1 |
greg |
2.1 |
#ifndef lint |
2 |
greg |
2.14 |
static const char RCSid[] = "$Id: interp2d.c,v 2.13 2013/02/16 00:41:12 greg Exp $"; |
3 |
greg |
2.1 |
#endif |
4 |
|
|
/* |
5 |
|
|
* General interpolation method for unstructured values on 2-D plane. |
6 |
|
|
* |
7 |
|
|
* G.Ward Feb 2013 |
8 |
|
|
*/ |
9 |
|
|
|
10 |
|
|
#include "copyright.h" |
11 |
|
|
|
12 |
greg |
2.4 |
/*************************************************************** |
13 |
greg |
2.1 |
* This is a general method for 2-D interpolation similar to |
14 |
|
|
* radial basis functions but allowing for a good deal of local |
15 |
|
|
* anisotropy in the point distribution. Each sample point |
16 |
|
|
* is examined to determine the closest neighboring samples in |
17 |
|
|
* each of NI2DIR surrounding directions. To speed this |
18 |
greg |
2.4 |
* calculation, we sort the data into half-planes and apply |
19 |
|
|
* simple tests to see which neighbor is closest in each |
20 |
greg |
2.7 |
* angular slice. Once we have our approximate neighborhood |
21 |
greg |
2.3 |
* for a sample, we can use it in a modified Gaussian weighting |
22 |
greg |
2.4 |
* with allowing local anisotropy. Harmonic weighting is added |
23 |
greg |
2.3 |
* to reduce the influence of distant neighbors. This yields a |
24 |
|
|
* smooth interpolation regardless of how the sample points are |
25 |
greg |
2.4 |
* initially distributed. Evaluation is accelerated by use of |
26 |
greg |
2.13 |
* a fast approximation to the atan2(y,x) function and a low-res |
27 |
|
|
* map indicating where sample weights are significant. |
28 |
greg |
2.4 |
****************************************************************/ |
29 |
greg |
2.1 |
|
30 |
|
|
#include <stdio.h> |
31 |
|
|
#include <stdlib.h> |
32 |
|
|
#include "rtmath.h" |
33 |
|
|
#include "interp2d.h" |
34 |
|
|
|
35 |
greg |
2.4 |
#define DECODE_DIA(ip,ed) ((ip)->dmin*(1. + .5*(ed))) |
36 |
|
|
#define ENCODE_DIA(ip,d) ((int)(2.*(d)/(ip)->dmin) - 2) |
37 |
greg |
2.1 |
|
38 |
|
|
/* Sample order (private) */ |
39 |
|
|
typedef struct { |
40 |
|
|
int si; /* sample index */ |
41 |
|
|
float dm; /* distance measure in this direction */ |
42 |
|
|
} SAMPORD; |
43 |
|
|
|
44 |
greg |
2.13 |
/* private routine to encode sample diameter with range checks */ |
45 |
|
|
static int |
46 |
|
|
encode_diameter(const INTERP2 *ip, double d) |
47 |
|
|
{ |
48 |
|
|
const int ed = ENCODE_DIA(ip, d); |
49 |
|
|
|
50 |
|
|
if (ed <= 0) |
51 |
|
|
return(0); |
52 |
|
|
if (ed >= 0xffff) |
53 |
|
|
return(0xffff); |
54 |
|
|
return(ed); |
55 |
|
|
