src/hd/rhpict2.c

/* Copyright (c) 1999 Silicon Graphics, Inc. */

#ifndef lint
static char SCCSid[] = "$SunId$ SGI";
#endif

/*
 * Rendering routines for rhpict.
 */

#include "holo.h"
#include "view.h"

#ifndef DEPS
#define DEPS            0.02    /* depth epsilon */
#endif
#ifndef PEPS
#define PEPS            0.04    /* pixel value epsilon */
#endif
#ifndef MAXRAD
#define MAXRAD          64      /* maximum kernel radius */
#endif
#ifndef NNEIGH
#define NNEIGH          7       /* find this many neighbors */
#endif

#define NINF            16382

#define MAXRAD2         (MAXRAD*MAXRAD+1)

#define G0NORM          0.286   /* ground zero normalization (1/x integral) */

#ifndef FL4OP
#define FL4OP(f,i,op)   ((f)[(i)>>5] op (1L<<((i)&0x1f)))
#define CHK4(f,i)       FL4OP(f,i,&)
#define SET4(f,i)       FL4OP(f,i,|=)
#define CLR4(f,i)       FL4OP(f,i,&=~)
#define TGL4(f,i)       FL4OP(f,i,^=)
#define FL4NELS(n)      (((n)+0x1f)>>5)
#define CLR4ALL(f,n)    bzero((char *)(f),FL4NELS(n)*sizeof(int4))
#endif

static int4     *pixFlags;      /* pixel occupancy flags */
static float    pixWeight[MAXRAD2];     /* pixel weighting function */
static short    isqrttab[MAXRAD2];      /* integer square root table */

#define isqrt(i2)       ((int)isqrttab[(int)(i2)])

extern VIEW     myview;         /* current output view */
extern COLOR    *mypixel;       /* pixels being rendered */
extern float    *myweight;      /* weights (used to compute final pixels) */
extern float    *mydepth;       /* depth values (visibility culling) */
extern int      hres, vres;     /* current horizontal and vertical res. */


pixBeam(bp, hb)                 /* render a particular beam */
BEAM    *bp;
register HDBEAMI        *hb;
{
        GCOORD  gc[2];
        register RAYVAL *rv;
        FVECT   rorg, rdir, wp, ip;
        double  d, prox;
        COLOR   col;
        int     n;
        register int4   p;

        if (!hdbcoord(gc, hb->h, hb->b))
                error(CONSISTENCY, "bad beam in render_beam");
        for (n = bp->nrm, rv = hdbray(bp); n--; rv++) {
                                                /* reproject each sample */
                hdray(rorg, rdir, hb->h, gc, rv->r);
                if (rv->d < DCINF) {
                        d = hddepth(hb->h, rv->d);
                        VSUM(wp, rorg, rdir, d);
                        VSUB(ip, wp, myview.vp);
                        d = DOT(ip,rdir);
                        prox = d*d/DOT(ip,ip);  /* cos(diff_angle)^32 */
                        prox *= prox; prox *= prox; prox *= prox; prox *= prox;
                } else {
                        if (myview.type == VT_PAR || myview.vaft > FTINY)
                                continue;               /* inf. off view */
                        VSUM(wp, myview.vp, rdir, FHUGE);
                        prox = 1.;
                }
                viewloc(ip, &myview, wp);       /* frustum clipping */
                if (ip[2] < 0.)
                        continue;
                if (ip[0] < 0. || ip[0] >= 1.)
                        continue;
                if (ip[1] < 0. || ip[1] >= 1.)
                        continue;
                if (myview.vaft > FTINY && ip[2] > myview.vaft - myview.vfore)
                        continue;               /* not exact for VT_PER */
                p = (int)(ip[1]*vres)*hres + (int)(ip[0]*hres);
                if (mydepth[p] > FTINY) {       /* check depth */
                        if (ip[2] > mydepth[p]*(1.+DEPS))
                                continue;
                        if (ip[2] < mydepth[p]*(1.-DEPS)) {
                                setcolor(mypixel[p], 0., 0., 0.);
                                myweight[p] = 0.;
                        }
                }
                colr_color(col, rv->v);
                scalecolor(col, prox);
                addcolor(mypixel[p], col);
                myweight[p] += prox;
                mydepth[p] = ip[2];
        }
}


