1 |
greg |
2.1 |
#ifndef lint |
2 |
greg |
2.25 |
static const char RCSid[] = "$Id: bsdfrbf.c,v 2.24 2014/03/21 01:04:42 greg Exp $"; |
3 |
greg |
2.1 |
#endif |
4 |
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/* |
5 |
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* Radial basis function representation for BSDF data. |
6 |
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* |
7 |
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* G. Ward |
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*/ |
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10 |
greg |
2.13 |
/**************************************************************** |
11 |
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1) Collect samples into a grid using the Shirley-Chiu |
12 |
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angular mapping from a hemisphere to a square. |
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14 |
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2) Compute an adaptive quadtree by subdividing the grid so that |
15 |
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each leaf node has at least one sample up to as many |
16 |
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samples as fit nicely on a plane to within a certain |
17 |
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MSE tolerance. |
18 |
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19 |
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3) Place one Gaussian lobe at each leaf node in the quadtree, |
20 |
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sizing it to have a radius equal to the leaf size and |
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a volume equal to the energy in that node. |
22 |
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*****************************************************************/ |
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24 |
greg |
2.1 |
#define _USE_MATH_DEFINES |
25 |
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#include <stdio.h> |
26 |
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#include <stdlib.h> |
27 |
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#include <string.h> |
28 |
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#include <math.h> |
29 |
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#include "bsdfrep.h" |
30 |
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31 |
greg |
2.12 |
#ifndef RSCA |
32 |
greg |
2.25 |
#define RSCA 2.0 /* radius scaling factor (empirical) */ |
33 |
greg |
2.9 |
#endif |
34 |
greg |
2.12 |
#ifndef SMOOTH_MSE |
35 |
greg |
2.19 |
#define SMOOTH_MSE 5e-5 /* acceptable mean squared error */ |
36 |
greg |
2.1 |
#endif |
37 |
greg |
2.12 |
#ifndef SMOOTH_MSER |
38 |
greg |
2.18 |
#define SMOOTH_MSER 0.03 /* acceptable relative MSE */ |
39 |
greg |
2.7 |
#endif |
40 |
greg |
2.12 |
#define MAX_RAD (GRIDRES/8) /* maximum lobe radius */ |
41 |
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42 |
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#define RBFALLOCB 10 /* RBF allocation block size */ |
43 |
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44 |
greg |
2.25 |
/* loaded grid or comparison DSFs */ |
45 |
greg |
2.1 |
GRIDVAL dsf_grid[GRIDRES][GRIDRES]; |
46 |
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47 |
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/* Start new DSF input grid */ |
48 |
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void |
49 |
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new_bsdf_data(double new_theta, double new_phi) |
50 |
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{ |
51 |
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if (!new_input_direction(new_theta, new_phi)) |
52 |
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exit(1); |
53 |
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memset(dsf_grid, 0, sizeof(dsf_grid)); |
54 |
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} |
55 |
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56 |
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/* Add BSDF data point */ |
57 |
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void |
58 |
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add_bsdf_data(double theta_out, double phi_out, double val, int isDSF) |
59 |
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{ |
60 |
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FVECT ovec; |
61 |
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int pos[2]; |
62 |
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63 |
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if (!output_orient) /* check output orientation */ |
64 |
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output_orient = 1 - 2*(theta_out > 90.); |
65 |
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else if (output_orient > 0 ^ theta_out < 90.) { |
66 |
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fputs("Cannot handle output angles on both sides of surface\n", |
67 |
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stderr); |
68 |
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exit(1); |
69 |
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} |
70 |
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ovec[2] = sin((M_PI/180.)*theta_out); |
71 |
