User	Rev	Content
1	greg	1.1	#ifndef lint
2	greg	2.44	static const char RCSid[] = "$Id: raytrace.c,v 2.43 2003/09/09 03:28:43 greg Exp $";
3	greg	1.1	#endif
4			/*
5			* raytrace.c - routines for tracing and shading rays.
6			*
7	greg	2.34	* External symbols declared in ray.h
8			*/
9
10	greg	2.35	#include "copyright.h"
11	greg	1.1
12			#include "ray.h"
13
14			#include "otypes.h"
15
16	greg	1.15	#include "otspecial.h"
17
18	greg	2.3	#define MAXCSET ((MAXSET+1)2-1) / maximum check set size */
19
20	greg	2.6	unsigned long raynum = 0; /* next unique ray number */
21			unsigned long nrays = 0; /* number of calls to localhit */
22	greg	1.1
23	schorsch	2.40	static RREAL Lambfa[5] = {PI, PI, PI, 0.0, 0.0};
24	greg	1.15	OBJREC Lamb = {
25			OVOID, MAT_PLASTIC, "Lambertian",
26	greg	2.2	{0, 5, NULL, Lambfa}, NULL,
27	greg	1.15	}; /* a Lambertian surface */
28
29	greg	2.17	OBJREC Aftplane; /* aft clipping plane object */
30	greg	2.16
31	greg	2.34	static int raymove(), checkhit();
32			static void checkset();
33	greg	2.5
34	greg	1.1	#define RAYHIT (-1) /* return value for intercepted ray */
35
36
37	greg	2.34	int
38	greg	1.1	rayorigin(r, ro, rt, rw) /* start new ray from old one */
39			register RAY r, ro;
40			int rt;
41			double rw;
42			{
43	gwlarson	2.31	double re;
44
45	greg	1.1	if ((r->parent = ro) == NULL) { /* primary ray */
46			r->rlvl = 0;
47			r->rweight = rw;
48			r->crtype = r->rtype = rt;
49			r->rsrc = -1;
50			r->clipset = NULL;
51	greg	1.21	r->revf = raytrace;
52	greg	2.23	copycolor(r->cext, cextinction);
53	greg	2.26	copycolor(r->albedo, salbedo);
54	greg	2.23	r->gecc = seccg;
55			r->slights = NULL;
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	greg	2.22	r->rmax = 0.0;
63	greg	1.1	} else {
64			r->rsrc = ro->rsrc;
65			r->clipset = ro->newcset;
66	greg	2.22	r->rmax = ro->rmax <= FTINY ? 0.0 : ro->rmax - ro->rot;
67	greg	1.1	}
68	greg	1.21	r->revf = ro->revf;
69	greg	2.23	copycolor(r->cext, ro->cext);
70	greg	2.26	copycolor(r->albedo, ro->albedo);
71	greg	2.23	r->gecc = ro->gecc;
72			r->slights = ro->slights;
73	greg	1.1	r->crtype = ro->crtype \| (r->rtype = rt);
74			VCOPY(r->rorg, ro->rop);
75	gwlarson	2.31	r->rweight = ro->rweight * rw;
76			/* estimate absorption */
77			re = colval(ro->cext,RED) < colval(ro->cext,GRN) ?
78			colval(ro->cext,RED) : colval(ro->cext,GRN);
79			if (colval(ro->cext,BLU) < re) re = colval(ro->cext,BLU);
80			if (re > 0.)