int
kill_occl(h, v, nl, n)          /* check for occlusion errors */
int     h, v;
register short  nl[NNEIGH][2];
int     n;
{
        short   forequad[2][2];
        int     d;
        register int4   i, p;

        if (n <= 0) {
#ifdef DEBUG
                error(WARNING, "neighborless sample in kill_occl");
#endif
                return(1);
        }
        p = v*hres + h;
        forequad[0][0] = forequad[0][1] = forequad[1][0] = forequad[1][1] = 0;
        for (i = n; i--; ) {
                d = (h-nl[i][0])*(h-nl[i][0]) + (v-nl[i][1])*(v-nl[i][1]);
                d = isqrt(d);
                if (mydepth[nl[i][1]*hres+nl[i][0]]*(1.+DEPS*d) < mydepth[p])
                        forequad[nl[i][0]<h][nl[i][1]<v] = 1;
        }
        if (forequad[0][0]+forequad[0][1]+forequad[1][0]+forequad[1][1] > 2) {
                setcolor(mypixel[p], 0., 0., 0.);
                myweight[p] = 0.;       /* occupancy reset afterwards */
        }
        return(1);
}


int
grow_samp(h, v, nl, n)          /* grow sample point appropriately */
int     h, v;
register short  nl[NNEIGH][2];
int     n;
{
        int     dis[NNEIGH], ndis;
        COLOR   mykern[MAXRAD2];
        int4    maxr2;
        double  d;
        register int4   p, r2;
        int     i, r, maxr, h2, v2;

        if (n <= 0)
                return(1);
        p = v*hres + h;                         /* build kernel values */
        maxr2 = (h-nl[n-1][0])*(h-nl[n-1][0]) + (v-nl[n-1][1])*(v-nl[n-1][1]);
        DCHECK(maxr2>=MAXRAD2, CONSISTENCY, "out of range neighbor");
        maxr = isqrt(maxr2);
        for (v2 = 1; v2 <= maxr; v2++)
                for (h2 = 0; h2 <= v2; h2++) {
                        r2 = h2*h2 + v2*v2;
                        if (r2 > maxr2) break;
                        copycolor(mykern[r2], mypixel[p]);
                        scalecolor(mykern[r2], pixWeight[r2]);
                }
        ndis = 0;                               /* find discontinuities */
        for (i = n; i--; ) {
                r2 = (h-nl[i][0])*(h-nl[i][0]) + (v-nl[i][1])*(v-nl[i][1]);
                r = isqrt(r2);
                d = mydepth[nl[i][1]*hres+nl[i][0]] / mydepth[p];
                d = d>=1. ? d-1. : 1.-d;
                if (d > r*DEPS || bigdiff(mypixel[p],
                                mypixel[nl[i][1]*hres+nl[i][0]], r*PEPS))
                        dis[ndis++] = i;
        }
                                                /* stamp out that kernel */
        for (v2 = v-maxr; v2 <= v+maxr; v2++) {
                if (v2 < 0) v2 = 0;
                else if (v2 >= vres) break;
                for (h2 = h-maxr; h2 <= h+maxr; h2++) {
                        if (h2 < 0) h2 = 0;
                        else if (h2 >= hres) break;
                        r2 = (h2-h)*(h2-h) + (v2-v)*(v2-v);
                        if (r2 > maxr2) continue;
                        if (CHK4(pixFlags, v2*hres+h2))
                                continue;       /* occupied */
                        for (i = ndis; i--; ) {
                                r = (h2-nl[dis[i]][0])*(h2-nl[dis[i]][0]) +
                                        (v2-nl[dis[i]][1])*(v2-nl[dis[i]][1]);
                                if (r < r2) break;
                        }
                        if (i >= 0) continue;   /* outside edge */
                        addcolor(mypixel[v2*hres+h2], mykern[r2]);
                        myweight[v2*hres+h2] += pixWeight[r2] * myweight[p];
                }
        }
        return(1);
}


