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#ifndef lint |
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static const char RCSid[] = "$Id$"; |
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#endif |
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/* |
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* gendaymtx.c |
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* |
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* Generate a daylight matrix based on Perez Sky Model. |
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* |
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* Most of this code is borrowed (see copyright below) from Ian Ashdown's |
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* excellent re-implementation of Jean-Jacques Delaunay's gendaylit.c |
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* |
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* Created by Greg Ward on 1/16/13. |
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*/ |
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|
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/********************************************************************* |
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* |
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* H32_gendaylit.CPP - Perez Sky Model Calculation |
18 |
* |
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* Version: 1.00A |
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* |
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* History: 09/10/01 - Created. |
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* 11/10/08 - Modified for Unix compilation. |
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* 11/10/12 - Fixed conditional __max directive. |
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* 1/11/13 - Tweaks and optimizations (G.Ward) |
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* |
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* Compilers: Microsoft Visual C/C++ Professional V10.0 |
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* |
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* Author: Ian Ashdown, P.Eng. |
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* byHeart Consultants Limited |
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* 620 Ballantree Road |
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* West Vancouver, B.C. |
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* Canada V7S 1W3 |
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* e-mail: [email protected] |
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* |
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* References: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. |
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* Stewart. 1990. ìModeling Daylight Availability and |
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* Irradiance Components from Direct and Global |
38 |
* Irradiance,î Solar Energy 44(5):271-289. |
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* |
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* Perez, R., R. Seals, and J. Michalsky. 1993. |
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* ìAll-Weather Model for Sky Luminance Distribution - |
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* Preliminary Configuration and Validation,î Solar Energy |