81			r->rweight = exp(-rero->rot);
82	greg	1.1	}
83	greg	1.22	rayclear(r);
84			return(r->rlvl <= maxdepth && r->rweight >= minweight ? 0 : -1);
85			}
86
87
88	greg	2.34	void
89	greg	1.22	rayclear(r) /* clear a ray for (re)evaluation */
90			register RAY *r;
91			{
92	greg	1.20	r->rno = raynum++;
93	greg	1.1	r->newcset = r->clipset;
94	greg	2.36	r->hitf = rayhit;
95	greg	2.28	r->robj = OVOID;
96	greg	2.17	r->ro = NULL;
97	greg	2.34	r->rox = NULL;
98	gregl	2.29	r->rt = r->rot = FHUGE;
99	greg	1.1	r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
100	greg	2.37	r->uv[0] = r->uv[1] = 0.0;
101	greg	1.1	setcolor(r->pcol, 1.0, 1.0, 1.0);
102			setcolor(r->rcol, 0.0, 0.0, 0.0);
103			}
104
105
106	greg	2.34	void
107	greg	1.21	raytrace(r) /* trace a ray and compute its value */
108	greg	1.8	RAY *r;
109	greg	1.1	{
110	greg	1.15	if (localhit(r, &thescene))
111	greg	2.24	raycont(r); /* hit local surface, evaluate */
112	greg	2.16	else if (r->ro == &Aftplane) {
113	greg	2.23	r->ro = NULL; /* hit aft clipping plane */
114	greg	2.16	r->rot = FHUGE;
115			} else if (sourcehit(r))
116	greg	2.24	rayshade(r, r->ro->omod); /* distant source */
117	greg	1.1
118	greg	2.23	rayparticipate(r); /* for participating medium */
119
120	greg	1.1	if (trace != NULL)
121			(trace)(r); / trace execution */
122			}
123
124
125	greg	2.34	void
126	greg	1.8	raycont(r) /* check for clipped object and continue */
127			register RAY *r;
128			{
129	greg	2.7	if ((r->clipset != NULL && inset(r->clipset, r->ro->omod)) \|\|
130	greg	2.24	!rayshade(r, r->ro->omod))
131	greg	1.8	raytrans(r);
132			}
133
134
135	greg	2.34	void
136	greg	1.1	raytrans(r) /* transmit ray as is */
137	greg	1.8	register RAY *r;
138	greg	1.1	{
139			RAY tr;
140
141			if (rayorigin(&tr, r, TRANS, 1.0) == 0) {
142			VCOPY(tr.rdir, r->rdir);
143			rayvalue(&tr);
144			copycolor(r->rcol, tr.rcol);
145	greg	1.10	r->rt = r->rot + tr.rt;
146	greg	1.1	}
147			}
148
149
150	greg	2.34	int
151	greg	1.1	rayshade(r, mod) /* shade ray r with material mod */
152			register RAY *r;
153			int mod;
154			{
155	greg	2.9	int gotmat;
156	greg	1.1	register OBJREC *m;
157	greg	1.19	r->rt = r->rot; /* set effective ray length */
158	greg	2.9	for (gotmat = 0; !gotmat && mod != OVOID; mod = m->omod) {
159	greg	1.1	m = objptr(mod);
160	greg	1.4	/****** unnecessary test since modifier() is always called
161	greg	1.1	if (!ismodifier(m->otype)) {
162			sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
163			error(USER, errmsg);
164			}
165	greg	1.4	******/
166	greg	1.16	/* hack for irradiance calculation */
167	greg	2.38	if (do_irrad && !(r->crtype & ~(PRIMARY\|TRANS)) &&
168	greg	2.43	m->otype != MAT_CLIP &&
169	greg	2.38	(ofun[m->otype].flags & (T_M\|T_X))) {
170	greg	1.16	if (irr_ignore(m->otype)) {
171			raytrans(r);
172	greg	2.15	return(1);
173	greg	1.16	}
174	greg	1.18	if (!islight(m->otype))
175	greg	1.16	m = &Lamb;
176			}
177	greg	2.9	/* materials call raytexture */
178			gotmat = (*ofun[m->otype].funp)(m, r);
179	greg	1.1	}
180	greg	2.9	return(gotmat);
181	greg	2.23	}
182
183
184	greg	2.34	void
185	greg	2.23	rayparticipate(r) /* compute ray medium participation */
186			register RAY *r;
187			{