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ovec[0] = cos((M_PI/180.)*phi_out) * ovec[2]; |
72 |
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ovec[1] = sin((M_PI/180.)*phi_out) * ovec[2]; |
73 |
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ovec[2] = sqrt(1. - ovec[2]*ovec[2]); |
74 |
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|
75 |
greg |
2.21 |
if (!isDSF) |
76 |
greg |
2.1 |
val *= ovec[2]; /* convert from BSDF to DSF */ |
77 |
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78 |
greg |
2.4 |
/* update BSDF histogram */ |
79 |
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if (val < BSDF2BIG*ovec[2] && val > BSDF2SML*ovec[2]) |
80 |
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++bsdf_hist[histndx(val/ovec[2])]; |
81 |
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82 |
greg |
2.1 |
pos_from_vec(pos, ovec); |
83 |
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84 |
greg |
2.20 |
dsf_grid[pos[0]][pos[1]].sum.v += val; |
85 |
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dsf_grid[pos[0]][pos[1]].sum.n++; |
86 |
greg |
2.1 |
} |
87 |
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88 |
greg |
2.11 |
/* Compute minimum BSDF from histogram (does not clear) */ |
89 |
greg |
2.5 |
static void |
90 |
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comp_bsdf_min() |
91 |
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{ |
92 |
greg |
2.17 |
unsigned long cnt, target; |
93 |
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int i; |
94 |
greg |
2.5 |
|
95 |
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cnt = 0; |
96 |
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for (i = HISTLEN; i--; ) |
97 |
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cnt += bsdf_hist[i]; |
98 |
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if (!cnt) { /* shouldn't happen */ |
99 |
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bsdf_min = 0; |
100 |
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return; |
101 |
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} |
102 |
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target = cnt/100; /* ignore bottom 1% */ |
103 |
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cnt = 0; |
104 |
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for (i = 0; cnt <= target; i++) |
105 |
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cnt += bsdf_hist[i]; |
106 |
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bsdf_min = histval(i-1); |
107 |
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} |
108 |
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109 |
greg |
2.12 |
/* Determine if the given region is empty of grid samples */ |
110 |
greg |
2.6 |
static int |
111 |
greg |
2.12 |
empty_region(int x0, int x1, int y0, int y1) |
112 |
greg |
2.6 |
{ |
113 |
greg |
2.12 |
int x, y; |
114 |
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115 |
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for (x = x0; x < x1; x++) |
116 |
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for (y = y0; y < y1; y++) |
117 |
greg |
2.20 |
if (dsf_grid[x][y].sum.n) |
118 |
greg |
2.12 |
return(0); |
119 |
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return(1); |
120 |
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} |
121 |
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122 |
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/* Determine if the given region is smooth enough to be a single lobe */ |
123 |
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static int |
124 |
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smooth_region(int x0, int x1, int y0, int y1) |
125 |
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{ |
126 |
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RREAL rMtx[3][3]; |
127 |
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FVECT xvec; |
128 |
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double A, B, C, nvs, sqerr; |
129 |
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int x, y, n; |
130 |
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/* compute planar regression */ |
131 |
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memset(rMtx, 0, sizeof(rMtx)); |
132 |
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memset(xvec, 0, sizeof(xvec)); |
133 |
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for (x = x0; x < x1; x++) |
134 |
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for (y = y0; y < y1; y++) |
135 |
greg |
2.20 |
if ((n = dsf_grid[x][y].sum.n) > 0) { |
136 |
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double z = dsf_grid[x][y].sum.v; |
137 |
greg |
2.13 |
rMtx[0][0] += x*x*(double)n; |
138 |
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rMtx[0][1] += x*y*(double)n; |
139 |
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rMtx[0][2] += x*(double)n; |
140 |
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rMtx[1][1] += y*y*(double)n; |
141 |
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rMtx[1][2] += y*(double)n; |
142 |
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rMtx[2][2] += (double)n; |
143 |
greg |
2.12 |
xvec[0] += x*z; |
144 |
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xvec[1] += y*z; |
145 |
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xvec[2] += z; |
146 |
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} |