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* 50(3):235-245. |
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* |
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* Perez, R., R. Seals, and J. Michalsky. 1993. "ERRATUM to |
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* All-Weather Model for Sky Luminance Distribution - |
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* Preliminary Configuration and Validation,î Solar Energy |
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* 51(5):423. |
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* |
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* NOTE: This program is a completely rewritten version of |
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* gendaylit.c written by Jean-Jacques Delaunay (1994). |
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* |
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* Copyright 2009-2012 byHeart Consultants Limited. All rights |
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* reserved. |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted for personal and commercial purposes |
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* provided that redistribution of source code must retain the above |
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* copyright notice, this list of conditions and the following |
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* disclaimer: |
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* |
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* THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESSED OR IMPLIED |
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
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* DISCLAIMED. IN NO EVENT SHALL byHeart Consultants Limited OR |
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* ITS EMPLOYEES BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF |
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* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED |
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN |
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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* POSSIBILITY OF SUCH DAMAGE. |
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* |
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*********************************************************************/ |
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|
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/* Zenith is along the Z-axis */ |
78 |
/* X-axis points east */ |
79 |
/* Y-axis points north */ |
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/* azimuth is measured as degrees or radians east of North */ |
81 |
|
82 |
/* Include files */ |
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#define _USE_MATH_DEFINES |
84 |
#include <stdio.h> |
85 |
#include <stdlib.h> |
86 |
#include <string.h> |
87 |
#include <ctype.h> |
88 |
#include "rtmath.h" |
89 |
#include "color.h" |
90 |
|
91 |
char *progname; /* Program name */ |
92 |
char errmsg[128]; /* Error message buffer */ |
93 |
const double DC_SolarConstantE = 1367.0; /* Solar constant W/m^2 */ |
94 |
const double DC_SolarConstantL = 127.5; /* Solar constant klux */ |
95 |
|
96 |
double altitude; /* Solar altitude (radians) */ |
97 |
double azimuth; /* Solar azimuth (radians) */ |
98 |