188			COLOR ce, ca;
189			double re, ge, be;
190
191			if (intens(r->cext) <= 1./FHUGE)
192			return; /* no medium */
193	greg	2.27	re = r->rot*colval(r->cext,RED);
194			ge = r->rot*colval(r->cext,GRN);
195			be = r->rot*colval(r->cext,BLU);
196	greg	2.26	if (r->crtype & SHADOW) { /* no scattering for sources */
197			re *= 1. - colval(r->albedo,RED);
198			ge *= 1. - colval(r->albedo,GRN);
199			be *= 1. - colval(r->albedo,BLU);
200			}
201			setcolor(ce, re<=0. ? 1. : re>92. ? 0. : exp(-re),
202			ge<=0. ? 1. : ge>92. ? 0. : exp(-ge),
203			be<=0. ? 1. : be>92. ? 0. : exp(-be));
204	greg	2.23	multcolor(r->rcol, ce); /* path absorption */
205	greg	2.26	if (r->crtype & SHADOW \|\| intens(r->albedo) <= FTINY)
206	greg	2.23	return; /* no scattering */
207	greg	2.26	setcolor(ca,
208			colval(r->albedo,RED)colval(ambval,RED)(1.-colval(ce,RED)),
209			colval(r->albedo,GRN)colval(ambval,GRN)(1.-colval(ce,GRN)),
210			colval(r->albedo,BLU)colval(ambval,BLU)(1.-colval(ce,BLU)));
211	greg	2.23	addcolor(r->rcol, ca); /* ambient in scattering */
212			srcscatter(r); /* source in scattering */
213	greg	1.1	}
214
215
216	greg	2.39	void
217	greg	1.1	raytexture(r, mod) /* get material modifiers */
218			RAY *r;
219	greg	2.39	OBJECT mod;
220	greg	1.1	{
221	gwlarson	2.33	register OBJREC *m;
222	greg	1.1	/* execute textures and patterns */
223			for ( ; mod != OVOID; mod = m->omod) {
224			m = objptr(mod);
225	greg	2.9	/****** unnecessary test since modifier() is always called
226			if (!ismodifier(m->otype)) {
227	greg	1.1	sprintf(errmsg, "illegal modifier \"%s\"", m->oname);
228			error(USER, errmsg);
229			}
230	greg	2.9	******/
231	greg	2.20	if ((*ofun[m->otype].funp)(m, r)) {
232			sprintf(errmsg, "conflicting material \"%s\"",
233			m->oname);
234			objerror(r->ro, USER, errmsg);
235			}
236	greg	1.1	}
237			}
238
239
240	greg	2.34	int
241	greg	1.1	raymixture(r, fore, back, coef) /* mix modifiers */
242			register RAY *r;
243			OBJECT fore, back;
244			double coef;
245			{
246	greg	2.9	RAY fr, br;
247			int foremat, backmat;
248	greg	1.1	register int i;
249	greg	2.24	/* bound coefficient */
250	greg	1.1	if (coef > 1.0)
251			coef = 1.0;
252			else if (coef < 0.0)
253			coef = 0.0;
254	greg	2.13	/* compute foreground and background */
255	greg	2.24	foremat = backmat = 0;
256	greg	2.9	/* foreground */
257	schorsch	2.41	fr = *r;
258	greg	2.24	if (coef > FTINY)
259	greg	2.9	foremat = rayshade(&fr, fore);
260			/* background */
261	schorsch	2.41	br = *r;
262	greg	2.24	if (coef < 1.0-FTINY)
263	greg	2.9	backmat = rayshade(&br, back);
264	greg	2.24	/* check for transparency */
265	schorsch	2.41	if (backmat ^ foremat) {
266	gwlarson	2.33	if (backmat && coef > FTINY)
267	greg	2.24	raytrans(&fr);
268	gwlarson	2.33	else if (foremat && coef < 1.0-FTINY)
269	greg	2.24	raytrans(&br);
270	schorsch	2.41	}
271	greg	2.12	/* mix perturbations */
272	greg	1.1	for (i = 0; i < 3; i++)
273	greg	2.12	r->pert[i] = coeffr.pert[i] + (1.0-coef)br.pert[i];
274			/* mix pattern colors */
275	greg	2.9	scalecolor(fr.pcol, coef);
276			scalecolor(br.pcol, 1.0-coef);
277	greg	2.12	copycolor(r->pcol, fr.pcol);
278			addcolor(r->pcol, br.pcol);
