src/rt/srcdraw.c

#ifndef lint
static const char       RCSid[] = "$Id: srcdraw.c,v 2.10 2003/10/24 05:29:43 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  "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 && ourview.type == VT_PAR)
                        return(0);              /* all or nothing case */
                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--; ) {
                                        /* 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 */
                                w = poly_area(ppoly, npv) * hres * vres;
                                if (w < .95) {          /* subpixel source */
                                        rayorigin(&sr, NULL, SHADOW, 1.0);
                                        sr.rsrc = sp->sn;
                                } else
                                        rayorigin(&sr, NULL, PRIMARY, 1.0);
                                rayvalue(&sr);          /* compute value */
                                if (bright(sr.rcol) <= FTINY)
                                        continue;       /* missed/blocked */
                                                        /* modify pixel */
                                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 */
                                        setcolor(pic[y-y0][x-x0], 0., 0., 0.);
                                scalecolor(sr.rcol, w);
                                scalecolor(pic[y-y0][x-x0], 1.-w);
                                addcolor(pic[y-y0][x-x0], sr.rcol);
                        }
        }
}
Revision:	2.11
Committed:	Tue Mar 30 16:13:01 2004 UTC (21 years, 6 months ago) by schorsch
Content type:	text/plain
Branch:	MAIN
Changes since 2.10:	+87 -56 lines
Log Message:	Continued ANSIfication. There are only bits and pieces left now.
#	User	Rev	Content
1	greg	2.1	#ifndef lint
2	schorsch	2.11	static const char RCSid[] = "$Id: srcdraw.c,v 2.10 2003/10/24 05:29:43 greg Exp $";
3	greg	2.1	#endif
4			/*
5			* Draw small sources into image in case we missed them.
6	greg	2.5	*
7			* External symbols declared in ray.h
8			*/
9
10	greg	2.6	#include "copyright.h"
11	greg	2.1
12			#include "ray.h"
13			#include "view.h"
14			#include "source.h"
15
16
17			#define CLIP_ABOVE 1
18			#define CLIP_BELOW 2
19			#define CLIP_RIGHT 3
20			#define CLIP_LEFT 4
21
22			#define MAXVERT 10
23
24	greg	2.3	typedef struct splist {
25			struct splist next; / next source in list */
26			int sn; /* source number */
27			short nv; /* number of vertices */
28	schorsch	2.7	RREAL vl[3][2]; /* vertex array (last) */
29	greg	2.3	} SPLIST; /* source polygon list */
30	greg	2.1
31	greg	2.3	extern VIEW ourview; /* our view parameters */
32			extern int hres, vres; /* our image resolution */
33			static SPLIST sphead = NULL; / our list of source polys */
34
35	schorsch	2.11	static int inregion(RREAL p[2], double cv, int crit);
36			static void clipregion(RREAL a[2], RREAL b[2], double cv, int crit, RREAL r[2]);
37			static int hp_clip_poly(RREAL vl[][2], int nv, double cv, int crit,
38			RREAL vlo[][2]);
39			static int box_clip_poly(RREAL vl[MAXVERT][2], int nv,
40			double xl, double xr, double yb, double ya, RREAL vlo[MAXVERT][2]);
41			static double minw2(RREAL vl[][2], int nv, double ar2);
42			static void convex_center(RREAL vl[][2], int nv, RREAL cv[2]);
43			static double poly_area(RREAL vl[][2], int nv);