pixFlush()                      /* done with beams -- flush pixel values */
{
        if (pixWeight[0] <= FTINY)
                init_wfunc();           /* initialize weighting function */
        reset_flags();                  /* set occupancy flags */
        meet_neighbors(kill_occl);      /* eliminate occlusion errors */
        reset_flags();                  /* reset occupancy flags */
        meet_neighbors(grow_samp);      /* grow valid samples over image */
        free((char *)pixFlags);         /* free pixel flags */
        pixFlags = NULL;
}


reset_flags()                   /* allocate/set/reset occupancy flags */
{
        register int4   p;

        if (pixFlags == NULL) {
                pixFlags = (int4 *)calloc(FL4NELS(hres*vres), sizeof(int4));
                CHECK(pixFlags==NULL, SYSTEM, "out of memory in reset_flags");
        } else
                CLR4ALL(pixFlags, hres*vres);
        for (p = hres*vres; p--; )
                if (myweight[p] > FTINY)
                        SET4(pixFlags, p);
}


init_wfunc()                    /* initialize weighting function */
{
        register int    i, j;
        register int4   r2;
        register double d;

        for (i = 1; i <= MAXRAD; i++)
                for (j = 0; j <= i; j++) {
                        r2 = i*i + j*j;
                        if (r2 >= MAXRAD2) break;
                        d = sqrt((double)r2);
                        pixWeight[r2] = G0NORM/d;
                        isqrttab[r2] = d + 0.99;
                }
        pixWeight[0] = 1.;
        isqrttab[0] = 0;
}


int
findneigh(nl, h, v, rnl)        /* find NNEIGH neighbors for pixel */
short   nl[NNEIGH][2];
int     h, v;
register short  (*rnl)[NNEIGH];
{
        int     nn = 0;
        int4    d, nd[NNEIGH];
        int     n, hoff;
        register int    h2, n2;

        nd[NNEIGH-1] = MAXRAD2;
        for (hoff = 1; hoff < hres; hoff = (hoff<0) - hoff) {
                h2 = h + hoff;
                if (h2 < 0 | h2 >= hres)
                        continue;
                if ((h2-h)*(h2-h) >= nd[NNEIGH-1])
                        break;
                for (n = 0; n < NNEIGH && rnl[h2][n] < NINF; n++) {
                        d = (h2-h)*(h2-h) + (v-rnl[h2][n])*(v-rnl[h2][n]);
                        if (d >= nd[NNEIGH-1])
                                continue;
                        if (nn < NNEIGH)        /* insert neighbor */
                                nn++;
                        for (n2 = nn; n2--; )   {
                                if (!n2 || d >= nd[n2-1]) {
                                        nd[n2] = d;
                                        nl[n2][0] = h2;
                                        nl[n2][1] = rnl[h2][n];
                                        break;
                                }
                                nd[n2] = nd[n2-1];
                                nl[n2][0] = nl[n2-1][0];
                                nl[n2][1] = nl[n2-1][1];
                        }
                }
        }
        return(nn);
}


