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srcdraw.c
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Mon, Jun 10, 05:07

srcdraw.c
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#ifndef lint
static const char RCSid[] = "$Id: srcdraw.c,v 2.21 2020/05/14 20:58:03 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 "otspecial.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 */
RREAL a[2],
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;
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;
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 */
RREAL vl[][2],
int nv,
RREAL cv[2] /* return value */
)
{
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 */
RREAL vl[][2],
int nv
)
{
double a;
RREAL v0[2], v1[2];
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;
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
)
{
SPLIST *spn;
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}};
SRCREC *s = source + sn;
FVECT ap, ip;
RREAL pt[6][2];
int dir;
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];
}
}
/* find image point */
if (viewloc(ip, &ourview, ap) != VL_GOOD)
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];
}
/* find image point */
if (viewloc(ip, &ourview, ap) != VL_GOOD)
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 */
void
init_drawsources(
int rad /* source sample size */
)
{
RREAL spoly[MAXVERT][2];
int nsv;
SPLIST *sp;
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);
}
}
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;
SPLIST *sp;
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.rxt < 0.99*zbf[y-y0][x-x0]) {
zbf[y-y0][x-x0] = sr.rxt;
} 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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