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raytrace.c
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#ifndef lint
static const char RCSid[] = "$Id: raytrace.c,v 2.85 2021/06/09 18:21:10 greg Exp $";
#endif
/*
* raytrace.c - routines for tracing and shading rays.
*
* External symbols declared in ray.h
*/
#include "copyright.h"
#include "ray.h"
#include "source.h"
#include "otypes.h"
#include "otspecial.h"
#include "random.h"
#include "pmap.h"
#define MAXCSET ((MAXSET+1)*2-1) /* maximum check set size */
RNUMBER raynum = 0; /* next unique ray number */
RNUMBER nrays = 0; /* number of calls to localhit */
static RREAL Lambfa[5] = {PI, PI, PI, 0.0, 0.0};
OBJREC Lamb = {
OVOID, MAT_PLASTIC, "Lambertian",
{NULL, Lambfa, 0, 5}, NULL
}; /* a Lambertian surface */
OBJREC Aftplane; /* aft clipping plane object */
#define RAYHIT (-1) /* return value for intercepted ray */
static int raymove(FVECT pos, OBJECT *cxs, int dirf, RAY *r, CUBE *cu);
static int checkhit(RAY *r, CUBE *cu, OBJECT *cxs);
static void checkset(OBJECT *os, OBJECT *cs);
int
rayorigin( /* start new ray from old one */
RAY *r,
int rt,
const RAY *ro,
const COLOR rc
)
{
double rw, re;
/* assign coefficient/weight */
if (rc == NULL) {
rw = 1.0;
setcolor(r->rcoef, 1., 1., 1.);
} else {
rw = intens(rc);
if (rw > 1.0)
rw = 1.0; /* avoid calculation growth */
if (rc != r->rcoef)
copycolor(r->rcoef, rc);
}
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 */
if (ro->rot >= FHUGE*.99) {
memset(r, 0, sizeof(RAY));
return(-1); /* illegal continuation */
}
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 extinction */
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);
re *= ro->rot;
if (re > 0.1) {
if (re > 92.) {
r->rweight = 0.0;
} else {
r->rweight *= exp(-re);
}
}
}
rayclear(r);
if (r->rweight <= 0.0) /* check for expiration */
return(-1);
if (r->crtype & SHADOW) /* shadow commitment */
return(0);
/* ambient in photon map? */
if (ro != NULL && ro->crtype & AMBIENT) {
if (causticPhotonMapping)
return(-1);
if (photonMapping && rt != TRANS)
return(-1);
}
if ((maxdepth <= 0) & (rc != NULL)) { /* Russian roulette */
if (minweight <= 0.0)
error(USER, "zero ray weight in Russian roulette");
if ((maxdepth < 0) & (r->rlvl > -maxdepth))
return(-1); /* upper reflection limit */
if (r->rweight >= minweight)
return(0);
if (frandom() > r->rweight/minweight)
return(-1);
rw = minweight/r->rweight; /* promote survivor */
scalecolor(r->rcoef, rw);
r->rweight = minweight;
return(0);
}
return((r->rweight >= minweight) & (r->rlvl <= abs(maxdepth)) ? 0 : -1);
}
void
rayclear( /* clear a ray for (re)evaluation */
RAY *r
)
{
r->rno = raynum++;
r->newcset = r->clipset;
r->hitf = rayhit;
r->robj = OVOID;
r->ro = NULL;
r->rox = NULL;
r->rxt = r->rmt = r->rot = FHUGE;
VCOPY(r->rop, r->rorg);
r->ron[0] = -r->rdir[0]; r->ron[1] = -r->rdir[1]; r->ron[2] = -r->rdir[2];
r->rod = 1.0;
r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
r->rflips = 0;
r->uv[0] = r->uv[1] = 0.0;
setcolor(r->pcol, 1.0, 1.0, 1.0);
setcolor(r->mcol, 0.0, 0.0, 0.0);
setcolor(r->rcol, 0.0, 0.0, 0.0);
}
void
raytrace( /* 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 */
if (trace != NULL)
(*trace)(r); /* trace execution */
rayparticipate(r); /* for participating medium */
}
void
raycont( /* check for clipped object and continue */
RAY *r
)
{
if ((r->clipset != NULL && inset(r->clipset, r->ro->omod)) ||
!rayshade(r, r->ro->omod))
raytrans(r);
}
void
raytrans( /* transmit ray as is */
RAY *r
)
{
RAY tr;
rayorigin(&tr, TRANS, r, NULL); /* always continue */
VCOPY(tr.rdir, r->rdir);
rayvalue(&tr);
copycolor(r->mcol, tr.mcol);
copycolor(r->rcol, tr.rcol);
r->rmt = r->rot + tr.rmt;
r->rxt = r->rot + tr.rxt;
}
int
raytirrad( /* irradiance hack */
OBJREC *m,
RAY *r
)
{
if (ofun[m->otype].flags & (T_M|T_X) && m->otype != MAT_CLIP) {
if (istransp(m->otype) || isBSDFproxy(m)) {
raytrans(r);
return(1);
}
if (!islight(m->otype))
return((*ofun[Lamb.otype].funp)(&Lamb, r));
}
return(0); /* not a qualifying surface */
}
int
rayshade( /* shade ray r with material mod */
RAY *r,
int mod
)
{
int tst_irrad = do_irrad && !(r->crtype & ~(PRIMARY|TRANS));
OBJREC *m;
r->rxt = r->rot; /* preset 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 (tst_irrad && raytirrad(m, r))
return(1);
if ((*ofun[m->otype].funp)(m, r))
return(1); /* materials call raytexture() */
}
return(0); /* no material! */
}
void
rayparticipate( /* compute ray medium participation */
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<=FTINY ? 1. : re>92. ? 0. : exp(-re),