147 |
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rMtx[1][0] = rMtx[0][1]; |
148 |
greg |
2.15 |
rMtx[2][0] = rMtx[0][2]; |
149 |
greg |
2.12 |
rMtx[2][1] = rMtx[1][2]; |
150 |
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nvs = rMtx[2][2]; |
151 |
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if (SDinvXform(rMtx, rMtx) != SDEnone) |
152 |
greg |
2.16 |
return(1); /* colinear values */ |
153 |
greg |
2.12 |
A = DOT(rMtx[0], xvec); |
154 |
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B = DOT(rMtx[1], xvec); |
155 |
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C = DOT(rMtx[2], xvec); |
156 |
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sqerr = 0.0; /* compute mean squared error */ |
157 |
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for (x = x0; x < x1; x++) |
158 |
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for (y = y0; y < y1; y++) |
159 |
greg |
2.20 |
if ((n = dsf_grid[x][y].sum.n) > 0) { |
160 |
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double d = A*x + B*y + C - dsf_grid[x][y].sum.v/n; |
161 |
greg |
2.12 |
sqerr += n*d*d; |
162 |
greg |
2.6 |
} |
163 |
greg |
2.12 |
if (sqerr <= nvs*SMOOTH_MSE) /* below absolute MSE threshold? */ |
164 |
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return(1); |
165 |
greg |
2.13 |
/* OR below relative MSE threshold? */ |
166 |
greg |
2.12 |
return(sqerr*nvs <= xvec[2]*xvec[2]*SMOOTH_MSER); |
167 |
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} |
168 |
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169 |
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/* Create new lobe based on integrated samples in region */ |
170 |
greg |
2.21 |
static int |
171 |
greg |
2.12 |
create_lobe(RBFVAL *rvp, int x0, int x1, int y0, int y1) |
172 |
|
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{ |
173 |
|
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double vtot = 0.0; |
174 |
|
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int nv = 0; |
175 |
greg |
2.25 |
double wxsum = 0.0, wysum = 0.0, wtsum = 0.0; |
176 |
greg |
2.12 |
double rad; |
177 |
|
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int x, y; |
178 |
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/* compute average for region */ |
179 |
|
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for (x = x0; x < x1; x++) |
180 |
greg |
2.25 |
for (y = y0; y < y1; y++) |
181 |
|
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if (dsf_grid[x][y].sum.n) { |
182 |
|
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const double v = dsf_grid[x][y].sum.v; |
183 |
|
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const int n = dsf_grid[x][y].sum.n; |
184 |
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|
185 |
|
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if (v > 0) { |
186 |
|
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double wt = v / (double)n; |
187 |
|
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wxsum += wt * x; |
188 |
|
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wysum += wt * y; |
189 |
|
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wtsum += wt; |
190 |
|
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} |
191 |
|
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vtot += v; |
192 |
|
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nv += n; |
193 |
|
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} |
194 |
greg |
2.12 |
if (!nv) { |
195 |
|
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fprintf(stderr, "%s: internal - missing samples in create_lobe\n", |
196 |
|
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progname); |
197 |
|
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exit(1); |
198 |
greg |
2.6 |
} |
199 |
greg |
2.21 |
if (vtot <= 0) /* only create positive lobes */ |
200 |
|
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return(0); |
201 |
greg |
2.12 |
/* peak value based on integral */ |
202 |
|
|
vtot *= (x1-x0)*(y1-y0)*(2.*M_PI/GRIDRES/GRIDRES)/(double)nv; |
203 |
|
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rad = (RSCA/(double)GRIDRES)*(x1-x0); |
204 |
|
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rvp->peak = vtot / ((2.*M_PI) * rad*rad); |
205 |
greg |
2.25 |
rvp->crad = ANG2R(rad); /* put peak at centroid */ |
206 |
|
|
rvp->gx = (int)(wxsum/wtsum + .5); |
207 |
|
|
rvp->gy = (int)(wysum/wtsum + .5); |
208 |
greg |
2.21 |
return(1); |
209 |
greg |
2.6 |
} |
210 |
|
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|
211 |
greg |
2.12 |
/* Recursive function to build radial basis function representation */ |
212 |
greg |
2.6 |
static int |
213 |
greg |
2.12 |
build_rbfrep(RBFVAL **arp, int *np, int x0, int x1, int y0, int y1) |
214 |
greg |
2.6 |
{ |
215 |
greg |
2.12 |
int xmid = (x0+x1)>>1; |
216 |
|
|
int ymid = (y0+y1)>>1; |
217 |
|
|
int branched[4]; |
218 |
|
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int nadded, nleaves; |
219 |
|
|
/* need to make this a leaf? */ |
220 |
|
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if (empty_region(x0, xmid, y0, ymid) || |
221 |
|
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empty_region(xmid, x1, y0, ymid) || |
222 |
|
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empty_region(x0, xmid, ymid, y1) || |
223 |
|
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empty_region(xmid, x1, ymid, y1)) |