double apwc; /* Atmospheric precipitable water content */ |
99 |
double dew_point = 11.0; /* Surface dew point temperature (deg. C) */ |
100 |
double diff_illum; /* Diffuse illuminance */ |
101 |
double diff_irrad; /* Diffuse irradiance */ |
102 |
double dir_illum; /* Direct illuminance */ |
103 |
double dir_irrad; /* Direct irradiance */ |
104 |
int julian_date; /* Julian date */ |
105 |
double perez_param[5]; /* Perez sky model parameters */ |
106 |
double sky_brightness; /* Sky brightness */ |
107 |
double sky_clearness; /* Sky clearness */ |
108 |
double solar_rad; /* Solar radiance */ |
109 |
double sun_zenith; /* Sun zenith angle (radians) */ |
110 |
int input = 0; /* Input type */ |
111 |
|
112 |
extern double dmax( double, double ); |
113 |
extern double CalcAirMass(); |
114 |
extern double CalcDiffuseIllumRatio( int ); |
115 |
extern double CalcDiffuseIrradiance(); |
116 |
extern double CalcDirectIllumRatio( int ); |
117 |
extern double CalcDirectIrradiance(); |
118 |
extern double CalcEccentricity(); |
119 |
extern double CalcPrecipWater( double ); |
120 |
extern double CalcRelHorzIllum( float *parr ); |
121 |
extern double CalcRelLuminance( double, double ); |
122 |
extern double CalcSkyBrightness(); |
123 |
extern double CalcSkyClearness(); |
124 |
extern int CalcSkyParamFromIllum(); |
125 |
extern int GetCategoryIndex(); |
126 |
extern void CalcPerezParam( double, double, double, int ); |
127 |
extern void CalcSkyPatchLumin( float *parr ); |
128 |
extern void ComputeSky( float *parr ); |
129 |
|
130 |
/* Degrees into radians */ |
131 |
#define DegToRad(deg) ((deg)*(PI/180.)) |
132 |
|
133 |
/* Radiuans into degrees */ |
134 |
#define RadToDeg(rad) ((rad)*(180./PI)) |
135 |
|
136 |
|
137 |
/* Perez sky model coefficients */ |
138 |
|
139 |
/* Reference: Perez, R., R. Seals, and J. Michalsky, 1993. "All- */ |
140 |
/* Weather Model for Sky Luminance Distribution - */ |
141 |
/* Preliminary Configuration and Validation," Solar */ |
142 |
/* Energy 50(3):235-245, Table 1. */ |
143 |
|
144 |
static const double PerezCoeff[8][20] = |
145 |
{ |
146 |
/* Sky clearness (epsilon): 1.000 to 1.065 */ |
147 |
{ 1.3525, -0.2576, -0.2690, -1.4366, -0.7670, |
148 |
0.0007, 1.2734, -0.1233, 2.8000, 0.6004, |
149 |
1.2375, 1.0000, 1.8734, 0.6297, 0.9738, |
150 |
0.2809, 0.0356, -0.1246, -0.5718, 0.9938 }, |
151 |
/* Sky clearness (epsilon): 1.065 to 1.230 */ |
152 |
{ -1.2219, -0.7730, 1.4148, 1.1016, -0.2054, |
153 |
0.0367, -3.9128, 0.9156, 6.9750, 0.1774, |
154 |
6.4477, -0.1239, -1.5798, -0.5081, -1.7812, |
155 |
0.1080, 0.2624, 0.0672, -0.2190, -0.4285 }, |
156 |
/* Sky clearness (epsilon): 1.230 to 1.500 */ |
157 |
{ -1.1000, -0.2515, 0.8952, 0.0156, 0.2782, |
158 |
-0.1812, - 4.5000, 1.1766, 24.7219, -13.0812, |
159 |
-37.7000, 34.8438, -5.0000, 1.5218, 3.9229, |
160 |
-2.6204, -0.0156, 0.1597, 0.4199, -0.5562 }, |
161 |
/* Sky clearness (epsilon): 1.500 to 1.950 */ |
162 |
{ -0.5484, -0.6654, -0.2672, 0.7117, 0.7234, |
163 |
-0.6219, -5.6812, 2.6297, 33.3389, -18.3000, |
164 |
-62.2500, 52.0781, -3.5000, 0.0016, 1.1477, |
165 |
0.1062, 0.4659, -0.3296, -0.0876, -0.0329 }, |
166 |
/* Sky clearness (epsilon): 1.950 to 2.800 */ |
167 |
{ -0.6000, -0.3566, -2.5000, 2.3250, 0.2937, |
168 |
0.0496, -5.6812, 1.8415, 21.0000, -4.7656 , |
169 |
-21.5906, 7.2492, -3.5000, -0.1554, 1.4062, |
170 |
0.3988, 0.0032, 0.0766, -0.0656, -0.1294 }, |
171 |
/* Sky clearness (epsilon): 2.800 to 4.500 */ |
