| 1 |
greg |
2.1 |
#ifndef lint |
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greg |
2.6 |
static const char RCSid[] = "$Id: bsdfrbf.c,v 2.5 2013/06/28 23:18:51 greg Exp $"; |
| 3 |
greg |
2.1 |
#endif |
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/* |
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* Radial basis function representation for BSDF data. |
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* |
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* G. Ward |
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*/ |
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#define _USE_MATH_DEFINES |
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#include <stdio.h> |
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#include <stdlib.h> |
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#include <string.h> |
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#include <math.h> |
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#include "bsdfrep.h" |
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#ifndef RSCA |
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#define RSCA 2.7 /* radius scaling factor (empirical) */ |
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#endif |
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/* our loaded grid for this incident angle */ |
| 21 |
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GRIDVAL dsf_grid[GRIDRES][GRIDRES]; |
| 22 |
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| 23 |
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/* Start new DSF input grid */ |
| 24 |
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void |
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new_bsdf_data(double new_theta, double new_phi) |
| 26 |
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{ |
| 27 |
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if (!new_input_direction(new_theta, new_phi)) |
| 28 |
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exit(1); |
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memset(dsf_grid, 0, sizeof(dsf_grid)); |
| 30 |
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} |
| 31 |
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| 32 |
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/* Add BSDF data point */ |
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void |
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add_bsdf_data(double theta_out, double phi_out, double val, int isDSF) |
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{ |
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FVECT ovec; |
| 37 |
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int pos[2]; |
| 38 |
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| 39 |
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if (!output_orient) /* check output orientation */ |
| 40 |
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output_orient = 1 - 2*(theta_out > 90.); |
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else if (output_orient > 0 ^ theta_out < 90.) { |
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fputs("Cannot handle output angles on both sides of surface\n", |
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stderr); |
| 44 |
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exit(1); |
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} |
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ovec[2] = sin((M_PI/180.)*theta_out); |
| 47 |
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ovec[0] = cos((M_PI/180.)*phi_out) * ovec[2]; |
| 48 |
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ovec[1] = sin((M_PI/180.)*phi_out) * ovec[2]; |
| 49 |
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ovec[2] = sqrt(1. - ovec[2]*ovec[2]); |
| 50 |
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| 51 |
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if (!isDSF) |
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val *= ovec[2]; /* convert from BSDF to DSF */ |
| 53 |
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| 54 |
greg |
2.4 |
/* update BSDF histogram */ |
| 55 |
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if (val < BSDF2BIG*ovec[2] && val > BSDF2SML*ovec[2]) |
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++bsdf_hist[histndx(val/ovec[2])]; |
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greg |
2.1 |
pos_from_vec(pos, ovec); |
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dsf_grid[pos[0]][pos[1]].vsum += val; |
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dsf_grid[pos[0]][pos[1]].nval++; |
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} |
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| 64 |
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/* Compute radii for non-empty bins */ |
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/* (distance to furthest empty bin for which non-empty bin is the closest) */ |
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static void |
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compute_radii(void) |
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{ |
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unsigned int fill_grid[GRIDRES][GRIDRES]; |
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unsigned short fill_cnt[GRIDRES][GRIDRES]; |
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FVECT ovec0, ovec1; |
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double ang2, lastang2; |
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int r, i, j, jn, ii, jj, inear, jnear; |
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| 75 |
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r = GRIDRES/2; /* proceed in zig-zag */ |
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for (i = 0; i < GRIDRES; i++) |