} |
56 |
|
|
|
57 |
greg |
2.2 |
/* Allocate a new set of interpolation samples (caller assigns spt[] array) */ |
58 |
greg |
2.1 |
INTERP2 * |
59 |
|
|
interp2_alloc(int nsamps) |
60 |
|
|
{ |
61 |
|
|
INTERP2 *nip; |
62 |
|
|
|
63 |
|
|
if (nsamps <= 1) |
64 |
|
|
return(NULL); |
65 |
|
|
|
66 |
|
|
nip = (INTERP2 *)malloc(sizeof(INTERP2) + sizeof(float)*2*(nsamps-1)); |
67 |
|
|
if (nip == NULL) |
68 |
|
|
return(NULL); |
69 |
|
|
|
70 |
|
|
nip->ns = nsamps; |
71 |
greg |
2.4 |
nip->dmin = 1; /* default minimum diameter */ |
72 |
greg |
2.1 |
nip->smf = NI2DSMF; /* default smoothing factor */ |
73 |
greg |
2.4 |
nip->da = NULL; |
74 |
greg |
2.1 |
/* caller must assign spt[] array */ |
75 |
|
|
return(nip); |
76 |
|
|
} |
77 |
|
|
|
78 |
greg |
2.2 |
/* Resize interpolation array (caller must assign any new values) */ |
79 |
|
|
INTERP2 * |
80 |
|
|
interp2_realloc(INTERP2 *ip, int nsamps) |
81 |
|
|
{ |
82 |
|
|
if (ip == NULL) |
83 |
|
|
return(interp2_alloc(nsamps)); |
84 |
|
|
if (nsamps <= 1) { |
85 |
|
|
interp2_free(ip); |
86 |
|
|
return(NULL); |
87 |
|
|
} |
88 |
greg |
2.8 |
if (nsamps == ip->ns) |
89 |
greg |
2.2 |
return(ip); |
90 |
greg |
2.4 |
if (ip->da != NULL) { /* will need to recompute distribution */ |
91 |
|
|
free(ip->da); |
92 |
|
|
ip->da = NULL; |
93 |
greg |
2.2 |
} |
94 |
|
|
ip = (INTERP2 *)realloc(ip, sizeof(INTERP2)+sizeof(float)*2*(nsamps-1)); |
95 |
|
|
if (ip == NULL) |
96 |
|
|
return(NULL); |
97 |
|
|
ip->ns = nsamps; |
98 |
|
|
return(ip); |
99 |
|
|
} |
100 |
|
|
|
101 |
greg |
2.5 |
/* Set minimum distance under which samples will start to merge */ |
102 |
|
|
void |
103 |
|
|
interp2_spacing(INTERP2 *ip, double mind) |
104 |
|
|
{ |
105 |
|
|
if (mind <= 0) |
106 |
|
|
return; |
107 |
greg |
2.7 |
if ((.998*ip->dmin <= mind) & (mind <= 1.002*ip->dmin)) |
108 |
greg |
2.5 |
return; |
109 |
|
|
if (ip->da != NULL) { /* will need to recompute distribution */ |
110 |
|
|
free(ip->da); |
111 |
|
|
ip->da = NULL; |
112 |
|
|
} |
113 |
|
|
ip->dmin = mind; |
114 |
|
|
} |
115 |
|
|
|
116 |
greg |
2.12 |
/* Compute unnormalized weight for a position relative to a sample */ |
117 |
|
|
double |
118 |
|
|
interp2_wti(INTERP2 *ip, const int i, double x, double y) |
119 |
|
|
{ |
120 |
|
|
double dir, rd, r2, d2; |
121 |
|
|
int ri; |
122 |
|
|
/* get relative direction */ |
123 |
|
|
x -= ip->spt[i][0]; |
124 |
|
|
y -= ip->spt[i][1]; |
125 |
|
|
dir = atan2a(y, x); |
126 |
|
|
dir += 2.*PI*(dir < 0); |
127 |
|
|
/* linear radius interpolation */ |
128 |
|
|
rd = dir * (NI2DIR/2./PI); |
