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srcdraw.c

#ifndef lint
static const char RCSid[] = "$Id: srcdraw.c,v 2.16 2005/04/19 01:15:07 greg Exp $";
#endif
/*
 * Draw small sources into image in case we missed them.
 *
 *  External symbols declared in ray.h
 */

#include "copyright.h"

#include  "ray.h"
#include  "view.h"
#include  "otypes.h"
#include  "source.h"


#define     CLIP_ABOVE  1
#define CLIP_BELOW      2
#define CLIP_RIGHT      3
#define CLIP_LEFT 4

#define MAXVERT         10

typedef struct splist {
      struct splist     *next;                  /* next source in list */
      int   sn;                     /* source number */
      short nv;                     /* number of vertices */
      RREAL vl[3][2];               /* vertex array (last) */
} SPLIST;                     /* source polygon list */

extern VIEW ourview;          /* our view parameters */
extern int  hres, vres;       /* our image resolution */
static SPLIST     *sphead = NULL;         /* our list of source polys */

static int inregion(RREAL p[2], double cv, int crit);
static void clipregion(RREAL a[2], RREAL b[2], double cv, int crit, RREAL r[2]);
static int hp_clip_poly(RREAL vl[][2], int nv, double cv, int crit,
            RREAL vlo[][2]);
static int box_clip_poly(RREAL vl[MAXVERT][2], int nv,
            double xl, double xr, double yb, double ya, RREAL vlo[MAXVERT][2]);
static double minw2(RREAL vl[][2], int nv, double ar2);
static void convex_center(RREAL vl[][2], int nv, RREAL cv[2]);
static double poly_area(RREAL vl[][2], int nv);
static int convex_hull(RREAL vl[][2], int nv, RREAL vlo[][2]);
static void spinsert(int sn, RREAL vl[][2], int nv);
static int sourcepoly(int sn, RREAL sp[MAXVERT][2]);


static int
inregion(               /* check if vertex is in region */
      RREAL p[2],
      double      cv,
      int   crit
)
{
      switch (crit) {
      case CLIP_ABOVE:
            return(p[1] < cv);
      case CLIP_BELOW:
            return(p[1] >= cv);
      case CLIP_RIGHT:
            return(p[0] < cv);
      case CLIP_LEFT:
            return(p[0] >= cv);
      }
      return(-1);
}


static void
clipregion(       /* find intersection with boundary */
      register RREAL    a[2],
      register RREAL    b[2],
      double      cv,
      int   crit,
      RREAL r[2]  /* return value */
)
{
      switch (crit) {
      case CLIP_ABOVE:
      case CLIP_BELOW:
            r[1] = cv;
            r[0] = a[0] + (cv-a[1])/(b[1]-a[1])*(b[0]-a[0]);
            return;
      case CLIP_RIGHT:
      case CLIP_LEFT:
            r[0] = cv;
            r[1] = a[1] + (cv-a[0])/(b[0]-a[0])*(b[1]-a[1]);
            return;
      }
}


static int
hp_clip_poly(     /* clip polygon to half-plane */
      RREAL vl[][2],
      int   nv,
      double      cv,
      int   crit,
      RREAL vlo[][2]    /* return value */
)
{
      RREAL *s, *p;
      register int      j, nvo;

      s = vl[nv-1];
      nvo = 0;
      for (j = 0; j < nv; j++) {
            p = vl[j];
            if (inregion(p, cv, crit)) {
                  if (!inregion(s, cv, crit))
                        clipregion(s, p, cv, crit, vlo[nvo++]);
                  vlo[nvo][0] = p[0]; vlo[nvo++][1] = p[1];
            } else if (inregion(s, cv, crit))
                  clipregion(s, p, cv, crit, vlo[nvo++]);
            s = p;
      }
      return(nvo);
}


static int
box_clip_poly(    /* clip polygon to box */
      RREAL vl[MAXVERT][2],
      int   nv,
      double      xl,
      double      xr,
      double      yb,
      double      ya,
      RREAL vlo[MAXVERT][2]   /* return value */
)
{
      RREAL vlt[MAXVERT][2];
      int   nvt, nvo;