| 77 |
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for (jn = 0; jn < GRIDRES; jn++) { |
| 78 |
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j = (i&1) ? jn : GRIDRES-1-jn; |
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if (dsf_grid[i][j].nval) /* find empty grid pos. */ |
| 80 |
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continue; |
| 81 |
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ovec_from_pos(ovec0, i, j); |
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inear = jnear = -1; /* find nearest non-empty */ |
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lastang2 = M_PI*M_PI; |
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for (ii = i-r; ii <= i+r; ii++) { |
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if (ii < 0) continue; |
| 86 |
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if (ii >= GRIDRES) break; |
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for (jj = j-r; jj <= j+r; jj++) { |
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if (jj < 0) continue; |
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if (jj >= GRIDRES) break; |
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if (!dsf_grid[ii][jj].nval) |
| 91 |
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continue; |
| 92 |
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ovec_from_pos(ovec1, ii, jj); |
| 93 |
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ang2 = 2. - 2.*DOT(ovec0,ovec1); |
| 94 |
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if (ang2 >= lastang2) |
| 95 |
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continue; |
| 96 |
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lastang2 = ang2; |
| 97 |
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inear = ii; jnear = jj; |
| 98 |
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} |
| 99 |
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} |
| 100 |
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if (inear < 0) { |
| 101 |
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fprintf(stderr, |
| 102 |
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"%s: Could not find non-empty neighbor!\n", |
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progname); |
| 104 |
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exit(1); |
| 105 |
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} |
| 106 |
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ang2 = sqrt(lastang2); |
| 107 |
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r = ANG2R(ang2); /* record if > previous */ |
| 108 |
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if (r > dsf_grid[inear][jnear].crad) |
| 109 |
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dsf_grid[inear][jnear].crad = r; |
| 110 |
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/* next search radius */ |
| 111 |
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r = ang2*(2.*GRIDRES/M_PI) + 3; |
| 112 |
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} |
| 113 |
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/* blur radii over hemisphere */ |
| 114 |
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memset(fill_grid, 0, sizeof(fill_grid)); |
| 115 |
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memset(fill_cnt, 0, sizeof(fill_cnt)); |
| 116 |
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for (i = 0; i < GRIDRES; i++) |
| 117 |
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for (j = 0; j < GRIDRES; j++) { |
| 118 |
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if (!dsf_grid[i][j].crad) |
| 119 |
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continue; /* missing distance */ |
| 120 |
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r = R2ANG(dsf_grid[i][j].crad)*(2.*RSCA*GRIDRES/M_PI); |
| 121 |
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for (ii = i-r; ii <= i+r; ii++) { |
| 122 |
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if (ii < 0) continue; |
| 123 |
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if (ii >= GRIDRES) break; |
| 124 |
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for (jj = j-r; jj <= j+r; jj++) { |
| 125 |
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if (jj < 0) continue; |
| 126 |
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if (jj >= GRIDRES) break; |
| 127 |
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if ((ii-i)*(ii-i) + (jj-j)*(jj-j) > r*r) |
| 128 |
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continue; |
| 129 |
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fill_grid[ii][jj] += dsf_grid[i][j].crad; |
| 130 |
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fill_cnt[ii][jj]++; |
| 131 |
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} |
| 132 |
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} |
| 133 |
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} |
| 134 |
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/* copy back blurred radii */ |
| 135 |
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for (i = 0; i < GRIDRES; i++) |
| 136 |
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for (j = 0; j < GRIDRES; j++) |
| 137 |
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if (fill_cnt[i][j]) |
| 138 |
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dsf_grid[i][j].crad = fill_grid[i][j]/fill_cnt[i][j]; |
| 139 |
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} |
| 140 |
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| 141 |
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/* Cull points for more uniform distribution, leave all nval 0 or 1 */ |
| 142 |
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static void |
| 143 |
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cull_values(void) |