meet_neighbors(nf)              /* run through samples and their neighbors */
int     (*nf)();
{
        short   ln[NNEIGH][2];
        int     h, v, n, v2;
        register short  (*rnl)[NNEIGH];
                                        /* initialize bottom row list */
        rnl = (short (*)[NNEIGH])malloc(NNEIGH*sizeof(short)*hres);
        CHECK(rnl==NULL, SYSTEM, "out of memory in meet_neighbors");
        for (h = 0; h < hres; h++) {
                for (n = v = 0; v < vres; v++)
                        if (CHK4(pixFlags, v*hres+h)) {
                                rnl[h][n++] = v;
                                if (n >= NNEIGH)
                                        break;
                        }
                while (n < NNEIGH)
                        rnl[h][n++] = NINF;
        }
        v = 0;                          /* do each row */
        for ( ; ; ) {
                for (h = 0; h < hres; h++) {
                        if (!CHK4(pixFlags, v*hres+h))
                                continue;       /* no one home */
                        n = findneigh(ln, h, v, rnl);
                        (*nf)(h, v, ln, n);     /* call on neighbors */
                }
                if (++v >= vres)                /* reinitialize row list */
                        break;
                for (h = 0; h < hres; h++)
                        for (v2 = rnl[h][NNEIGH-1]+1; v2 < vres; v2++) {
                                if (v2 - v > v - rnl[h][0])
                                        break;          /* not close enough */
                                if (CHK4(pixFlags, v2*hres+h)) {
                                        for (n = 0; n < NNEIGH-1; n++)
                                                rnl[h][n] = rnl[h][n+1];
                                        rnl[h][NNEIGH-1] = v2;
                                }
                        }
        }
        free((char *)rnl);              /* free row list */
}
Revision:	3.5
Committed:	Tue Mar 9 11:41:29 1999 UTC (25 years, 1 month ago) by gwlarson
Content type:	text/plain
Branch:	MAIN
Changes since 3.4:	+9 -6 lines
Log Message:	bug fix in occlusion culling
#	User	Rev	Content
1	gwlarson	3.1	/* Copyright (c) 1999 Silicon Graphics, Inc. */
2
3			#ifndef lint
4			static char SCCSid[] = "$SunId$ SGI";
5			#endif
6
7			/*
8			* Rendering routines for rhpict.
9			*/
10
11			#include "holo.h"
12			#include "view.h"
13
14	gwlarson	3.2	#ifndef DEPS
15	gwlarson	3.3	#define DEPS 0.02 /* depth epsilon */
16	gwlarson	3.2	#endif
17	gwlarson	3.3	#ifndef PEPS
18			#define PEPS 0.04 /* pixel value epsilon */
19			#endif
20	gwlarson	3.2	#ifndef MAXRAD
21			#define MAXRAD 64 /* maximum kernel radius */
22			#endif
23			#ifndef NNEIGH
24			#define NNEIGH 7 /* find this many neighbors */
25			#endif
26
27			#define NINF 16382
28
29			#define MAXRAD2 (MAXRAD*MAXRAD+1)
30
31			#define G0NORM 0.286 /* ground zero normalization (1/x integral) */
32
33			#ifndef FL4OP
34			#define FL4OP(f,i,op) ((f)[(i)>>5] op (1L<<((i)&0x1f)))
35			#define CHK4(f,i) FL4OP(f,i,&)
36			#define SET4(f,i) FL4OP(f,i,\|=)
37			#define CLR4(f,i) FL4OP(f,i,&=~)
38			#define TGL4(f,i) FL4OP(f,i,^=)