129 |
|
|
ri = (int)rd; |
130 |
|
|
rd -= (double)ri; |
131 |
|
|
rd = (1.-rd)*ip->da[i].dia[ri] + rd*ip->da[i].dia[(ri+1)%NI2DIR]; |
132 |
|
|
rd = ip->smf * DECODE_DIA(ip, rd); |
133 |
|
|
r2 = 2.*rd*rd; |
134 |
|
|
d2 = x*x + y*y; |
135 |
|
|
if (d2 > 21.*r2) /* result would be < 1e-9 */ |
136 |
|
|
return(.0); |
137 |
|
|
/* Gaussian times harmonic weighting */ |
138 |
|
|
return( exp(-d2/r2) * ip->dmin/(ip->dmin + sqrt(d2)) ); |
139 |
|
|
} |
140 |
|
|
|
141 |
|
|
/* private call to get grid flag index */ |
142 |
|
|
static int |
143 |
|
|
interp2_flagpos(int fgi[2], INTERP2 *ip, double x, double y) |
144 |
|
|
{ |
145 |
|
|
int inbounds = 0; |
146 |
|
|
|
147 |
|
|
if (ip == NULL) /* paranoia */ |
148 |
|
|
return(-1); |
149 |
|
|
/* need to compute interpolant? */ |
150 |
|
|
if (ip->da == NULL && !interp2_analyze(ip)) |
151 |
|
|
return(-1); |
152 |
|
|
/* get x & y grid positions */ |
153 |
|
|
fgi[0] = (x - ip->smin[0]) * NI2DIM / (ip->smax[0] - ip->smin[0]); |
154 |
|
|
|
155 |
|
|
if (fgi[0] >= NI2DIM) |
156 |
|
|
fgi[0] = NI2DIM-1; |
157 |
|
|
else if (fgi[0] < 0) |
158 |
|
|
fgi[0] = 0; |
159 |
|
|
else |
160 |
|
|
++inbounds; |
161 |
|
|
|
162 |
|
|
fgi[1] = (y - ip->smin[1]) * NI2DIM / (ip->smax[1] - ip->smin[1]); |
163 |
|
|
|
164 |
|
|
if (fgi[1] >= NI2DIM) |
165 |
|
|
fgi[1] = NI2DIM-1; |
166 |
|
|
else if (fgi[1] < 0) |
167 |
|
|
fgi[1] = 0; |
168 |
|
|
else |
169 |
|
|
++inbounds; |
170 |
|
|
|
171 |
|
|
return(inbounds == 2); |
172 |
|
|
} |
173 |
|
|
|
174 |
|
|
#define setflg(fl,xi,yi) ((fl)[yi] |= 1<<(xi)) |
175 |
|
|
|
176 |
|
|
#define chkflg(fl,xi,yi) ((fl)[yi]>>(xi) & 1) |
177 |
|
|
|
178 |
|
|
/* private flood function to determine sample influence */ |
179 |
|
|
static void |
180 |
|
|
influence_flood(INTERP2 *ip, const int i, unsigned short visited[NI2DIM], |
181 |
|
|
int xfi, int yfi) |
182 |
|
|
{ |
183 |
|
|
double gx = (xfi+.5)*(1./NI2DIM)*(ip->smax[0] - ip->smin[0]) + |
184 |
|
|
ip->smin[0]; |
185 |
|
|
double gy = (yfi+.5)*(1./NI2DIM)*(ip->smax[1] - ip->smin[1]) + |
186 |
|
|
ip->smin[1]; |
187 |
|
|
double dx = gx - ip->spt[i][0]; |
188 |
|
|
double dy = gy - ip->spt[i][1]; |
189 |
|
|
|
190 |
|
|
setflg(visited, xfi, yfi); |
191 |
|
|
|
192 |
|
|
if (dx*dx + dy*dy > 2.*ip->grid2 && interp2_wti(ip, i, gx, gy) <= 1e-7) |
193 |
|
|
return; |
194 |
|
|
|
195 |
|
|
setflg(ip->da[i].infl, xfi, yfi); |
196 |
|
|
|
197 |
|
|
if (xfi > 0 && !chkflg(visited, xfi-1, yfi)) |
198 |
|
|
influence_flood(ip, i, visited, xfi-1, yfi); |
199 |
|
|
|
200 |
|
|
if (yfi > 0 && !chkflg(visited, xfi, yfi-1)) |
