Logo Search packages:      
Sourcecode: radiance version File versions  Download package

raytrace.c

#ifndef lint
static const char RCSid[] = "$Id: raytrace.c,v 2.59 2007/07/02 20:16:00 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"

#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",
      {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);


extern 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 (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) {
                  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);
      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->rlvl <= abs(maxdepth) && r->rweight >= minweight ? 0 : -1);
}


extern void
rayclear(               /* 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);
}


extern 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 */
}


extern void
raycont(                /* 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);
}


extern void
raytrans(               /* transmit ray as is */
      register RAY  *r
)
{
      RAY  tr;

      if (rayorigin(&tr, TRANS, r, NULL) == 0) {
            VCOPY(tr.rdir, r->rdir);
            rayvalue(&tr);
            copycolor(r->rcol, tr.rcol);
            r->rt = r->rot + tr.rt;
      }
}


extern int
rayshade(         /* shade ray r with material mod */
      register RAY  *r,
      int  mod
)
{
      register OBJREC  *m;

      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)) &&
                        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;
            }
            if ((*ofun[m->otype].funp)(m, r))
                  return(1);  /* materials call raytexture() */
      }
      return(0);              /* no material! */
}


extern void
rayparticipate(               /* 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<=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 */
      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 */
}


extern void
raytexture(             /* 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);
            }
      }
}


extern int
raymixture(       /* mix modifiers */
      register RAY  *r,
      OBJECT  fore,
      OBJECT  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) {
            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);
      r->rt = bright(fr.rcol) > bright(br.rcol) ? fr.rt : br.rt;
      return(1);
}


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

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


extern void
raycontrib(       /* compute (cumulative) ray contribution */
      double  rc[3],
      const RAY  *r,
      int  flags
)
{
      double      eext[3];
      int   i;

      eext[0] = eext[1] = eext[2] = 0.;
      rc[0] = rc[1] = rc[2] = 1.;

      while (r != NULL && r->crtype&flags) {
            for (i = 3; i--; ) {
                  rc[i] *= colval(r->rcoef,i);
                  eext[i] += r->rot * colval(r->cext,i);
            }
            r = r->parent;
      }
      for (i = 3; i--; )
            rc[i] *= (eext[i] <= FTINY) ? 1. :
                        (eext[i] > 92.) ? 0. : exp(-eext[i]);
}


extern double
raynormal(        /* 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);
}


extern void
newrayxf(               /* 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 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 *)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;
}


extern void
flipsurface(                  /* 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];
}


extern 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];
      }
}


extern int
localhit(         /* 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(          /* 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(         /* 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(         /* 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++;
}

Generated by  Doxygen 1.6.0   Back to index