172 |
{ -1.0156, -0.3670, 1.0078, 1.4051, 0.2875, |
173 |
-0.5328, -3.8500, 3.3750, 14.0000, -0.9999, |
174 |
-7.1406, 7.5469, -3.4000, -0.1078, -1.0750, |
175 |
1.5702, -0.0672, 0.4016, 0.3017, -0.4844 }, |
176 |
/* Sky clearness (epsilon): 4.500 to 6.200 */ |
177 |
{ -1.0000, 0.0211, 0.5025, -0.5119, -0.3000, |
178 |
0.1922, 0.7023, -1.6317, 19.0000, -5.0000, |
179 |
1.2438, -1.9094, -4.0000, 0.0250, 0.3844, |
180 |
0.2656, 1.0468, -0.3788, -2.4517, 1.4656 }, |
181 |
/* Sky clearness (epsilon): 6.200 to ... */ |
182 |
{ -1.0500, 0.0289, 0.4260, 0.3590, -0.3250, |
183 |
0.1156, 0.7781, 0.0025, 31.0625, -14.5000, |
184 |
-46.1148, 55.3750, -7.2312, 0.4050, 13.3500, |
185 |
0.6234, 1.5000, -0.6426, 1.8564, 0.5636 } |
186 |
}; |
187 |
|
188 |
/* Perez irradiance component model coefficients */ |
189 |
|
190 |
/* Reference: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. */ |
191 |
/* Stewart. 1990. ìModeling Daylight Availability and */ |
192 |
/* Irradiance Components from Direct and Global */ |
193 |
/* Irradiance,î Solar Energy 44(5):271-289. */ |
194 |
|
195 |
typedef struct |
196 |
{ |
197 |
double lower; /* Lower bound */ |
198 |
double upper; /* Upper bound */ |
199 |
} CategoryBounds; |
200 |
|
201 |
/* Perez sky clearness (epsilon) categories (Table 1) */ |
202 |
static const CategoryBounds SkyClearCat[8] = |
203 |
{ |
204 |
{ 1.000, 1.065 }, /* Overcast */ |
205 |
{ 1.065, 1.230 }, |
206 |
{ 1.230, 1.500 }, |
207 |
{ 1.500, 1.950 }, |
208 |
{ 1.950, 2.800 }, |
209 |
{ 2.800, 4.500 }, |
210 |
{ 4.500, 6.200 }, |
211 |
{ 6.200, 12.00 } /* Clear */ |
212 |
}; |
213 |
|
214 |
/* Luminous efficacy model coefficients */ |
215 |
typedef struct |
216 |
{ |
217 |
double a; |
218 |
double b; |
219 |
double c; |
220 |
double d; |
221 |
} ModelCoeff; |
222 |
|
223 |
/* Diffuse luminous efficacy model coefficients (Table 4, Eqn. 7) */ |
224 |
static const ModelCoeff DiffuseLumEff[8] = |
225 |
{ |
226 |
{ 97.24, -0.46, 12.00, -8.91 }, |
227 |
{ 107.22, 1.15, 0.59, -3.95 }, |
228 |
{ 104.97, 2.96, -5.53, -8.77 }, |
229 |
{ 102.39, 5.59, -13.95, -13.90 }, |
230 |
{ 100.71, 5.94, -22.75, -23.74 }, |
231 |
{ 106.42, 3.83, -36.15, -28.83 }, |
232 |
{ 141.88, 1.90, -53.24, -14.03 }, |
233 |
{ 152.23, 0.35, -45.27, -7.98 } |
234 |
}; |
235 |
|
236 |
/* Direct luminous efficacy model coefficients (Table 4, Eqn. 8) */ |
237 |
static const ModelCoeff DirectLumEff[8] = |
238 |
{ |
239 |
{ 57.20, -4.55, -2.98, 117.12 }, |
240 |
{ 98.99, -3.46, -1.21, 12.38 }, |
241 |
{ 109.83, -4.90, -1.71, -8.81 }, |
242 |
{ 110.34, -5.84, -1.99, -4.56 }, |
243 |
{ 106.36, -3.97, -1.75, -6.16 }, |
244 |
{ 107.19, -1.25, -1.51, -26.73 }, |
245 |
{ 105.75, 0.77, -1.26, -34.44 }, |
246 |
{ 101.18, 1.58, -1.10, -8.29 } |
247 |
}; |
248 |
|
249 |
extern int jdate(int month, int day); |
250 |
extern double stadj(int jd); |
251 |
extern double sdec(int jd); |
252 |
extern double salt(double sd, double st); |
253 |
extern double sazi(double sd, double st); |
254 |
/* sun calculation constants */ |
255 |
extern double s_latitude; |
256 |
extern double s_longitude; |
257 |
extern double s_meridian; |
258 |
|
259 |
double grefl = 0.2; /* diffuse ground reflectance */ |
260 |
|
261 |
int verbose = 0; /* progress reports to stderr? */ |
262 |
|
263 |
int outfmt = 'a'; /* output format */ |
264 |
|
265 |
int rhsubdiv = 1; /* Reinhart sky subdivisions */ |
266 |
|
267 |
float skycolor[3] = {.96, 1.004, 1.118}; /* sky coloration */ |