44			static int convex_hull(RREAL vl[][2], int nv, RREAL vlo[][2]);
45			static void spinsert(int sn, RREAL vl[][2], int nv);
46			static int sourcepoly(int sn, RREAL sp[MAXVERT][2]);
47
48	greg	2.3
49	greg	2.1	static int
50	schorsch	2.11	inregion( /* check if vertex is in region */
51			RREAL p[2],
52			double cv,
53			int crit
54			)
55	greg	2.1	{
56			switch (crit) {
57			case CLIP_ABOVE:
58			return(p[1] < cv);
59			case CLIP_BELOW:
60			return(p[1] >= cv);
61			case CLIP_RIGHT:
62			return(p[0] < cv);
63			case CLIP_LEFT:
64			return(p[0] >= cv);
65			}
66			return(-1);
67			}
68
69
70	schorsch	2.11	static void
71			clipregion( /* find intersection with boundary */
72			register RREAL a[2],
73			register RREAL b[2],
74			double cv,
75			int crit,
76			RREAL r[2] /* return value */
77			)
78	greg	2.1	{
79			switch (crit) {
80			case CLIP_ABOVE:
81			case CLIP_BELOW:
82			r[1] = cv;
83			r[0] = a[0] + (cv-a[1])/(b[1]-a[1])*(b[0]-a[0]);
84			return;
85			case CLIP_RIGHT:
86			case CLIP_LEFT:
87			r[0] = cv;
88			r[1] = a[1] + (cv-a[0])/(b[0]-a[0])*(b[1]-a[1]);
89			return;
90			}
91			}
92
93
94			static int
95	schorsch	2.11	hp_clip_poly( /* clip polygon to half-plane */
96			RREAL vl[][2],
97			int nv,
98			double cv,
99			int crit,
100			RREAL vlo[][2] /* return value */
101			)
102	greg	2.1	{
103	schorsch	2.7	RREAL s, p;
104	greg	2.1	register int j, nvo;
105
106			s = vl[nv-1];
107			nvo = 0;
108			for (j = 0; j < nv; j++) {
109			p = vl[j];
110			if (inregion(p, cv, crit)) {
111			if (!inregion(s, cv, crit))
112			clipregion(s, p, cv, crit, vlo[nvo++]);
113			vlo[nvo][0] = p[0]; vlo[nvo++][1] = p[1];
114			} else if (inregion(s, cv, crit))
115			clipregion(s, p, cv, crit, vlo[nvo++]);
116			s = p;
117			}
118			return(nvo);
119			}
120
121
122			static int
123	schorsch	2.11	box_clip_poly( /* clip polygon to box */
124			RREAL vl[MAXVERT][2],
125			int nv,
126			double xl,
127			double xr,
128			double yb,
129			double ya,
130			RREAL vlo[MAXVERT][2] /* return value */
131			)
132	greg	2.1	{
133	schorsch	2.7	RREAL vlt[MAXVERT][2];
134	greg	2.1	int nvt, nvo;
135
136			nvt = hp_clip_poly(vl, nv, yb, CLIP_BELOW, vlt);
137			nvo = hp_clip_poly(vlt, nvt, ya, CLIP_ABOVE, vlo);
138			nvt = hp_clip_poly(vlo, nvo, xl, CLIP_LEFT, vlt);
139			nvo = hp_clip_poly(vlt, nvt, xr, CLIP_RIGHT, vlo);
140
141			return(nvo);
142			}
143
144
145			static double
146	schorsch	2.11	minw2( /* compute square of minimum width */
147			RREAL vl[][2],
148			int nv,
149			double ar2
150			)
151	greg	2.1	{
152			double d2, w2, w2min, w2max;
153	schorsch	2.7	register RREAL p0, p1, *p2;
154	greg	2.1	int i, j;
155			/* find minimum for all widths */
156			w2min = FHUGE;
157			p0 = vl[nv-1];
158			for (i = 0; i < nv; i++) { /* for each edge */
159			p1 = vl[i];
160			d2 = (p1[0]-p0[0])*(p1[0]-p0[0]) +
161			(p1[1]-p0[1])(p1[1]-p0[1])ar2;
162			w2max = 0.; /* find maximum for this side */
163			for (j = 1; j < nv-1; j++) {
164			p2 = vl[(i+j)%nv];
165			w2 = (p1[0]-p0[0])*(p2[1]-p0[1]) -
166			(p1[1]-p0[1])*(p2[0]-p0[0]);
167			w2 = w2w2ar2/d2; /* triangle height squared */
168			if (w2 > w2max)
169			w2max = w2;
170			}
171			if (w2max < w2min) /* global min. based on local max.'s */
172			w2min = w2max;
173			p0 = p1;
174			}
175			return(w2min);
176			}
177
178
179	schorsch	2.11	static void
180			convex_center( /* compute center of convex polygon */
181			register RREAL vl[][2],
182			int nv,