ge<=FTINY ? 1. : ge>92. ? 0. : exp(-ge),
be<=FTINY ? 1. : be>92. ? 0. : exp(-be));
multcolor(r->rcol, ce); /* path extinction */
if (r->crtype & SHADOW || intens(r->albedo) <= FTINY)
return; /* no scattering */
/* PMAP: indirect inscattering accounted for by volume photons? */
if (!volumePhotonMapping) {
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( /* get material modifiers */
RAY *r,
OBJECT mod
)
{
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( /* mix modifiers */
RAY *r,
OBJECT fore,
OBJECT back,
double coef
)
{
RAY fr, br;
double mfore, mback;
int foremat, backmat;
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) {
fr.rweight *= coef;
scalecolor(fr.rcoef, coef);
foremat = rayshade(&fr, fore);
}
/* background */
br = *r;
if (coef < 1.0-FTINY) {
br.rweight *= 1.0-coef;
scalecolor(br.rcoef, 1.0-coef);
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);
scalecolor(fr.mcol, coef);
scalecolor(br.mcol, 1.0-coef);
copycolor(r->mcol, fr.mcol);
addcolor(r->mcol, br.mcol);
mfore = bright(fr.mcol); mback = bright(br.mcol);
r->rmt = mfore > mback ? fr.rmt : br.rmt;
r->rxt = bright(fr.rcol)-mfore > bright(br.rcol)-mback ?
fr.rxt : br.rxt;
return(1);
}
double
raydist( /* compute (cumulative) ray distance */
const RAY *r,
int flags
)
{
double sum = 0.0;
while (r != NULL && r->crtype&flags) {
sum += r->rot;
r = r->parent;
}
return(sum);
}
void
raycontrib( /* compute (cumulative) ray contribution */
RREAL rc[3],
const RAY *r,
int flags
)
{
static int warnedPM = 0;
rc[0] = rc[1] = rc[2] = 1.;
while (r != NULL && r->crtype&flags) {
int i = 3;
while (i--)
rc[i] *= colval(r->rcoef,i);
/* check for participating medium */
if (!warnedPM && (bright(r->cext) > FTINY) |
(bright(r->albedo) > FTINY)) {
error(WARNING,
"ray contribution calculation does not support participating media");
warnedPM++;
}
r = r->parent;
}
}
double
raynormal( /* compute perturbed normal for ray */
FVECT norm,
RAY *r
)
{
double newdot;
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( /* get new tranformation matrix for ray */
RAY *r
)
{
static struct xfn {
struct xfn *next;
FULLXF xf;
} xfseed = { &xfseed }, *xflast = &xfseed;
struct xfn *xp;
const 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;
}
void
flipsurface( /* reverse surface orientation */
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];
r->rflips++;
}
int
rayreject( /* check if candidate hit is worse than current */
OBJREC *o,
RAY *r,
double t
)
{
OBJREC *mnew, *mray;
if ((t <= FTINY) | (t > r->rot + FTINY))
return(1);
if (t < r->rot - FTINY) /* is new hit significantly closer? */
return(0);
/* coincident point, so decide... */
if (o == r->ro)
return(1); /* shouldn't happen */
if (r->ro == NULL)
return(0); /* ditto */
mnew = findmaterial(o);
mray = findmaterial(r->ro); /* check material transparencies */
if (mnew == NULL) {
if (mray != NULL)
return(1); /* new has no material */
} else if (mray == NULL) {
return(0); /* old has no material(!) */
} else if (istransp(mnew->otype)) {
if (!istransp(mray->otype))
return(1); /* new is transparent */
} else if (istransp(mray->otype)) {
return(0); /* old is transparent */
}
/* weakest priority to later modifier definition */
return (r->ro->omod >= o->omod);
}
void
rayhit( /* 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( /* check for hit in the octree */
RAY *r,
CUBE *scene
)
{
OBJECT cxset[MAXCSET+1]; /* set of checked objects */
FVECT curpos; /* current cube position */
int sflags; /* sign flags */
double t, dt;
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) {
error(WARNING, "zero ray direction in localhit");
return(0);
}
/* start off assuming nothing hit */
if (r->rmax > FTINY) { /* except aft plane if one */
r->ro = &Aftplane;
r->rot = r->rmax;
VSUM(r->rop, r->rorg, r->rdir, r->rot);
}
/* 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 */
VSUM(curpos, curpos, r->rdir, 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( /* 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 */
RAY *r,
CUBE *cu
)
{
int ax;
double dt, t;
if (istree(cu->cutree)) { /* recurse on subcubes */
CUBE cukid;
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;
}
}
VSUM(pos, pos, r->rdir, t);
return(ax);
}
static int
checkhit( /* check for hit in full cube */
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( /* modify checked set and set to check */
OBJECT *os, /* os' = os - cs */
OBJECT *cs /* cs' = cs + os */
)
{
OBJECT cset[MAXCSET+MAXSET+1];
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++;
}

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