268 |
|
269 |
int do_sun = 1; /* output direct solar contribution? */ |
270 |
|
271 |
int nskypatch; /* number of Reinhart patches */ |
272 |
float *rh_palt; /* sky patch altitudes (radians) */ |
273 |
float *rh_pazi; /* sky patch azimuths (radians) */ |
274 |
float *rh_dom; /* sky patch solid angle (sr) */ |
275 |
|
276 |
#define vector(v,alt,azi) ( (v)[1] = tcos(alt), \ |
277 |
(v)[0] = (v)[1]*tsin(azi), \ |
278 |
(v)[1] *= tcos(azi), \ |
279 |
(v)[2] = tsin(alt) ) |
280 |
|
281 |
#define rh_vector(v,i) vector(v,rh_palt[i],rh_pazi[i]) |
282 |
|
283 |
#define rh_cos(i) tsin(rh_palt[i]) |
284 |
|
285 |
extern int rh_init(void); |
286 |
extern float * resize_dmatrix(float *mtx_data, int nsteps, int npatch); |
287 |
extern void AddDirect(float *parr); |
288 |
|
289 |
int |
290 |
main(int argc, char *argv[]) |
291 |
{ |
292 |
char buf[256]; |
293 |
double elevation; /* site elevation (meters) */ |
294 |
int dir_is_horiz; /* direct is meas. on horizontal? */ |
295 |
float *mtx_data = NULL; /* our matrix data */ |
296 |
int ntsteps = 0; /* number of rows in matrix */ |
297 |
int last_monthly = 0; /* month of last report */ |
298 |
int mo, da; /* month (1-12) and day (1-31) */ |
299 |
double hr; /* hour (local standard time) */ |
300 |
double dir, dif; /* direct and diffuse values */ |
301 |
int mtx_offset; |
302 |
int i, j; |
303 |
|
304 |
progname = argv[0]; |
305 |
/* get options */ |
306 |
for (i = 1; i < argc && argv[i][0] == '-'; i++) |
307 |
switch (argv[i][1]) { |
308 |
case 'g': |
309 |
grefl = atof(argv[++i]); |
310 |
break; |
311 |
case 'v': |
312 |
verbose++; |
313 |
break; |
314 |
case 'o': |
315 |
switch (argv[i][2]) { |
316 |
case 'f': |
317 |
case 'd': |
318 |
case 'a': |
319 |
outfmt = argv[i][2]; |
320 |
break; |
321 |
default: |
322 |
goto userr; |
323 |
} |
324 |
break; |
325 |
case 'm': |
326 |
rhsubdiv = atoi(argv[++i]); |
327 |
break; |
328 |
case 'c': |
329 |
skycolor[0] = atof(argv[++i]); |
330 |
skycolor[1] = atof(argv[++i]); |
331 |
skycolor[2] = atof(argv[++i]); |
332 |
break; |
333 |
case 'd': |
334 |
do_sun = 1; |
335 |
skycolor[0] = skycolor[1] = skycolor[2] = 0; |
336 |
break; |
337 |
case 's': |
338 |
do_sun = 0; |
339 |
if (skycolor[1] <= 1e-4) |
340 |
skycolor[0] = skycolor[1] = skycolor[2] = 1; |
341 |
break; |
342 |
default: |
343 |
goto userr; |
344 |
} |
345 |
if (i < argc-1) |
346 |
goto userr; |
347 |
if (i == argc-1 && freopen(argv[i], "r", stdin) == NULL) { |
348 |
fprintf(stderr, "%s: cannot open '%s' for input\n", |
349 |
progname, argv[i]); |
350 |
exit(1); |
351 |
} |
352 |
if (verbose) { |
353 |
if (i == argc-1) |
354 |
fprintf(stderr, "%s: reading weather tape '%s'\n", |
355 |
progname, argv[i]); |
356 |
else |
357 |
fprintf(stderr, "%s: reading weather tape from <stdin>\n", |
358 |
progname); |
359 |
} |
360 |
/* read weather tape header */ |
361 |
if (scanf("place %[^\n]\n", buf) != 1) |
362 |
goto fmterr; |
363 |
if (scanf("latitude %lf\n", &s_latitude) != 1) |
364 |
goto fmterr; |
365 |
if (scanf("longitude %lf\n", &s_longitude) != 1) |
366 |
goto fmterr; |
367 |
if (scanf("time_zone %lf\n", &s_meridian) != 1) |
368 |
goto fmterr; |
369 |
if (scanf("site_elevation %lf\n", &elevation) != 1) |
370 |
goto fmterr; |
371 |
if (scanf("weather_data_file_units %d\n", &input) != 1) |
372 |
goto fmterr; |
373 |
switch (input) { /* translate units */ |
374 |
case 1: |
375 |
input = 1; /* radiometric quantities */ |