      nvt = hp_clip_poly(vl, nv, yb, CLIP_BELOW, vlt);
      nvo = hp_clip_poly(vlt, nvt, ya, CLIP_ABOVE, vlo);
      nvt = hp_clip_poly(vlo, nvo, xl, CLIP_LEFT, vlt);
      nvo = hp_clip_poly(vlt, nvt, xr, CLIP_RIGHT, vlo);

      return(nvo);
}


static double
minw2(                  /* compute square of minimum width */
      RREAL vl[][2],
      int   nv,
      double      ar2
)
{
      double      d2, w2, w2min, w2max;
      register RREAL    *p0, *p1, *p2;
      int   i, j;
                        /* find minimum for all widths */
      w2min = FHUGE;
      p0 = vl[nv-1];
      for (i = 0; i < nv; i++) {    /* for each edge */
            p1 = vl[i];
            d2 = (p1[0]-p0[0])*(p1[0]-p0[0]) +
                        (p1[1]-p0[1])*(p1[1]-p0[1])*ar2;
            w2max = 0.;       /* find maximum for this side */
            for (j = 1; j < nv-1; j++) {
                  p2 = vl[(i+j)%nv];
                  w2 = (p1[0]-p0[0])*(p2[1]-p0[1]) -
                              (p1[1]-p0[1])*(p2[0]-p0[0]);
                  w2 = w2*w2*ar2/d2;      /* triangle height squared */
                  if (w2 > w2max)
                        w2max = w2;
            }
            if (w2max < w2min)      /* global min. based on local max.'s */
                  w2min = w2max;
            p0 = p1;
      }
      return(w2min);
}


static void
convex_center(          /* compute center of convex polygon */
      register RREAL    vl[][2],
      int   nv,
      RREAL cv[2]       /* return value */
)
{
      register int      i;
                              /* simple average (suboptimal) */
      cv[0] = cv[1] = 0.;
      for (i = 0; i < nv; i++) {
            cv[0] += vl[i][0];
            cv[1] += vl[i][1];
      }
      cv[0] /= (double)nv;
      cv[1] /= (double)nv;
}


static double
poly_area(              /* compute area of polygon */
      register RREAL    vl[][2],
      int   nv
)
{
      double      a;
      RREAL v0[2], v1[2];
      register int      i;

      a = 0.;
      v0[0] = vl[1][0] - vl[0][0];
      v0[1] = vl[1][1] - vl[0][1];
      for (i = 2; i < nv; i++) {
            v1[0] = vl[i][0] - vl[0][0];
            v1[1] = vl[i][1] - vl[0][1];
            a += v0[0]*v1[1] - v0[1]*v1[0];
            v0[0] = v1[0]; v0[1] = v1[1];
      }
      return(a * (a >= 0. ? .5 : -.5));
}


static int
convex_hull(            /* compute polygon's convex hull */
      RREAL vl[][2],
      int   nv,
      RREAL vlo[][2]    /* return value */
)
{
      int   nvo, nvt;
      RREAL vlt[MAXVERT][2];
      double      voa, vta;
      register int      i, j;
                              /* start with original polygon */
      for (i = nvo = nv; i--; ) {
            vlo[i][0] = vl[i][0]; vlo[i][1] = vl[i][1];
      }
      voa = poly_area(vlo, nvo);    /* compute its area */
      for (i = 0; i < nvo; i++) {         /* for each output vertex */
            for (j = 0; j < i; j++) {
                  vlt[j][0] = vlo[j][0]; vlt[j][1] = vlo[j][1];
            }
            nvt = nvo - 1;                /* make poly w/o vertex */
            for (j = i; j < nvt; j++) {
                  vlt[j][0] = vlo[j+1][0]; vlt[j][1] = vlo[j+1][1];
            }
            vta = poly_area(vlt, nvt);
            if (vta >= voa) {       /* is simpler poly bigger? */
                  voa = vta;              /* then use it */
                  for (j = nvo = nvt; j--; ) {
                        vlo[j][0] = vlt[j][0]; vlo[j][1] = vlt[j][1];
                  }
                  i--;                    /* next adjust */
            }
      }
      return(nvo);
}


static void
spinsert(               /* insert new source polygon */
      int   sn,
      RREAL vl[][2],
      int   nv
)
{
      register SPLIST   *spn;
      register int      i;