| 144 |
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{ |
| 145 |
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FVECT ovec0, ovec1; |
| 146 |
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double maxang, maxang2; |
| 147 |
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int i, j, ii, jj, r; |
| 148 |
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/* simple greedy algorithm */ |
| 149 |
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for (i = 0; i < GRIDRES; i++) |
| 150 |
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for (j = 0; j < GRIDRES; j++) { |
| 151 |
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if (!dsf_grid[i][j].nval) |
| 152 |
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continue; |
| 153 |
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if (!dsf_grid[i][j].crad) |
| 154 |
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continue; /* shouldn't happen */ |
| 155 |
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ovec_from_pos(ovec0, i, j); |
| 156 |
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maxang = 2.*R2ANG(dsf_grid[i][j].crad); |
| 157 |
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if (maxang > ovec0[2]) /* clamp near horizon */ |
| 158 |
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maxang = ovec0[2]; |
| 159 |
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r = maxang*(2.*GRIDRES/M_PI) + 1; |
| 160 |
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maxang2 = maxang*maxang; |
| 161 |
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for (ii = i-r; ii <= i+r; ii++) { |
| 162 |
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if (ii < 0) continue; |
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if (ii >= GRIDRES) break; |
| 164 |
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for (jj = j-r; jj <= j+r; jj++) { |
| 165 |
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if (jj < 0) continue; |
| 166 |
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if (jj >= GRIDRES) break; |
| 167 |
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if (!dsf_grid[ii][jj].nval) |
| 168 |
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continue; |
| 169 |
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if ((ii == i) & (jj == j)) |
| 170 |
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continue; /* don't get self-absorbed */ |
| 171 |
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ovec_from_pos(ovec1, ii, jj); |
| 172 |
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if (2. - 2.*DOT(ovec0,ovec1) >= maxang2) |
| 173 |
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continue; |
| 174 |
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/* absorb sum */ |
| 175 |
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dsf_grid[i][j].vsum += dsf_grid[ii][jj].vsum; |
| 176 |
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dsf_grid[i][j].nval += dsf_grid[ii][jj].nval; |
| 177 |
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/* keep value, though */ |
| 178 |
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dsf_grid[ii][jj].vsum /= (float)dsf_grid[ii][jj].nval; |
| 179 |
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dsf_grid[ii][jj].nval = 0; |
| 180 |
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} |
| 181 |
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} |
| 182 |
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} |
| 183 |
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/* final averaging pass */ |
| 184 |
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for (i = 0; i < GRIDRES; i++) |
| 185 |
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for (j = 0; j < GRIDRES; j++) |
| 186 |
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if (dsf_grid[i][j].nval > 1) { |
| 187 |
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dsf_grid[i][j].vsum /= (float)dsf_grid[i][j].nval; |
| 188 |
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dsf_grid[i][j].nval = 1; |
| 189 |
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} |
| 190 |
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} |
| 191 |
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| 192 |
greg |
2.5 |
/* Compute minimum BSDF from histogram and clear it */ |
| 193 |
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static void |
| 194 |
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comp_bsdf_min() |
| 195 |
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{ |
| 196 |
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int cnt; |
| 197 |
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int i, target; |
| 198 |
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| 199 |
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cnt = 0; |
| 200 |
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for (i = HISTLEN; i--; ) |
| 201 |
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cnt += bsdf_hist[i]; |
| 202 |
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if (!cnt) { /* shouldn't happen */ |
| 203 |
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bsdf_min = 0; |
| 204 |
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return; |
| 205 |
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} |
| 206 |
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target = cnt/100; /* ignore bottom 1% */ |
| 207 |
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cnt = 0; |
| 208 |
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for (i = 0; cnt <= target; i++) |
| 209 |
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cnt += bsdf_hist[i]; |
| 210 |
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bsdf_min = histval(i-1); |
| 211 |
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memset(bsdf_hist, 0, sizeof(bsdf_hist)); |