39			#define FL4NELS(n) (((n)+0x1f)>>5)
40			#define CLR4ALL(f,n) bzero((char )(f),FL4NELS(n)sizeof(int4))
41			#endif
42
43			static int4 pixFlags; / pixel occupancy flags */
44			static float pixWeight[MAXRAD2]; /* pixel weighting function */
45	gwlarson	3.3	static short isqrttab[MAXRAD2]; /* integer square root table */
46	gwlarson	3.2
47	gwlarson	3.3	#define isqrt(i2) ((int)isqrttab[(int)(i2)])
48
49	gwlarson	3.1	extern VIEW myview; /* current output view */
50			extern COLOR mypixel; / pixels being rendered */
51			extern float myweight; / weights (used to compute final pixels) */
52	gwlarson	3.2	extern float mydepth; / depth values (visibility culling) */
53	gwlarson	3.1	extern int hres, vres; /* current horizontal and vertical res. */
54
55
56	gwlarson	3.2	pixBeam(bp, hb) /* render a particular beam */
57	gwlarson	3.1	BEAM *bp;
58			register HDBEAMI *hb;
59			{
60			GCOORD gc[2];
61			register RAYVAL *rv;
62			FVECT rorg, rdir, wp, ip;
63			double d, prox;
64			COLOR col;
65	gwlarson	3.2	int n;
66			register int4 p;
67	gwlarson	3.1
68			if (!hdbcoord(gc, hb->h, hb->b))
69			error(CONSISTENCY, "bad beam in render_beam");
70			for (n = bp->nrm, rv = hdbray(bp); n--; rv++) {
71			/* reproject each sample */
72			hdray(rorg, rdir, hb->h, gc, rv->r);
73			if (rv->d < DCINF) {
74			d = hddepth(hb->h, rv->d);
75			VSUM(wp, rorg, rdir, d);
76			VSUB(ip, wp, myview.vp);
77			d = DOT(ip,rdir);
78	gwlarson	3.2	prox = dd/DOT(ip,ip); / cos(diff_angle)^32 */
79			prox = prox; prox = prox; prox = prox; prox = prox;
80	gwlarson	3.1	} else {
81			if (myview.type == VT_PAR \|\| myview.vaft > FTINY)
82			continue; /* inf. off view */
83			VSUM(wp, myview.vp, rdir, FHUGE);
84	gwlarson	3.2	prox = 1.;
85	gwlarson	3.1	}
86			viewloc(ip, &myview, wp); /* frustum clipping */
87			if (ip[2] < 0.)
88			continue;
89			if (ip[0] < 0. \|\| ip[0] >= 1.)
90			continue;
91			if (ip[1] < 0. \|\| ip[1] >= 1.)
92			continue;
93			if (myview.vaft > FTINY && ip[2] > myview.vaft - myview.vfore)
94	gwlarson	3.2	continue; /* not exact for VT_PER */
95	gwlarson	3.1	p = (int)(ip[1]vres)hres + (int)(ip[0]*hres);
96	gwlarson	3.2	if (mydepth[p] > FTINY) { /* check depth */
97			if (ip[2] > mydepth[p]*(1.+DEPS))
98			continue;
99			if (ip[2] < mydepth[p]*(1.-DEPS)) {
100			setcolor(mypixel[p], 0., 0., 0.);
101			myweight[p] = 0.;
102			}
103			}
104	gwlarson	3.1	colr_color(col, rv->v);
105	gwlarson	3.2	scalecolor(col, prox);
106	gwlarson	3.1	addcolor(mypixel[p], col);
107	gwlarson	3.2	myweight[p] += prox;
108			mydepth[p] = ip[2];
109	gwlarson	3.1	}
110	gwlarson	3.2	}
111
112
113			int
114			kill_occl(h, v, nl, n) /* check for occlusion errors */
115			int h, v;
116	gwlarson	3.3	register short nl[NNEIGH][2];
117	gwlarson	3.2	int n;
118			{
119			short forequad[2][2];
120			int d;
121	gwlarson	3.3	register int4 i, p;
122	gwlarson	3.2
123	gwlarson	3.5	if (n <= 0) {
124			#ifdef DEBUG
125			error(WARNING, "neighborless sample in kill_occl");
126			#endif
127	gwlarson	3.2	return(1);
128	gwlarson	3.5	}
129	gwlarson	3.3	p = v*hres + h;
130	gwlarson	3.2	forequad[0][0] = forequad[0][1] = forequad[1][0] = forequad[1][1] = 0;
131			for (i = n; i--; ) {