279	greg	2.24	/* return value tells if material */
280			if (!foremat & !backmat)
281			return(0);
282	greg	2.12	/* mix returned ray values */
283	greg	2.24	scalecolor(fr.rcol, coef);
284			scalecolor(br.rcol, 1.0-coef);
285			copycolor(r->rcol, fr.rcol);
286			addcolor(r->rcol, br.rcol);
287			r->rt = bright(fr.rcol) > bright(br.rcol) ? fr.rt : br.rt;
288			return(1);
289	greg	1.1	}
290
291
292			double
293	greg	2.21	raydist(r, flags) /* compute (cumulative) ray distance */
294			register RAY *r;
295			register int flags;
296			{
297			double sum = 0.0;
298
299			while (r != NULL && r->crtype&flags) {
300			sum += r->rot;
301			r = r->parent;
302			}
303			return(sum);
304			}
305
306
307			double
308	greg	1.1	raynormal(norm, r) /* compute perturbed normal for ray */
309			FVECT norm;
310			register RAY *r;
311			{
312			double newdot;
313			register int i;
314
315			/* The perturbation is added to the surface normal to obtain
316			* the new normal. If the new normal would affect the surface
317			* orientation wrt. the ray, a correction is made. The method is
318			* still fraught with problems since reflected rays and similar
319			* directions calculated from the surface normal may spawn rays behind
320			* the surface. The only solution is to curb textures at high
321	greg	1.9	* incidence (namely, keep DOT(rdir,pert) < Rdot).
322	greg	1.1	*/
323
324			for (i = 0; i < 3; i++)
325			norm[i] = r->ron[i] + r->pert[i];
326
327			if (normalize(norm) == 0.0) {
328			objerror(r->ro, WARNING, "illegal normal perturbation");
329			VCOPY(norm, r->ron);
330			return(r->rod);
331			}
332			newdot = -DOT(norm, r->rdir);
333			if ((newdot > 0.0) != (r->rod > 0.0)) { /* fix orientation */
334			for (i = 0; i < 3; i++)
335			norm[i] += 2.0newdotr->rdir[i];
336			newdot = -newdot;
337			}
338			return(newdot);
339	greg	1.12	}
340
341
342	greg	2.34	void
343	greg	1.12	newrayxf(r) /* get new tranformation matrix for ray */
344			RAY *r;
345			{
346			static struct xfn {
347			struct xfn *next;
348			FULLXF xf;
349			} xfseed = { &xfseed }, *xflast = &xfseed;
350			register struct xfn *xp;
351			register RAY *rp;
352
353			/*
354			* Search for transform in circular list that
355			* has no associated ray in the tree.
356			*/
357			xp = xflast;
358			for (rp = r->parent; rp != NULL; rp = rp->parent)
359			if (rp->rox == &xp->xf) { /* xp in use */
360			xp = xp->next; /* move to next */
361			if (xp == xflast) { /* need new one */
362	greg	2.34	xp = (struct xfn *)malloc(sizeof(struct xfn));
363	greg	1.12	if (xp == NULL)
364			error(SYSTEM,
365			"out of memory in newrayxf");
366			/* insert in list */
367			xp->next = xflast->next;
368			xflast->next = xp;
369			break; /* we're done */
370			}
371			rp = r; /* start check over */
372			}
373			/* got it */
374			r->rox = &xp->xf;
375			xflast = xp;
376	greg	1.1	}
377
378
379	greg	2.34	void
380	greg	1.1	flipsurface(r) /* reverse surface orientation */
381			register RAY *r;
382			{
383			r->rod = -r->rod;
384			r->ron[0] = -r->ron[0];
385			r->ron[1] = -r->ron[1];
386			r->ron[2] = -r->ron[2];
387			r->pert[0] = -r->pert[0];
388			r->pert[1] = -r->pert[1];
389			r->pert[2] = -r->pert[2];
390			}
391