| 212 |
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} |
| 213 |
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| 214 |
greg |
2.6 |
/* Find n nearest sub-sampled neighbors to the given grid position */ |
| 215 |
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static int |
| 216 |
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get_neighbors(int neigh[][2], int n, const int i, const int j) |
| 217 |
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{ |
| 218 |
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int k = 0; |
| 219 |
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int r; |
| 220 |
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/* search concentric squares */ |
| 221 |
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for (r = 1; r < GRIDRES; r++) { |
| 222 |
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int ii, jj; |
| 223 |
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for (ii = i-r; ii <= i+r; ii++) { |
| 224 |
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int jstep = 1; |
| 225 |
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if (ii < 0) continue; |
| 226 |
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if (ii >= GRIDRES) break; |
| 227 |
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if ((i-r < ii) & (ii < i+r)) |
| 228 |
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jstep = r<<1; |
| 229 |
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for (jj = j-r; jj <= j+r; jj += jstep) { |
| 230 |
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if (jj < 0) continue; |
| 231 |
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if (jj >= GRIDRES) break; |
| 232 |
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if (dsf_grid[ii][jj].nval) { |
| 233 |
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neigh[k][0] = ii; |
| 234 |
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neigh[k][1] = jj; |
| 235 |
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if (++k >= n) |
| 236 |
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return(n); |
| 237 |
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} |
| 238 |
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} |
| 239 |
|
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} |
| 240 |
|
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} |
| 241 |
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return(k); |
| 242 |
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} |
| 243 |
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| 244 |
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/* Adjust coded radius for the given grid position based on neighborhood */ |
| 245 |
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static int |
| 246 |
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adj_coded_radius(const int i, const int j) |
| 247 |
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{ |
| 248 |
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const double max_frac = 0.33; |
| 249 |
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const double rad0 = R2ANG(dsf_grid[i][j].crad); |
| 250 |
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double currad = RSCA * rad0; |
| 251 |
|
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int neigh[5][2]; |
| 252 |
|
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int n; |
| 253 |
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FVECT our_dir; |
| 254 |
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| 255 |
|
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ovec_from_pos(our_dir, i, j); |
| 256 |
|
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n = get_neighbors(neigh, 5, i, j); |
| 257 |
|
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while (n--) { |
| 258 |
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FVECT their_dir; |
| 259 |
|
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double max_ratio, rad_ok2; |
| 260 |
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/* check our value at neighbor */ |
| 261 |
|
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ovec_from_pos(their_dir, neigh[n][0], neigh[n][1]); |
| 262 |
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max_ratio = max_frac * dsf_grid[neigh[n][0]][neigh[n][1]].vsum |
| 263 |
|
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/ dsf_grid[i][j].vsum; |
| 264 |
|
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if (max_ratio >= 1) |
| 265 |
|
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continue; |
| 266 |
|
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rad_ok2 = (DOT(their_dir,our_dir) - 1.)/log(max_ratio); |
| 267 |
|
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if (rad_ok2 >= currad*currad) |
| 268 |
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continue; /* value fraction OK */ |
| 269 |
|
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currad = sqrt(rad_ok2); /* else reduce lobe radius */ |
| 270 |
|
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if (currad <= rad0) /* limit how small we'll go */ |
| 271 |
|
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return(dsf_grid[i][j].crad); |
| 272 |
|
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} |
| 273 |
|
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return(ANG2R(currad)); /* encode selected radius */ |
| 274 |
|
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} |
| 275 |
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| 276 |
greg |
2.1 |
/* Count up filled nodes and build RBF representation from current grid */ |
| 277 |
|
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RBFNODE * |
| 278 |
|
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make_rbfrep(void) |
| 279 |
|
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{ |