224 |
|
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return(0); |
225 |
|
|
/* add children (branches+leaves) */ |
226 |
|
|
if ((branched[0] = build_rbfrep(arp, np, x0, xmid, y0, ymid)) < 0) |
227 |
|
|
return(-1); |
228 |
|
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if ((branched[1] = build_rbfrep(arp, np, xmid, x1, y0, ymid)) < 0) |
229 |
|
|
return(-1); |
230 |
|
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if ((branched[2] = build_rbfrep(arp, np, x0, xmid, ymid, y1)) < 0) |
231 |
|
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return(-1); |
232 |
|
|
if ((branched[3] = build_rbfrep(arp, np, xmid, x1, ymid, y1)) < 0) |
233 |
|
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return(-1); |
234 |
|
|
nadded = branched[0] + branched[1] + branched[2] + branched[3]; |
235 |
|
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nleaves = !branched[0] + !branched[1] + !branched[2] + !branched[3]; |
236 |
|
|
if (!nleaves) /* nothing but branches? */ |
237 |
|
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return(nadded); |
238 |
|
|
/* combine 4 leaves into 1? */ |
239 |
greg |
2.14 |
if ((nleaves == 4) & (x1-x0 <= MAX_RAD) && |
240 |
|
|
smooth_region(x0, x1, y0, y1)) |
241 |
greg |
2.12 |
return(0); |
242 |
|
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/* need more array space? */ |
243 |
|
|
if ((*np+nleaves-1)>>RBFALLOCB != (*np-1)>>RBFALLOCB) { |
244 |
|
|
*arp = (RBFVAL *)realloc(*arp, |
245 |
|
|
sizeof(RBFVAL)*(*np+nleaves-1+(1<<RBFALLOCB))); |
246 |
|
|
if (*arp == NULL) |
247 |
|
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return(-1); |
248 |
greg |
2.6 |
} |
249 |
greg |
2.12 |
/* create lobes for leaves */ |
250 |
greg |
2.21 |
if (!branched[0] && create_lobe(*arp+*np, x0, xmid, y0, ymid)) { |
251 |
|
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++(*np); ++nadded; |
252 |
|
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} |
253 |
|
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if (!branched[1] && create_lobe(*arp+*np, xmid, x1, y0, ymid)) { |
254 |
|
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++(*np); ++nadded; |
255 |
|
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} |
256 |
|
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if (!branched[2] && create_lobe(*arp+*np, x0, xmid, ymid, y1)) { |
257 |
|
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++(*np); ++nadded; |
258 |
|
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} |
259 |
|
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if (!branched[3] && create_lobe(*arp+*np, xmid, x1, ymid, y1)) { |
260 |
|
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++(*np); ++nadded; |
261 |
|
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} |
262 |
greg |
2.12 |
return(nadded); |
263 |
greg |
2.6 |
} |
264 |
|
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|
265 |
greg |
2.1 |
/* Count up filled nodes and build RBF representation from current grid */ |
266 |
|
|
RBFNODE * |
267 |
greg |
2.12 |
make_rbfrep() |
268 |
greg |
2.1 |
{ |
269 |
greg |
2.12 |
RBFNODE *newnode; |
270 |
|
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RBFVAL *rbfarr; |
271 |
greg |
2.1 |
int nn; |
272 |
greg |
2.5 |
/* compute minimum BSDF */ |
273 |
|
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comp_bsdf_min(); |
274 |
greg |
2.12 |
/* create RBF node list */ |
275 |
|
|
rbfarr = NULL; nn = 0; |
276 |
greg |
2.22 |
if (build_rbfrep(&rbfarr, &nn, 0, GRIDRES, 0, GRIDRES) <= 0) { |
277 |
|
|
if (nn) |
278 |
|
|
goto memerr; |
279 |
greg |
2.24 |
fprintf(stderr, |
280 |
|
|
"%s: warning - skipping bad incidence (%.1f,%.1f)\n", |
281 |
|
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progname, theta_in_deg, phi_in_deg); |
282 |
|
|
return(NULL); |
283 |
greg |
2.22 |
} |
284 |
greg |
2.12 |
/* (re)allocate RBF array */ |
285 |
|
|
newnode = (RBFNODE *)realloc(rbfarr, |
286 |
|
|
sizeof(RBFNODE) + sizeof(RBFVAL)*(nn-1)); |
287 |
greg |
2.2 |
if (newnode == NULL) |
288 |
|
|
goto memerr; |
289 |
greg |
2.12 |
/* copy computed lobes into RBF node */ |
290 |
|
|
memmove(newnode->rbfa, newnode, sizeof(RBFVAL)*nn); |
291 |
greg |
2.1 |
newnode->ord = -1; |
292 |
|
|
newnode->next = NULL; |
293 |
|
|
newnode->ejl = NULL; |
294 |
|
|
newnode->invec[2] = sin((M_PI/180.)*theta_in_deg); |
295 |
|
|
newnode->invec[0] = cos((M_PI/180.)*phi_in_deg)*newnode->invec[2]; |
296 |
|
|
newnode->invec[1] = sin((M_PI/180.)*phi_in_deg)*newnode->invec[2]; |
297 |
|
|
newnode->invec[2] = input_orient*sqrt(1. - newnode->invec[2]*newnode->invec[2]); |
298 |
greg |
2.12 |
newnode->vtotal = .0; |
299 |
greg |
2.1 |
newnode->nrbf = nn; |
300 |
greg |
2.12 |
/* compute sum for normalization */ |
301 |
|
|
while (nn-- > 0) |
302 |
|
|
newnode->vtotal += rbf_volume(&newnode->rbfa[nn]); |
303 |
greg |
2.3 |
#ifdef DEBUG |
304 |
greg |
2.12 |
fprintf(stderr, "Built RBF with %d lobes\n", newnode->nrbf); |
305 |
greg |
2.3 |
fprintf(stderr, "Integrated DSF at (%.1f,%.1f) deg. is %.2f\n", |
306 |
|
|
get_theta180(newnode->invec), get_phi360(newnode->invec), |
307 |
|
|
newnode->vtotal); |
308 |
|
|
#endif |
309 |
greg |
2.1 |
insert_dsf(newnode); |
310 |
|
|
return(newnode); |
311 |
greg |
2.2 |
memerr: |
312 |
|
|
fprintf(stderr, "%s: Out of memory in make_rbfrep()\n", progname); |
313 |
|
|
exit(1); |
314 |
greg |
2.1 |
} |