132			d = (h-nl[i][0])(h-nl[i][0]) + (v-nl[i][1])(v-nl[i][1]);
133	gwlarson	3.3	d = isqrt(d);
134			if (mydepth[nl[i][1]hres+nl[i][0]](1.+DEPS*d) < mydepth[p])
135	gwlarson	3.2	forequad[nl[i][0]<h][nl[i][1]<v] = 1;
136			}
137	gwlarson	3.3	if (forequad[0][0]+forequad[0][1]+forequad[1][0]+forequad[1][1] > 2) {
138			setcolor(mypixel[p], 0., 0., 0.);
139			myweight[p] = 0.; /* occupancy reset afterwards */
140	gwlarson	3.2	}
141			return(1);
142			}
143
144
145			int
146			grow_samp(h, v, nl, n) /* grow sample point appropriately */
147			int h, v;
148			register short nl[NNEIGH][2];
149			int n;
150			{
151	gwlarson	3.3	int dis[NNEIGH], ndis;
152	gwlarson	3.2	COLOR mykern[MAXRAD2];
153			int4 maxr2;
154	gwlarson	3.5	double d;
155	gwlarson	3.2	register int4 p, r2;
156	gwlarson	3.3	int i, r, maxr, h2, v2;
157	gwlarson	3.2
158			if (n <= 0)
159			return(1);
160			p = vhres + h; / build kernel values */
161			maxr2 = (h-nl[n-1][0])(h-nl[n-1][0]) + (v-nl[n-1][1])(v-nl[n-1][1]);
162			DCHECK(maxr2>=MAXRAD2, CONSISTENCY, "out of range neighbor");
163	gwlarson	3.3	maxr = isqrt(maxr2);
164			for (v2 = 1; v2 <= maxr; v2++)
165			for (h2 = 0; h2 <= v2; h2++) {
166			r2 = h2h2 + v2v2;
167			if (r2 > maxr2) break;
168			copycolor(mykern[r2], mypixel[p]);
169			scalecolor(mykern[r2], pixWeight[r2]);
170			}
171			ndis = 0; /* find discontinuities */
172			for (i = n; i--; ) {
173			r2 = (h-nl[i][0])(h-nl[i][0]) + (v-nl[i][1])(v-nl[i][1]);
174			r = isqrt(r2);
175			d = mydepth[nl[i][1]*hres+nl[i][0]] / mydepth[p];
176			d = d>=1. ? d-1. : 1.-d;
177			if (d > r*DEPS \|\| bigdiff(mypixel[p],
178			mypixel[nl[i][1]hres+nl[i][0]], rPEPS))
179			dis[ndis++] = i;
180	gwlarson	3.2	}
181	gwlarson	3.3	/* stamp out that kernel */
182	gwlarson	3.2	for (v2 = v-maxr; v2 <= v+maxr; v2++) {
183	gwlarson	3.3	if (v2 < 0) v2 = 0;
184			else if (v2 >= vres) break;
185	gwlarson	3.2	for (h2 = h-maxr; h2 <= h+maxr; h2++) {
186	gwlarson	3.3	if (h2 < 0) h2 = 0;
187			else if (h2 >= hres) break;
188			r2 = (h2-h)(h2-h) + (v2-v)(v2-v);
189	gwlarson	3.2	if (r2 > maxr2) continue;
190			if (CHK4(pixFlags, v2*hres+h2))
191			continue; /* occupied */
192	gwlarson	3.3	for (i = ndis; i--; ) {
193			r = (h2-nl[dis[i]][0])*(h2-nl[dis[i]][0]) +
194			(v2-nl[dis[i]][1])*(v2-nl[dis[i]][1]);
195			if (r < r2) break;
196			}
197			if (i >= 0) continue; /* outside edge */
198	gwlarson	3.2	addcolor(mypixel[v2*hres+h2], mykern[r2]);
199	gwlarson	3.5	myweight[v2hres+h2] += pixWeight[r2] myweight[p];
200	gwlarson	3.2	}
201			}
202			return(1);
203			}
204
205
206			pixFlush() /* done with beams -- flush pixel values */
207			{
208	gwlarson	3.5	if (pixWeight[0] <= FTINY)
209			init_wfunc(); /* initialize weighting function */
210	gwlarson	3.2	reset_flags(); /* set occupancy flags */
211			meet_neighbors(kill_occl); /* eliminate occlusion errors */
212			reset_flags(); /* reset occupancy flags */
213			meet_neighbors(grow_samp); /* grow valid samples over image */
214			free((char )pixFlags); / free pixel flags */
215			pixFlags = NULL;
216			}
217
218
219			reset_flags() /* allocate/set/reset occupancy flags */
220			{
221	gwlarson	3.4	register int4 p;