183			RREAL cv[2] /* return value */
184			)
185	greg	2.1	{
186			register int i;
187			/* simple average (suboptimal) */
188			cv[0] = cv[1] = 0.;
189			for (i = 0; i < nv; i++) {
190			cv[0] += vl[i][0];
191			cv[1] += vl[i][1];
192			}
193			cv[0] /= (double)nv;
194			cv[1] /= (double)nv;
195			}
196
197
198			static double
199	schorsch	2.11	poly_area( /* compute area of polygon */
200			register RREAL vl[][2],
201			int nv
202			)
203	greg	2.1	{
204			double a;
205	schorsch	2.7	RREAL v0[2], v1[2];
206	greg	2.1	register int i;
207
208			a = 0.;
209			v0[0] = vl[1][0] - vl[0][0];
210			v0[1] = vl[1][1] - vl[0][1];
211			for (i = 2; i < nv; i++) {
212			v1[0] = vl[i][0] - vl[0][0];
213			v1[1] = vl[i][1] - vl[0][1];
214			a += v0[0]v1[1] - v0[1]v1[0];
215			v0[0] = v1[0]; v0[1] = v1[1];
216			}
217			return(a * (a >= 0. ? .5 : -.5));
218			}
219
220
221			static int
222	schorsch	2.11	convex_hull( /* compute polygon's convex hull */
223			RREAL vl[][2],
224			int nv,
225			RREAL vlo[][2] /* return value */
226			)
227	greg	2.1	{
228			int nvo, nvt;
229	schorsch	2.7	RREAL vlt[MAXVERT][2];
230	greg	2.1	double voa, vta;
231			register int i, j;
232			/* start with original polygon */
233			for (i = nvo = nv; i--; ) {
234			vlo[i][0] = vl[i][0]; vlo[i][1] = vl[i][1];
235			}
236			voa = poly_area(vlo, nvo); /* compute its area */
237			for (i = 0; i < nvo; i++) { /* for each output vertex */
238			for (j = 0; j < i; j++) {
239			vlt[j][0] = vlo[j][0]; vlt[j][1] = vlo[j][1];
240			}
241			nvt = nvo - 1; /* make poly w/o vertex */
242			for (j = i; j < nvt; j++) {
243			vlt[j][0] = vlo[j+1][0]; vlt[j][1] = vlo[j+1][1];
244			}
245			vta = poly_area(vlt, nvt);
246			if (vta >= voa) { /* is simpler poly bigger? */
247			voa = vta; /* then use it */
248			for (j = nvo = nvt; j--; ) {
249			vlo[j][0] = vlt[j][0]; vlo[j][1] = vlt[j][1];
250			}
251			i--; /* next adjust */
252			}
253			}
254			return(nvo);
255			}
256
257
258	schorsch	2.11	static void
259			spinsert( /* insert new source polygon */
260			int sn,
261			RREAL vl[][2],
262			int nv
263			)
264	greg	2.3	{
265			register SPLIST *spn;
266			register int i;
267
268			if (nv < 3)
269			return;
270			if (nv > 3)
271	schorsch	2.7	spn = (SPLIST )malloc(sizeof(SPLIST)+sizeof(RREAL)2*(nv-3));
272	greg	2.3	else
273			spn = (SPLIST *)malloc(sizeof(SPLIST));
274			if (spn == NULL)
275			error(SYSTEM, "out of memory in spinsert");
276			spn->sn = sn;
277			for (i = spn->nv = nv; i--; ) {
278			spn->vl[i][0] = vl[i][0]; spn->vl[i][1] = vl[i][1];
279			}
280			spn->next = sphead; /* push onto global list */
281			sphead = spn;
282			}
283
284
285	schorsch	2.11	static int
286			sourcepoly( /* compute image polygon for source */
287			int sn,
288			RREAL sp[MAXVERT][2]
289			)
290	greg	2.1	{
291	greg	2.9	static short cubeord[8][6] = {{1,3,2,6,4,5},{0,4,5,7,3,2},
292	greg	2.1	{0,1,3,7,6,4},{0,1,5,7,6,2},
293			{0,2,6,7,5,1},{0,4,6,7,3,1},
294			{0,2,3,7,5,4},{1,5,4,6,2,3}};
295			register SRCREC *s = source + sn;
296			FVECT ap, ip;
297	schorsch	2.7	RREAL pt[6][2];
298	greg	2.1	int dir;
299			register int i, j;
300
301			if (s->sflags & (SDISTANT\|SFLAT)) {
302	greg	2.3	if (s->sflags & SDISTANT && ourview.type == VT_PAR)
303	greg	2.1	return(0); /* all or nothing case */
304			if (s->sflags & SFLAT) {
305			for (i = 0; i < 3; i++)
306	greg	2.3	ap[i] = s->sloc[i] - ourview.vp[i];
307	greg	2.1	if (DOT(ap, s->snorm) >= 0.)