201 |
|
|
influence_flood(ip, i, visited, xfi, yfi-1); |
202 |
|
|
|
203 |
|
|
if (xfi < NI2DIM-1 && !chkflg(visited, xfi+1, yfi)) |
204 |
|
|
influence_flood(ip, i, visited, xfi+1, yfi); |
205 |
|
|
|
206 |
|
|
if (yfi < NI2DIM-1 && !chkflg(visited, xfi, yfi+1)) |
207 |
|
|
influence_flood(ip, i, visited, xfi, yfi+1); |
208 |
|
|
} |
209 |
|
|
|
210 |
greg |
2.13 |
/* private call to compute sample influence maps */ |
211 |
|
|
static void |
212 |
|
|
map_influence(INTERP2 *ip) |
213 |
|
|
{ |
214 |
|
|
unsigned short visited[NI2DIM]; |
215 |
|
|
int fgi[2]; |
216 |
|
|
int i, j; |
217 |
|
|
|
218 |
|
|
for (i = ip->ns; i--; ) { |
219 |
|
|
for (j = NI2DIM; j--; ) { |
220 |
|
|
ip->da[i].infl[j] = 0; |
221 |
|
|
visited[j] = 0; |
222 |
|
|
} |
223 |
|
|
interp2_flagpos(fgi, ip, ip->spt[i][0], ip->spt[i][1]); |
224 |
|
|
|
225 |
|
|
influence_flood(ip, i, visited, fgi[0], fgi[1]); |
226 |
|
|
} |
227 |
|
|
} |
228 |
|
|
|
229 |
|
|
/* Modify smoothing parameter by the given factor */ |
230 |
|
|
void |
231 |
|
|
interp2_smooth(INTERP2 *ip, double sf) |
232 |
|
|
{ |
233 |
|
|
float old_smf = ip->smf; |
234 |
|
|
|
235 |
|
|
if ((ip->smf *= sf) < NI2DSMF) |
236 |
|
|
ip->smf = NI2DSMF; |
237 |
|
|
/* need to recompute influence maps? */ |
238 |
|
|
if (ip->da != NULL && (old_smf*.85 > ip->smf) | |
239 |
|
|
(ip->smf > old_smf*1.15)) |
240 |
|
|
map_influence(ip); |
241 |
|
|
} |
242 |
|
|
|
243 |
|
|
/* private call-back to sort position index */ |
244 |
|
|
static int |
245 |
|
|
cmp_spos(const void *p1, const void *p2) |
246 |
|
|
{ |
247 |
|
|
const SAMPORD *so1 = (const SAMPORD *)p1; |
248 |
|
|
const SAMPORD *so2 = (const SAMPORD *)p2; |
249 |
|
|
|
250 |
|
|
if (so1->dm > so2->dm) |
251 |
|
|
return 1; |
252 |
|
|
if (so1->dm < so2->dm) |
253 |
|
|
return -1; |
254 |
|
|
return 0; |
255 |
|
|
} |
256 |
|
|
|
257 |
|
|
/* private routine to order samples in a particular direction */ |
258 |
|
|
static void |
259 |
|
|
sort_samples(SAMPORD *sord, const INTERP2 *ip, double ang) |
260 |
|
|
{ |
261 |
|
|
const double cosd = cos(ang); |
262 |
|
|
const double sind = sin(ang); |
263 |
|
|
int i; |
264 |
|
|
|
265 |
|
|
for (i = ip->ns; i--; ) { |
266 |
|
|
sord[i].si = i; |
267 |
|
|
sord[i].dm = cosd*ip->spt[i][0] + sind*ip->spt[i][1]; |
268 |
|
|
} |
269 |
greg |
2.14 |
qsort(sord, ip->ns, sizeof(SAMPORD), cmp_spos); |
270 |
greg |
2.13 |
} |
271 |
|
|
|
272 |
greg |
2.2 |
/* (Re)compute anisotropic basis function interpolant (normally automatic) */ |
273 |
|
|
int |
274 |
|
|
interp2_analyze(INTERP2 *ip) |