222	gwlarson	3.2
223			if (pixFlags == NULL) {
224			pixFlags = (int4 )calloc(FL4NELS(hresvres), sizeof(int4));
225			CHECK(pixFlags==NULL, SYSTEM, "out of memory in reset_flags");
226			} else
227			CLR4ALL(pixFlags, hres*vres);
228			for (p = hres*vres; p--; )
229			if (myweight[p] > FTINY)
230			SET4(pixFlags, p);
231	gwlarson	3.4	}
232
233
234			init_wfunc() /* initialize weighting function */
235			{
236			register int i, j;
237			register int4 r2;
238			register double d;
239
240			for (i = 1; i <= MAXRAD; i++)
241			for (j = 0; j <= i; j++) {
242			r2 = ii + jj;
243			if (r2 >= MAXRAD2) break;
244			d = sqrt((double)r2);
245			pixWeight[r2] = G0NORM/d;
246			isqrttab[r2] = d + 0.99;
247			}
248			pixWeight[0] = 1.;
249			isqrttab[0] = 0;
250	gwlarson	3.2	}
251
252
253			int
254			findneigh(nl, h, v, rnl) /* find NNEIGH neighbors for pixel */
255			short nl[NNEIGH][2];
256			int h, v;
257			register short (*rnl)[NNEIGH];
258			{
259			int nn = 0;
260	gwlarson	3.3	int4 d, nd[NNEIGH];
261	gwlarson	3.2	int n, hoff;
262			register int h2, n2;
263
264	gwlarson	3.3	nd[NNEIGH-1] = MAXRAD2;
265	gwlarson	3.2	for (hoff = 1; hoff < hres; hoff = (hoff<0) - hoff) {
266			h2 = h + hoff;
267			if (h2 < 0 \| h2 >= hres)
268			continue;
269	gwlarson	3.3	if ((h2-h)*(h2-h) >= nd[NNEIGH-1])
270	gwlarson	3.2	break;
271			for (n = 0; n < NNEIGH && rnl[h2][n] < NINF; n++) {
272			d = (h2-h)(h2-h) + (v-rnl[h2][n])(v-rnl[h2][n]);
273	gwlarson	3.3	if (d >= nd[NNEIGH-1])
274	gwlarson	3.2	continue;
275	gwlarson	3.3	if (nn < NNEIGH) /* insert neighbor */
276			nn++;
277			for (n2 = nn; n2--; ) {
278	gwlarson	3.2	if (!n2 \|\| d >= nd[n2-1]) {
279			nd[n2] = d;
280			nl[n2][0] = h2;
281			nl[n2][1] = rnl[h2][n];
282			break;
283			}
284			nd[n2] = nd[n2-1];
285			nl[n2][0] = nl[n2-1][0];
286			nl[n2][1] = nl[n2-1][1];
287			}
288			}
289			}
290			return(nn);
291			}
292
293
294			meet_neighbors(nf) /* run through samples and their neighbors */
295			int (*nf)();
296			{
297			short ln[NNEIGH][2];
298			int h, v, n, v2;
299			register short (*rnl)[NNEIGH];
300			/* initialize bottom row list */
301			rnl = (short ()[NNEIGH])malloc(NNEIGHsizeof(short)*hres);
302			CHECK(rnl==NULL, SYSTEM, "out of memory in meet_neighbors");
303			for (h = 0; h < hres; h++) {
304			for (n = v = 0; v < vres; v++)
305			if (CHK4(pixFlags, v*hres+h)) {
306			rnl[h][n++] = v;
307			if (n >= NNEIGH)
308			break;
309			}
310			while (n < NNEIGH)
311			rnl[h][n++] = NINF;
312			}
313			v = 0; /* do each row */
314			for ( ; ; ) {
315			for (h = 0; h < hres; h++) {
316			if (!CHK4(pixFlags, v*hres+h))
317			continue; /* no one home */
318			n = findneigh(ln, h, v, rnl);
319			(nf)(h, v, ln, n); / call on neighbors */
320			}
321			if (++v >= vres) /* reinitialize row list */
322			break;
323			for (h = 0; h < hres; h++)
324			for (v2 = rnl[h][NNEIGH-1]+1; v2 < vres; v2++) {
325			if (v2 - v > v - rnl[h][0])
326			break; /* not close enough */
327			if (CHK4(pixFlags, v2*hres+h)) {
328			for (n = 0; n < NNEIGH-1; n++)
329			rnl[h][n] = rnl[h][n+1];
330			rnl[h][NNEIGH-1] = v2;
331			}
332			}
333			}
334			free((char )rnl); / free row list */
335	gwlarson	3.1	}