308			return(0); /* source faces away */
309			}
310			for (j = 0; j < 4; j++) { /* four corners */
311			for (i = 0; i < 3; i++) {
312			ap[i] = s->sloc[i];
313	schorsch	2.8	if ((j==1)\|(j==2)) ap[i] += s->ss[SU][i];
314	greg	2.1	else ap[i] -= s->ss[SU][i];
315	schorsch	2.8	if ((j==2)\|(j==3)) ap[i] += s->ss[SV][i];
316	greg	2.1	else ap[i] -= s->ss[SV][i];
317			if (s->sflags & SDISTANT) {
318	greg	2.3	ap[i] *= 1. + ourview.vfore;
319			ap[i] += ourview.vp[i];
320	greg	2.1	}
321			}
322	greg	2.3	viewloc(ip, &ourview, ap); /* find image point */
323	greg	2.1	if (ip[2] <= 0.)
324			return(0); /* in front of view */
325			sp[j][0] = ip[0]; sp[j][1] = ip[1];
326			}
327			return(4);
328			}
329			/* identify furthest corner */
330			for (i = 0; i < 3; i++)
331	greg	2.3	ap[i] = s->sloc[i] - ourview.vp[i];
332	greg	2.1	dir = (DOT(ap,s->ss[SU])>0.) \|
333			(DOT(ap,s->ss[SV])>0.)<<1 \|
334			(DOT(ap,s->ss[SW])>0.)<<2 ;
335			/* order vertices based on this */
336			for (j = 0; j < 6; j++) {
337			for (i = 0; i < 3; i++) {
338			ap[i] = s->sloc[i];
339			if (cubeord[dir][j] & 1) ap[i] += s->ss[SU][i];
340			else ap[i] -= s->ss[SU][i];
341			if (cubeord[dir][j] & 2) ap[i] += s->ss[SV][i];
342			else ap[i] -= s->ss[SV][i];
343			if (cubeord[dir][j] & 4) ap[i] += s->ss[SW][i];
344			else ap[i] -= s->ss[SW][i];
345			}
346	greg	2.3	viewloc(ip, &ourview, ap); /* find image point */
347	greg	2.1	if (ip[2] <= 0.)
348			return(0); /* in front of view */
349			pt[j][0] = ip[0]; pt[j][1] = ip[1];
350			}
351			return(convex_hull(pt, 6, sp)); /* make sure it's convex */
352			}
353
354
355	greg	2.3	/* initialize by finding sources smaller than rad */
356	schorsch	2.11	extern void
357			init_drawsources(
358			int rad /* source sample size */
359			)
360	greg	2.3	{
361	schorsch	2.7	RREAL spoly[MAXVERT][2];
362	greg	2.3	int nsv;
363			register SPLIST *sp;
364			register int i;
365			/* free old source list if one */
366			for (sp = sphead; sp != NULL; sp = sphead) {
367			sphead = sp->next;
368	greg	2.5	free((void *)sp);
369	greg	2.3	}
370			/* loop through all sources */
371			for (i = nsources; i--; ) {
372			/* compute image polygon for source */
373			if (!(nsv = sourcepoly(i, spoly)))
374			continue;
375			/* clip to image boundaries */
376			if (!(nsv = box_clip_poly(spoly, nsv, 0., 1., 0., 1., spoly)))
377			continue;
378			/* big enough for standard sampling? */
379			if (minw2(spoly, nsv, ourview.vn2/ourview.hn2) >
380			(double)rad*rad/hres/hres)
381			continue;
382			/* OK, add to our list */
383			spinsert(i, spoly, nsv);
384			}
385			}
386
387	schorsch	2.11	extern void /* add sources smaller than rad to computed subimage */
388			drawsources(