275 |
greg |
2.1 |
{ |
276 |
|
|
SAMPORD *sortord; |
277 |
greg |
2.2 |
int *rightrndx, *leftrndx, *endrndx; |
278 |
greg |
2.13 |
int i, bd; |
279 |
greg |
2.1 |
/* sanity checks */ |
280 |
greg |
2.10 |
if (ip == NULL) |
281 |
|
|
return(0); |
282 |
|
|
if (ip->da != NULL) { /* free previous data if any */ |
283 |
|
|
free(ip->da); |
284 |
|
|
ip->da = NULL; |
285 |
|
|
} |
286 |
|
|
if ((ip->ns <= 1) | (ip->dmin <= 0)) |
287 |
greg |
2.1 |
return(0); |
288 |
greg |
2.10 |
/* compute sample domain */ |
289 |
|
|
ip->smin[0] = ip->smin[1] = FHUGE; |
290 |
greg |
2.11 |
ip->smax[0] = ip->smax[1] = -FHUGE; |
291 |
greg |
2.10 |
for (i = ip->ns; i--; ) { |
292 |
greg |
2.12 |
if (ip->spt[i][0] < ip->smin[0]) ip->smin[0] = ip->spt[i][0]; |
293 |
|
|
if (ip->spt[i][0] > ip->smax[0]) ip->smax[0] = ip->spt[i][0]; |
294 |
|
|
if (ip->spt[i][1] < ip->smin[1]) ip->smin[1] = ip->spt[i][1]; |
295 |
|
|
if (ip->spt[i][1] > ip->smax[1]) ip->smax[1] = ip->spt[i][1]; |
296 |
greg |
2.1 |
} |
297 |
greg |
2.11 |
ip->grid2 = ((ip->smax[0]-ip->smin[0])*(ip->smax[0]-ip->smin[0]) + |
298 |
|
|
(ip->smax[1]-ip->smin[1])*(ip->smax[1]-ip->smin[1])) * |
299 |
|
|
(1./NI2DIM/NI2DIM); |
300 |
greg |
2.10 |
if (ip->grid2 <= FTINY*ip->dmin*ip->dmin) |
301 |
|
|
return(0); |
302 |
|
|
/* allocate analysis data */ |
303 |
greg |
2.13 |
ip->da = (struct interp2_samp *)malloc( |
304 |
|
|
sizeof(struct interp2_samp)*ip->ns ); |
305 |
greg |
2.10 |
if (ip->da == NULL) |
306 |
|
|
return(0); |
307 |
greg |
2.12 |
/* allocate temporary arrays */ |
308 |
greg |
2.1 |
sortord = (SAMPORD *)malloc(sizeof(SAMPORD)*ip->ns); |
309 |
|
|
rightrndx = (int *)malloc(sizeof(int)*ip->ns); |
310 |
|
|
leftrndx = (int *)malloc(sizeof(int)*ip->ns); |
311 |
greg |
2.2 |
endrndx = (int *)malloc(sizeof(int)*ip->ns); |
312 |
|
|
if ((sortord == NULL) | (rightrndx == NULL) | |
313 |
|
|
(leftrndx == NULL) | (endrndx == NULL)) |
314 |
greg |
2.1 |
return(0); |
315 |
|
|
/* run through bidirections */ |
316 |
|
|
for (bd = 0; bd < NI2DIR/2; bd++) { |
317 |
|
|
const double ang = 2.*PI/NI2DIR*bd; |
318 |
greg |
2.2 |
int *sptr; |
319 |
greg |
2.1 |
/* create right reverse index */ |
320 |
greg |
2.2 |
if (bd) { /* re-use from previous iteration? */ |
321 |
|
|
sptr = rightrndx; |
322 |
greg |
2.1 |
rightrndx = leftrndx; |
323 |
|
|
leftrndx = sptr; |
324 |
greg |
2.2 |
} else { /* else sort first half-plane */ |
325 |
|
|
sort_samples(sortord, ip, PI/2. - PI/NI2DIR); |
326 |
|
|
for (i = ip->ns; i--; ) |
327 |
greg |
2.1 |
rightrndx[sortord[i].si] = i; |
328 |