| 280 |
|
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int niter = 16; |
| 281 |
|
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double lastVar, thisVar = 100.; |
| 282 |
|
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int nn; |
| 283 |
|
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RBFNODE *newnode; |
| 284 |
greg |
2.2 |
RBFVAL *itera; |
| 285 |
greg |
2.1 |
int i, j; |
| 286 |
|
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/* compute RBF radii */ |
| 287 |
|
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compute_radii(); |
| 288 |
|
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/* coagulate lobes */ |
| 289 |
|
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cull_values(); |
| 290 |
|
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nn = 0; /* count selected bins */ |
| 291 |
|
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for (i = 0; i < GRIDRES; i++) |
| 292 |
|
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for (j = 0; j < GRIDRES; j++) |
| 293 |
|
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nn += dsf_grid[i][j].nval; |
| 294 |
greg |
2.5 |
/* compute minimum BSDF */ |
| 295 |
|
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comp_bsdf_min(); |
| 296 |
greg |
2.1 |
/* allocate RBF array */ |
| 297 |
|
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newnode = (RBFNODE *)malloc(sizeof(RBFNODE) + sizeof(RBFVAL)*(nn-1)); |
| 298 |
greg |
2.2 |
if (newnode == NULL) |
| 299 |
|
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goto memerr; |
| 300 |
greg |
2.1 |
newnode->ord = -1; |
| 301 |
|
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newnode->next = NULL; |
| 302 |
|
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newnode->ejl = NULL; |
| 303 |
|
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newnode->invec[2] = sin((M_PI/180.)*theta_in_deg); |
| 304 |
|
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newnode->invec[0] = cos((M_PI/180.)*phi_in_deg)*newnode->invec[2]; |
| 305 |
|
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newnode->invec[1] = sin((M_PI/180.)*phi_in_deg)*newnode->invec[2]; |
| 306 |
|
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newnode->invec[2] = input_orient*sqrt(1. - newnode->invec[2]*newnode->invec[2]); |
| 307 |
|
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newnode->vtotal = 0; |
| 308 |
|
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newnode->nrbf = nn; |
| 309 |
|
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nn = 0; /* fill RBF array */ |
| 310 |
|
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for (i = 0; i < GRIDRES; i++) |
| 311 |
|
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for (j = 0; j < GRIDRES; j++) |
| 312 |
|
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if (dsf_grid[i][j].nval) { |
| 313 |
|
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newnode->rbfa[nn].peak = dsf_grid[i][j].vsum; |
| 314 |
greg |
2.6 |
newnode->rbfa[nn].crad = adj_coded_radius(i, j); |
| 315 |
greg |
2.1 |
newnode->rbfa[nn].gx = i; |
| 316 |
|
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newnode->rbfa[nn].gy = j; |
| 317 |
|
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++nn; |
| 318 |
|
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} |
| 319 |
|
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/* iterate to improve interpolation accuracy */ |
| 320 |
greg |
2.2 |
itera = (RBFVAL *)malloc(sizeof(RBFVAL)*newnode->nrbf); |
| 321 |
|
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if (itera == NULL) |
| 322 |
|
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goto memerr; |
| 323 |
|
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memcpy(itera, newnode->rbfa, sizeof(RBFVAL)*newnode->nrbf); |
| 324 |
greg |
2.1 |
do { |
| 325 |
|
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double dsum = 0, dsum2 = 0; |
| 326 |
|
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nn = 0; |
| 327 |
|
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for (i = 0; i < GRIDRES; i++) |
| 328 |
|
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for (j = 0; j < GRIDRES; j++) |
| 329 |
|
|
if (dsf_grid[i][j].nval) { |
| 330 |
|
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FVECT odir; |
| 331 |
|
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double corr; |
| 332 |
|
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ovec_from_pos(odir, i, j); |
| 333 |
greg |
2.2 |
itera[nn++].peak *= corr = |
| 334 |
greg |
2.1 |
dsf_grid[i][j].vsum / |
| 335 |
|
|
eval_rbfrep(newnode, odir); |
| 336 |
greg |
2.2 |
dsum += 1. - corr; |
| 337 |
|
|
dsum2 += (1.-corr)*(1.-corr); |
| 338 |
greg |
2.1 |
} |
| 339 |
greg |
2.2 |
memcpy(newnode->rbfa, itera, sizeof(RBFVAL)*newnode->nrbf); |
| 340 |
greg |
2.1 |
lastVar = thisVar; |
| 341 |
|
|
thisVar = dsum2/(double)nn; |
| 342 |
|
|
#ifdef DEBUG |
| 343 |
|
|
fprintf(stderr, "Avg., RMS error: %.1f%% %.1f%%\n", |
| 344 |
|
|
100.*dsum/(double)nn, |
| 345 |
|
|
100.*sqrt(thisVar)); |
| 346 |
|
|
#endif |
| 347 |
|
|
} while (--niter > 0 && lastVar-thisVar > 0.02*lastVar); |
| 348 |
|
|
|
| 349 |
greg |
2.2 |
free(itera); |
| 350 |
greg |
2.1 |
nn = 0; /* compute sum for normalization */ |
| 351 |
|
|
while (nn < newnode->nrbf) |
| 352 |
|
|
newnode->vtotal += rbf_volume(&newnode->rbfa[nn++]); |
| 353 |
greg |
2.3 |
#ifdef DEBUG |
| 354 |
|
|
fprintf(stderr, "Integrated DSF at (%.1f,%.1f) deg. is %.2f\n", |
| 355 |
|
|
get_theta180(newnode->invec), get_phi360(newnode->invec), |
| 356 |
|
|
newnode->vtotal); |
| 357 |
|
|
#endif |
| 358 |
greg |
2.1 |
insert_dsf(newnode); |
| 359 |
|
|
|
| 360 |
|
|
return(newnode); |
| 361 |
greg |
2.2 |
memerr: |
| 362 |
|
|
fprintf(stderr, "%s: Out of memory in make_rbfrep()\n", progname); |
| 363 |
|
|
exit(1); |
| 364 |
greg |
2.1 |
} |