      if (nv < 3)
            return;
      if (nv > 3)
            spn = (SPLIST *)malloc(sizeof(SPLIST)+sizeof(RREAL)*2*(nv-3));
      else
            spn = (SPLIST *)malloc(sizeof(SPLIST));
      if (spn == NULL)
            error(SYSTEM, "out of memory in spinsert");
      spn->sn = sn;
      for (i = spn->nv = nv; i--; ) {
            spn->vl[i][0] = vl[i][0]; spn->vl[i][1] = vl[i][1];
      }
      spn->next = sphead;           /* push onto global list */
      sphead = spn;
}


static int
sourcepoly(             /* compute image polygon for source */
      int   sn,
      RREAL sp[MAXVERT][2]
)
{
      static short      cubeord[8][6] = {{1,3,2,6,4,5},{0,4,5,7,3,2},
                               {0,1,3,7,6,4},{0,1,5,7,6,2},
                               {0,2,6,7,5,1},{0,4,6,7,3,1},
                               {0,2,3,7,5,4},{1,5,4,6,2,3}};
      register SRCREC   *s = source + sn;
      FVECT ap, ip;
      RREAL pt[6][2];
      int   dir;
      register int      i, j;

      if (s->sflags & (SDISTANT|SFLAT)) {
            if (s->sflags & SDISTANT) {
                  if (ourview.type == VT_PAR)
                        return(0);  /* all or nothing case */
                  if (s->srad >= 0.05)
                        return(0);  /* should never be a problem */
            }
            if (s->sflags & SFLAT) {
                  for (i = 0; i < 3; i++)
                        ap[i] = s->sloc[i] - ourview.vp[i];
                  if (DOT(ap, s->snorm) >= 0.)
                        return(0);  /* source faces away */
            }
            for (j = 0; j < 4; j++) {     /* four corners */
                  for (i = 0; i < 3; i++) {
                        ap[i] = s->sloc[i];
                        if ((j==1)|(j==2)) ap[i] += s->ss[SU][i];
                        else ap[i] -= s->ss[SU][i];
                        if ((j==2)|(j==3)) ap[i] += s->ss[SV][i];
                        else ap[i] -= s->ss[SV][i];
                        if (s->sflags & SDISTANT) {
                              ap[i] *= 1. + ourview.vfore;
                              ap[i] += ourview.vp[i];
                        }
                  }
                  viewloc(ip, &ourview, ap);    /* find image point */
                  if (ip[2] <= 0.)
                        return(0);        /* in front of view */
                  sp[j][0] = ip[0]; sp[j][1] = ip[1];
            }
            return(4);
      }
                              /* identify furthest corner */
      for (i = 0; i < 3; i++)
            ap[i] = s->sloc[i] - ourview.vp[i];
      dir = (DOT(ap,s->ss[SU])>0.) |
            (DOT(ap,s->ss[SV])>0.)<<1 |
            (DOT(ap,s->ss[SW])>0.)<<2 ;
                              /* order vertices based on this */
      for (j = 0; j < 6; j++) {
            for (i = 0; i < 3; i++) {
                  ap[i] = s->sloc[i];
                  if (cubeord[dir][j] & 1) ap[i] += s->ss[SU][i];
                  else ap[i] -= s->ss[SU][i];
                  if (cubeord[dir][j] & 2) ap[i] += s->ss[SV][i];
                  else ap[i] -= s->ss[SV][i];
                  if (cubeord[dir][j] & 4) ap[i] += s->ss[SW][i];
                  else ap[i] -= s->ss[SW][i];
            }
            viewloc(ip, &ourview, ap);    /* find image point */
            if (ip[2] <= 0.)
                  return(0);        /* in front of view */
            pt[j][0] = ip[0]; pt[j][1] = ip[1];
      }
      return(convex_hull(pt, 6, sp));           /* make sure it's convex */
}