392
393	greg	2.36	void
394			rayhit(oset, r) /* standard ray hit test */
395			OBJECT *oset;
396			RAY *r;
397			{
398			OBJREC *o;
399			int i;
400
401			for (i = oset[0]; i > 0; i--) {
402			o = objptr(oset[i]);
403			if ((*ofun[o->otype].funp)(o, r))
404			r->robj = oset[i];
405			}
406			}
407
408
409	greg	2.34	int
410	greg	1.1	localhit(r, scene) /* check for hit in the octree */
411			register RAY *r;
412			register CUBE *scene;
413			{
414	greg	2.3	OBJECT cxset[MAXCSET+1]; /* set of checked objects */
415	greg	1.1	FVECT curpos; /* current cube position */
416	greg	1.11	int sflags; /* sign flags */
417	greg	1.1	double t, dt;
418			register int i;
419
420	greg	1.21	nrays++; /* increment trace counter */
421	greg	1.11	sflags = 0;
422	greg	1.1	for (i = 0; i < 3; i++) {
423			curpos[i] = r->rorg[i];
424	greg	2.8	if (r->rdir[i] > 1e-7)
425	greg	1.11	sflags \|= 1 << i;
426	greg	2.8	else if (r->rdir[i] < -1e-7)
427	greg	1.11	sflags \|= 0x10 << i;
428	greg	1.1	}
429	greg	1.17	if (sflags == 0)
430			error(CONSISTENCY, "zero ray direction in localhit");
431	greg	2.17	/* start off assuming nothing hit */
432			if (r->rmax > FTINY) { /* except aft plane if one */
433			r->ro = &Aftplane;
434			r->rot = r->rmax;
435			for (i = 0; i < 3; i++)
436			r->rop[i] = r->rorg[i] + r->rot*r->rdir[i];
437			}
438			/* find global cube entrance point */
439	greg	1.1	t = 0.0;
440			if (!incube(scene, curpos)) {
441			/* find distance to entry */
442			for (i = 0; i < 3; i++) {
443			/* plane in our direction */
444	greg	1.11	if (sflags & 1<<i)
445	greg	1.1	dt = scene->cuorg[i];
446	greg	1.11	else if (sflags & 0x10<<i)
447	greg	1.1	dt = scene->cuorg[i] + scene->cusize;
448			else
449			continue;
450			/* distance to the plane */
451			dt = (dt - r->rorg[i])/r->rdir[i];
452			if (dt > t)
453			t = dt; /* farthest face is the one */
454			}
455			t += FTINY; /* fudge to get inside cube */
456	greg	2.17	if (t >= r->rot) /* clipped already */
457			return(0);
458	greg	1.1	/* advance position */
459			for (i = 0; i < 3; i++)
460			curpos[i] += r->rdir[i]*t;
461
462			if (!incube(scene, curpos)) /* non-intersecting ray */
463			return(0);
464			}
465	greg	2.3	cxset[0] = 0;
466	greg	2.19	raymove(curpos, cxset, sflags, r, scene);
467	schorsch	2.42	return((r->ro != NULL) & (r->ro != &Aftplane));
468	greg	1.1	}
469
470
471			static int
472	greg	2.3	raymove(pos, cxs, dirf, r, cu) /* check for hit as we move */
473			FVECT pos; /* current position, modified herein */
474			OBJECT cxs; / checked objects, modified by checkhit */
475	greg	1.11	int dirf; /* direction indicators to speed tests */
476	greg	1.1	register RAY *r;
477			register CUBE *cu;
478			{
479			int ax;
480			double dt, t;
481
482			if (istree(cu->cutree)) { /* recurse on subcubes */
483			CUBE cukid;
484	greg	1.11	register int br, sgn;
485	greg	1.1
486			cukid.cusize = cu->cusize * 0.5; /* find subcube */
487			VCOPY(cukid.cuorg, cu->cuorg);
488			br = 0;
489			if (pos[0] >= cukid.cuorg[0]+cukid.cusize) {
490			cukid.cuorg[0] += cukid.cusize;
491			br \|= 1;
492			}
493			if (pos[1] >= cukid.cuorg[1]+cukid.cusize) {
494			cukid.cuorg[1] += cukid.cusize;
495			br \|= 2;
496			}