greg |
2.2 |
/* & store reverse order for later */ |
329 |
|
|
for (i = ip->ns; i--; ) |
330 |
|
|
endrndx[sortord[i].si] = ip->ns-1 - i; |
331 |
greg |
2.1 |
} |
332 |
|
|
/* create new left reverse index */ |
333 |
greg |
2.2 |
if (bd == NI2DIR/2 - 1) { /* use order from first iteration? */ |
334 |
|
|
sptr = leftrndx; |
335 |
|
|
leftrndx = endrndx; |
336 |
|
|
endrndx = sptr; |
337 |
|
|
} else { /* else compute new half-plane */ |
338 |
|
|
sort_samples(sortord, ip, ang + (PI/2. + PI/NI2DIR)); |
339 |
|
|
for (i = ip->ns; i--; ) |
340 |
|
|
leftrndx[sortord[i].si] = i; |
341 |
greg |
2.1 |
} |
342 |
|
|
/* sort grid values in this direction */ |
343 |
greg |
2.2 |
sort_samples(sortord, ip, ang); |
344 |
greg |
2.1 |
/* find nearest neighbors each side */ |
345 |
greg |
2.2 |
for (i = ip->ns; i--; ) { |
346 |
greg |
2.3 |
const int ii = sortord[i].si; |
347 |
greg |
2.13 |
int j; |
348 |
greg |
2.3 |
/* preload with large radii */ |
349 |
greg |
2.10 |
ip->da[ii].dia[bd] = |
350 |
|
|
ip->da[ii].dia[bd+NI2DIR/2] = encode_diameter(ip, |
351 |
|
|
.5*(sortord[ip->ns-1].dm - sortord[0].dm)); |
352 |
greg |
2.1 |
for (j = i; ++j < ip->ns; ) /* nearest above */ |
353 |
greg |
2.3 |
if (rightrndx[sortord[j].si] > rightrndx[ii] && |
354 |
|
|
leftrndx[sortord[j].si] < leftrndx[ii]) { |
355 |
greg |
2.10 |
ip->da[ii].dia[bd] = encode_diameter(ip, |
356 |
greg |
2.4 |
sortord[j].dm - sortord[i].dm); |
357 |
greg |
2.1 |
break; |
358 |
|
|
} |
359 |
|
|
for (j = i; j-- > 0; ) /* nearest below */ |
360 |
greg |
2.3 |
if (rightrndx[sortord[j].si] < rightrndx[ii] && |
361 |
|
|
leftrndx[sortord[j].si] > leftrndx[ii]) { |
362 |
greg |
2.10 |
ip->da[ii].dia[bd+NI2DIR/2] = encode_diameter(ip, |
363 |
greg |
2.4 |
sortord[i].dm - sortord[j].dm); |
364 |
greg |
2.1 |
break; |
365 |
|
|
} |
366 |
|
|
} |
367 |
|
|
} |
368 |
greg |
2.12 |
free(sortord); /* release temp arrays */ |
369 |
greg |
2.1 |
free(rightrndx); |
370 |
|
|
free(leftrndx); |
371 |
greg |
2.2 |
free(endrndx); |
372 |
greg |
2.13 |
/* map sample influence areas */ |
373 |
|
|
map_influence(ip); |
374 |
greg |
2.12 |
return(1); /* all done */ |
375 |
greg |
2.11 |
} |
376 |
|
|
|
377 |
greg |
2.1 |
/* Assign full set of normalized weights to interpolate the given position */ |
378 |
|
|
int |
379 |
|
|
interp2_weights(float wtv[], INTERP2 *ip, double x, double y) |
380 |
|
|
{ |
381 |
|
|
double wnorm; |
382 |
greg |
2.11 |
int fgi[2]; |
383 |
greg |
2.1 |
int i; |
384 |
|
|
|
385 |
greg |
2.11 |
if (wtv == NULL) |
386 |
|
|
return(0); |
387 |
|
|
/* get flag position */ |