                  /* initialize by finding sources smaller than rad */
extern void
init_drawsources(
      int   rad                     /* source sample size */
)
{
      RREAL spoly[MAXVERT][2];
      int   nsv;
      register SPLIST   *sp;
      register int      i;
                              /* free old source list if one */
      for (sp = sphead; sp != NULL; sp = sphead) {
            sphead = sp->next;
            free((void *)sp);
      }
                              /* loop through all sources */
      for (i = nsources; i--; ) {
                              /* skip illum's */
            if (findmaterial(source[i].so)->otype == MAT_ILLUM)
                  continue;
                              /* compute image polygon for source */
            if (!(nsv = sourcepoly(i, spoly)))
                  continue;
                              /* clip to image boundaries */
            if (!(nsv = box_clip_poly(spoly, nsv, 0., 1., 0., 1., spoly)))
                  continue;
                              /* big enough for standard sampling? */
            if (minw2(spoly, nsv, ourview.vn2/ourview.hn2) >
                        (double)rad*rad/hres/hres)
                  continue;
                              /* OK, add to our list */
            spinsert(i, spoly, nsv);
      }
}

extern void             /* add sources smaller than rad to computed subimage */
drawsources(
      COLOR *pic[],                       /* subimage pixel value array */
      float *zbf[],                       /* subimage distance array (opt.) */
      int   x0,                     /* origin and size of subimage */
      int   xsiz,
      int   y0,
      int   ysiz
)
{
      RREAL spoly[MAXVERT][2], ppoly[MAXVERT][2];
      int   nsv, npv;
      int   xmin, xmax, ymin, ymax, x, y;
      RREAL cxy[2];
      double      w;
      RAY   sr;
      register SPLIST   *sp;
      register int      i;
                              /* check each source in our list */
      for (sp = sphead; sp != NULL; sp = sp->next) {
                              /* clip source poly to subimage */
            nsv = box_clip_poly(sp->vl, sp->nv,
                        (double)x0/hres, (double)(x0+xsiz)/hres,
                        (double)y0/vres, (double)(y0+ysiz)/vres, spoly);
            if (!nsv)
                  continue;
                              /* find common subimage (BBox) */
            xmin = x0 + xsiz; xmax = x0;
            ymin = y0 + ysiz; ymax = y0;
            for (i = 0; i < nsv; i++) {
                  if ((double)xmin/hres > spoly[i][0])
                        xmin = spoly[i][0]*hres + FTINY;
                  if ((double)xmax/hres < spoly[i][0])
                        xmax = spoly[i][0]*hres - FTINY;
                  if ((double)ymin/vres > spoly[i][1])
                        ymin = spoly[i][1]*vres + FTINY;
                  if ((double)ymax/vres < spoly[i][1])
                        ymax = spoly[i][1]*vres - FTINY;
            }
                              /* evaluate each pixel in BBox */
            for (y = ymin; y <= ymax; y++)
                  for (x = xmin; x <= xmax; x++) {
                                          /* subarea for pixel */
                        npv = box_clip_poly(spoly, nsv,
                                    (double)x/hres, (x+1.)/hres,
                                    (double)y/vres, (y+1.)/vres,
                                    ppoly);
                        if (!npv)
                              continue;   /* no overlap */
                        convex_center(ppoly, npv, cxy);
                        if ((sr.rmax = viewray(sr.rorg,sr.rdir,&ourview,
                                    cxy[0],cxy[1])) < -FTINY)
                              continue;   /* not in view */
                        if (source[sp->sn].sflags & SSPOT &&
                                    spotout(&sr, source[sp->sn].sl.s))
                              continue;   /* outside spot */
                        rayorigin(&sr, SHADOW, NULL, NULL);
                        sr.rsrc = sp->sn;
                        rayvalue(&sr);          /* compute value */
                        if (bright(sr.rcol) <= FTINY)
                              continue;   /* missed/blocked */
                                          /* modify pixel */
                        w = poly_area(ppoly, npv) * hres * vres;
                        if (zbf[y-y0] != NULL &&
                                    sr.rt < 0.99*zbf[y-y0][x-x0]) {
                              zbf[y-y0][x-x0] = sr.rt;
                        } else if (!bigdiff(sr.rcol, pic[y-y0][x-x0],
                                    0.01)) { /* source sample */
                              scalecolor(pic[y-y0][x-x0], w);
                              continue;
                        }
                        scalecolor(sr.rcol, w);
                        scalecolor(pic[y-y0][x-x0], 1.-w);
                        addcolor(pic[y-y0][x-x0], sr.rcol);
                  }
      }
}

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