389			COLOR pic[], / subimage pixel value array */
390			float zbf[], / subimage distance array (opt.) */
391			int x0, /* origin and size of subimage */
392			int xsiz,
393			int y0,
394			int ysiz
395			)
396	greg	2.1	{
397	schorsch	2.7	RREAL spoly[MAXVERT][2], ppoly[MAXVERT][2];
398	greg	2.1	int nsv, npv;
399	greg	2.3	int xmin, xmax, ymin, ymax, x, y;
400	schorsch	2.7	RREAL cxy[2];
401	gregl	2.4	double w;
402	greg	2.1	RAY sr;
403	greg	2.3	register SPLIST *sp;
404			register int i;
405			/* check each source in our list */
406			for (sp = sphead; sp != NULL; sp = sp->next) {
407	greg	2.1	/* clip source poly to subimage */
408	greg	2.3	nsv = box_clip_poly(sp->vl, sp->nv,
409			(double)x0/hres, (double)(x0+xsiz)/hres,
410			(double)y0/vres, (double)(y0+ysiz)/vres, spoly);
411	greg	2.1	if (!nsv)
412			continue;
413			/* find common subimage (BBox) */
414			xmin = x0 + xsiz; xmax = x0;
415			ymin = y0 + ysiz; ymax = y0;
416			for (i = 0; i < nsv; i++) {
417	greg	2.3	if ((double)xmin/hres > spoly[i][0])
418			xmin = spoly[i][0]*hres + FTINY;
419			if ((double)xmax/hres < spoly[i][0])
420			xmax = spoly[i][0]*hres - FTINY;
421			if ((double)ymin/vres > spoly[i][1])
422			ymin = spoly[i][1]*vres + FTINY;
423			if ((double)ymax/vres < spoly[i][1])
424			ymax = spoly[i][1]*vres - FTINY;
425	greg	2.1	}
426			/* evaluate each pixel in BBox */
427			for (y = ymin; y <= ymax; y++)
428			for (x = xmin; x <= xmax; x++) {
429			/* subarea for pixel */
430			npv = box_clip_poly(spoly, nsv,
431	greg	2.3	(double)x/hres, (x+1.)/hres,
432			(double)y/vres, (y+1.)/vres,
433			ppoly);
434	greg	2.1	if (!npv)
435			continue; /* no overlap */
436			convex_center(ppoly, npv, cxy);
437	greg	2.3	if ((sr.rmax = viewray(sr.rorg,sr.rdir,&ourview,
438			cxy[0],cxy[1])) < -FTINY)
439	greg	2.1	continue; /* not in view */
440	greg	2.3	if (source[sp->sn].sflags & SSPOT &&
441			spotout(&sr, source[sp->sn].sl.s))
442	greg	2.1	continue; /* outside spot */
443	greg	2.9	w = poly_area(ppoly, npv) * hres * vres;
444			if (w < .95) { /* subpixel source */
445			rayorigin(&sr, NULL, SHADOW, 1.0);
446			sr.rsrc = sp->sn;
447			} else
448			rayorigin(&sr, NULL, PRIMARY, 1.0);
449	greg	2.1	rayvalue(&sr); /* compute value */
450			if (bright(sr.rcol) <= FTINY)
451			continue; /* missed/blocked */
452			/* modify pixel */
453			if (zbf[y-y0] != NULL &&
454	greg	2.10	sr.rt < 0.99*zbf[y-y0][x-x0])
455	greg	2.1	zbf[y-y0][x-x0] = sr.rt;
456	gregl	2.4	else if (!bigdiff(sr.rcol, pic[y-y0][x-x0],
457	greg	2.9	0.01)) /* source sample */
458	gregl	2.4	setcolor(pic[y-y0][x-x0], 0., 0., 0.);
459			scalecolor(sr.rcol, w);
460			scalecolor(pic[y-y0][x-x0], 1.-w);
461	greg	2.1	addcolor(pic[y-y0][x-x0], sr.rcol);
462			}
463			}
464			}