388 |
greg |
2.12 |
if (interp2_flagpos(fgi, ip, x, y) < 0) |
389 |
greg |
2.1 |
return(0); |
390 |
|
|
|
391 |
|
|
wnorm = 0; /* compute raw weights */ |
392 |
greg |
2.11 |
for (i = ip->ns; i--; ) |
393 |
greg |
2.12 |
if (chkflg(ip->da[i].infl, fgi[0], fgi[1])) { |
394 |
greg |
2.10 |
double wt = interp2_wti(ip, i, x, y); |
395 |
greg |
2.1 |
wtv[i] = wt; |
396 |
|
|
wnorm += wt; |
397 |
greg |
2.12 |
} else |
398 |
|
|
wtv[i] = 0; |
399 |
greg |
2.1 |
if (wnorm <= 0) /* too far from all our samples! */ |
400 |
|
|
return(0); |
401 |
|
|
wnorm = 1./wnorm; /* normalize weights */ |
402 |
|
|
for (i = ip->ns; i--; ) |
403 |
|
|
wtv[i] *= wnorm; |
404 |
|
|
return(ip->ns); /* all done */ |
405 |
|
|
} |
406 |
|
|
|
407 |
|
|
|
408 |
|
|
/* Get normalized weights and indexes for n best samples in descending order */ |
409 |
|
|
int |
410 |
|
|
interp2_topsamp(float wt[], int si[], const int n, INTERP2 *ip, double x, double y) |
411 |
|
|
{ |
412 |
|
|
int nn = 0; |
413 |
greg |
2.11 |
int fgi[2]; |
414 |
greg |
2.1 |
double wnorm; |
415 |
|
|
int i, j; |
416 |
|
|
|
417 |
greg |
2.11 |
if ((n <= 0) | (wt == NULL) | (si == NULL)) |
418 |
|
|
return(0); |
419 |
|
|
/* get flag position */ |
420 |
greg |
2.12 |
if (interp2_flagpos(fgi, ip, x, y) < 0) |
421 |
greg |
2.1 |
return(0); |
422 |
|
|
/* identify top n weights */ |
423 |
greg |
2.11 |
for (i = ip->ns; i--; ) |
424 |
greg |
2.12 |
if (chkflg(ip->da[i].infl, fgi[0], fgi[1])) { |
425 |
greg |
2.10 |
const double wti = interp2_wti(ip, i, x, y); |
426 |
greg |
2.1 |
for (j = nn; j > 0; j--) { |
427 |
greg |
2.3 |
if (wt[j-1] >= wti) |
428 |
greg |
2.1 |
break; |
429 |
|
|
if (j < n) { |
430 |
|
|
wt[j] = wt[j-1]; |
431 |
|
|
si[j] = si[j-1]; |
432 |
|
|
} |
433 |
|
|
} |
434 |
|
|
if (j < n) { /* add/insert sample */ |
435 |
greg |
2.3 |
wt[j] = wti; |
436 |
greg |
2.1 |
si[j] = i; |
437 |
|
|
nn += (nn < n); |
438 |
|
|
} |
439 |
greg |
2.11 |
} |
440 |
greg |
2.3 |
wnorm = 0; /* normalize sample weights */ |
441 |
|
|
for (j = nn; j--; ) |
442 |
|
|
wnorm += wt[j]; |
443 |
greg |
2.1 |
if (wnorm <= 0) |
444 |
|
|
return(0); |
445 |
|
|
wnorm = 1./wnorm; |
446 |
|
|
for (j = nn; j--; ) |
447 |
|
|
wt[j] *= wnorm; |
448 |
|
|
return(nn); /* return actual # samples */ |
449 |
|
|
} |
450 |
|
|
|
451 |
|
|
/* Free interpolant */ |
452 |
|
|
void |
453 |
|
|
interp2_free(INTERP2 *ip) |
454 |
|
|
{ |
455 |
|
|
if (ip == NULL) |
456 |
|
|
return; |
457 |
greg |
2.4 |
if (ip->da != NULL) |
458 |
|
|
free(ip->da); |
459 |
greg |
2.1 |
free(ip); |
460 |
|
|
} |