497			if (pos[2] >= cukid.cuorg[2]+cukid.cusize) {
498			cukid.cuorg[2] += cukid.cusize;
499			br \|= 4;
500			}
501			for ( ; ; ) {
502			cukid.cutree = octkid(cu->cutree, br);
503	greg	2.3	if ((ax = raymove(pos,cxs,dirf,r,&cukid)) == RAYHIT)
504	greg	1.1	return(RAYHIT);
505			sgn = 1 << ax;
506	greg	1.11	if (sgn & dirf) /* positive axis? */
507	greg	1.1	if (sgn & br)
508			return(ax); /* overflow */
509			else {
510			cukid.cuorg[ax] += cukid.cusize;
511			br \|= sgn;
512			}
513	greg	1.11	else
514			if (sgn & br) {
515			cukid.cuorg[ax] -= cukid.cusize;
516			br &= ~sgn;
517			} else
518			return(ax); /* underflow */
519	greg	1.1	}
520			/NOTREACHED/
521			}
522	greg	2.18	if (isfull(cu->cutree)) {
523			if (checkhit(r, cu, cxs))
524			return(RAYHIT);
525			} else if (r->ro == &Aftplane && incube(cu, r->rop))
526	greg	1.1	return(RAYHIT);
527			/* advance to next cube */
528	greg	1.11	if (dirf&0x11) {
529			dt = dirf&1 ? cu->cuorg[0] + cu->cusize : cu->cuorg[0];
530	greg	1.1	t = (dt - pos[0])/r->rdir[0];
531			ax = 0;
532			} else
533			t = FHUGE;
534	greg	1.11	if (dirf&0x22) {
535			dt = dirf&2 ? cu->cuorg[1] + cu->cusize : cu->cuorg[1];
536	greg	1.1	dt = (dt - pos[1])/r->rdir[1];
537			if (dt < t) {
538			t = dt;
539			ax = 1;
540			}
541			}
542	greg	1.11	if (dirf&0x44) {
543			dt = dirf&4 ? cu->cuorg[2] + cu->cusize : cu->cuorg[2];
544	greg	1.1	dt = (dt - pos[2])/r->rdir[2];
545			if (dt < t) {
546			t = dt;
547			ax = 2;
548			}
549			}
550			pos[0] += r->rdir[0]*t;
551			pos[1] += r->rdir[1]*t;
552			pos[2] += r->rdir[2]*t;
553			return(ax);
554			}
555
556
557	greg	2.34	static int
558	greg	2.3	checkhit(r, cu, cxs) /* check for hit in full cube */
559	greg	1.1	register RAY *r;
560			CUBE *cu;
561	greg	2.3	OBJECT *cxs;
562	greg	1.1	{
563			OBJECT oset[MAXSET+1];
564
565			objset(oset, cu->cutree);
566	greg	2.36	checkset(oset, cxs); /* avoid double-checking */
567
568			(r->hitf)(oset, r); / test for hit in set */
569
570			if (r->robj == OVOID)
571	greg	1.1	return(0); /* no scores yet */
572
573			return(incube(cu, r->rop)); /* hit OK if in current cube */
574	greg	2.2	}
575
576
577	greg	2.34	static void
578	greg	2.2	checkset(os, cs) /* modify checked set and set to check */
579	greg	2.3	register OBJECT os; / os' = os - cs */
580			register OBJECT cs; / cs' = cs + os */
581	greg	2.2	{
582			OBJECT cset[MAXCSET+MAXSET+1];
583	greg	2.3	register int i, j;
584			int k;
585	greg	2.2	/* copy os in place, cset <- cs */
586			cset[0] = 0;
587			k = 0;
588			for (i = j = 1; i <= os[0]; i++) {
589			while (j <= cs[0] && cs[j] < os[i])
590			cset[++cset[0]] = cs[j++];
591			if (j > cs[0] \|\| os[i] != cs[j]) { /* object to check */
592			os[++k] = os[i];
593			cset[++cset[0]] = os[i];
594			}
595			}
596	greg	2.3	if (!(os[0] = k)) /* new "to check" set size */
597			return; /* special case */
598	greg	2.2	while (j <= cs[0]) /* get the rest of cs */
599			cset[++cset[0]] = cs[j++];
600	greg	2.3	if (cset[0] > MAXCSET) /* truncate "checked" set if nec. */
601	greg	2.2	cset[0] = MAXCSET;
602	greg	2.3	/* setcopy(cs, cset); / / copy cset back to cs */
603			os = cset;
604			for (i = os[0]; i-- >= 0; )
605			cs++ = os++;
606	greg	1.1	}