376 |
dir_is_horiz = 0; /* direct is perpendicular meas. */ |
377 |
break; |
378 |
case 2: |
379 |
input = 1; /* radiometric quantities */ |
380 |
dir_is_horiz = 1; /* solar measured horizontally */ |
381 |
break; |
382 |
case 3: |
383 |
input = 2; /* photometric quantities */ |
384 |
dir_is_horiz = 0; /* direct is perpendicular meas. */ |
385 |
break; |
386 |
default: |
387 |
goto fmterr; |
388 |
} |
389 |
rh_init(); /* initialize sky patches */ |
390 |
if (verbose) { |
391 |
fprintf(stderr, "%s: location '%s'\n", progname, buf); |
392 |
fprintf(stderr, "%s: (lat,long)=(%.1f,%.1f) degrees north, west\n", |
393 |
progname, s_latitude, s_longitude); |
394 |
fprintf(stderr, "%s: %d sky patches per time step\n", |
395 |
progname, nskypatch); |
396 |
} |
397 |
/* process each time step in tape */ |
398 |
while (scanf("%d %d %lf %lf %lf\n", &mo, &da, &hr, &dir, &dif) == 5) { |
399 |
double sda, sta; |
400 |
/* make space for next time step */ |
401 |
mtx_offset = 3*nskypatch*ntsteps++; |
402 |
mtx_data = resize_dmatrix(mtx_data, ntsteps, nskypatch); |
403 |
if (dif <= 1e-4) { |
404 |
memset(mtx_data+mtx_offset, 0, sizeof(float)*3*nskypatch); |
405 |
continue; |
406 |
} |
407 |
if (verbose && mo != last_monthly) |
408 |
fprintf(stderr, "%s: stepping through month %d...\n", |
409 |
progname, last_monthly=mo); |
410 |
/* compute solar position */ |
411 |
julian_date = jdate(mo, da); |
412 |
sda = sdec(julian_date); |
413 |
sta = stadj(julian_date); |
414 |
altitude = salt(sda, hr+sta); |
415 |
azimuth = sazi(sda, hr+sta); |
416 |
/* convert measured values */ |
417 |
if (dir_is_horiz && altitude > 0.) |
418 |
dir /= sin(altitude); |
419 |
if (input == 1) { |
420 |
dir_irrad = dir; |
421 |
diff_irrad = dif; |
422 |
} else /* input == 2 */ { |
423 |
dir_illum = dir; |
424 |
diff_illum = dif; |
425 |
} |
426 |
/* compute sky patch values */ |
427 |
ComputeSky(mtx_data+mtx_offset); |
428 |
if (do_sun) |
429 |
AddDirect(mtx_data+mtx_offset); |
430 |
} |
431 |
/* check for junk at end */ |
432 |
while ((i = fgetc(stdin)) != EOF) |
433 |
if (!isspace(i)) { |
434 |
fprintf(stderr, "%s: warning - unexpected data past EOT: ", |
435 |
progname); |
436 |
buf[0] = i; buf[1] = '\0'; |
437 |
fgets(buf+1, sizeof(buf)-1, stdin); |
438 |
fputs(buf, stderr); fputc('\n', stderr); |
439 |
break; |
440 |
} |
441 |
/* write out matrix */ |
442 |
#ifdef getc_unlocked |
443 |
flockfile(stdout); |
444 |
#endif |
445 |
if (verbose) |
446 |
fprintf(stderr, "%s: writing %smatrix with %d time steps...\n", |
447 |
progname, outfmt=='a' ? "" : "binary ", ntsteps); |
448 |
/* patches are rows (outer sort) */ |
449 |
for (i = 0; i < nskypatch; i++) { |
450 |
mtx_offset = 3*i; |
451 |
switch (outfmt) { |
452 |
case 'a': |
453 |
for (j = 0; j < ntsteps; j++) { |
454 |
printf("%.3e %.3e %.3e\n", mtx_data[mtx_offset], |
455 |
mtx_data[mtx_offset+1], |
456 |
mtx_data[mtx_offset+2]); |
457 |
mtx_offset += 3*nskypatch; |
458 |
} |
459 |
fputc('\n', stdout); |
460 |
break; |
461 |
case 'f': |
462 |
for (j = 0; j < ntsteps; j++) { |
463 |
fwrite(mtx_data+mtx_offset, sizeof(float), 3, |
464 |
stdout); |
465 |
mtx_offset += 3*nskypatch; |
466 |
} |
467 |
break; |
468 |
case 'd': |
469 |
for (j = 0; j < ntsteps; j++) { |
470 |
double ment[3]; |
471 |
ment[0] = mtx_data[mtx_offset]; |
472 |
ment[1] = mtx_data[mtx_offset+1]; |
473 |
ment[2] = mtx_data[mtx_offset+2]; |
474 |
fwrite(ment, sizeof(double), 3, stdout); |
475 |
mtx_offset += 3*nskypatch; |
476 |
} |
477 |
break; |
478 |
} |
479 |
if (ferror(stdout)) |
480 |
goto writerr; |
481 |
} |
482 |
if (fflush(stdout) == EOF) |
483 |
goto writerr; |
484 |
if (verbose) |
485 |
fprintf(stderr, "%s: done.\n", progname); |
486 |
exit(0); |
487 |
userr: |
488 |
fprintf(stderr, "Usage: %s [-v][-d|-s][-m N][-g refl][-c r g b][-o{f|d}] [tape.wea]\n", |
489 |
progname); |
490 |
exit(1); |
491 |
fmterr: |
492 |
fprintf(stderr, "%s: input weather tape format error\n", progname); |
493 |
exit(1); |
494 |
writerr: |
495 |
fprintf(stderr, "%s: write error on output\n", progname); |
496 |
exit(1); |
497 |
} |
498 |
|
499 |
/* Return maximum of two doubles */ |
500 |
double dmax( double a, double b ) |
501 |
{ return (a > b) ? a : b; } |
502 |
|
503 |
/* Compute sky patch radiance values (modified by GW) */ |
504 |
void |
505 |
ComputeSky(float *parr) |
506 |
{ |
507 |
int index; /* Category index */ |
508 |
double norm_diff_illum; /* Normalized diffuse illuimnance */ |
509 |
double zlumin; /* Zenith luminance */ |
510 |
int i; |
511 |
|
512 |
if (bright(skycolor) <= 1e-4) { /* 0 sky component? */ |
513 |
memset(parr, 0, sizeof(float)*3*nskypatch); |
514 |
return; |
515 |
} |
516 |
|
517 |
/* Calculate atmospheric precipitable water content */ |
518 |
apwc = CalcPrecipWater(dew_point); |
519 |
|
520 |
/* Limit solar altitude to keep circumsolar off zenith */ |
521 |
if (altitude > DegToRad(87.0)) |
522 |
altitude = DegToRad(87.0); |
523 |
|
524 |
/* Calculate sun zenith angle */ |
525 |
sun_zenith = DegToRad(90.0) - altitude; |
526 |
|
527 |
/* Compute the inputs for the calculation of the sky distribution */ |
528 |
|
529 |
if (input == 0) /* XXX never used */ |
530 |
{ |
531 |
/* Calculate irradiance */ |
532 |
diff_irrad = CalcDiffuseIrradiance(); |
533 |
dir_irrad = CalcDirectIrradiance(); |
534 |
|
535 |
/* Calculate illuminance */ |
536 |
index = GetCategoryIndex(); |
537 |
diff_illum = diff_irrad * CalcDiffuseIllumRatio(index); |
538 |
dir_illum = dir_irrad * CalcDirectIllumRatio(index); |
539 |
} |
540 |
else if (input == 1) |
541 |
{ |
542 |
sky_brightness = CalcSkyBrightness(); |
543 |
sky_clearness = CalcSkyClearness(); |
544 |
|
545 |
/* Calculate illuminance */ |
546 |
index = GetCategoryIndex(); |
547 |
diff_illum = diff_irrad * CalcDiffuseIllumRatio(index); |
548 |
dir_illum = dir_irrad * CalcDirectIllumRatio(index); |
549 |
} |
550 |
else if (input == 2) |
551 |
{ |
552 |
/* Calculate sky brightness and clearness from illuminance values */ |
553 |
index = CalcSkyParamFromIllum(); |
554 |
} |
555 |
|
556 |
/* Compute ground radiance (include solar contribution if any) */ |
557 |
parr[0] = diff_illum * (1./PI/WHTEFFICACY); |
558 |
if (altitude > 0) |
559 |
parr[0] += dir_illum * sin(altitude) * (1./PI/WHTEFFICACY); |
560 |
parr[2] = parr[1] = parr[0]; |
561 |
|
562 |
/* Calculate Perez sky model parameters */ |
563 |
CalcPerezParam(sun_zenith, sky_clearness, sky_brightness, index); |
564 |
|
565 |
/* Calculate sky patch luminance values */ |
566 |
CalcSkyPatchLumin(parr); |
567 |
|
568 |
/* Calculate relative horizontal illuminance */ |
569 |
norm_diff_illum = CalcRelHorzIllum(parr); |
570 |
|
571 |
/* Normalization coefficient */ |
572 |
norm_diff_illum = diff_illum / norm_diff_illum; |
573 |
|
574 |
/* Calculate relative zenith luminance */ |
575 |
zlumin = CalcRelLuminance(sun_zenith, 0.0); |
576 |
|
577 |
/* Calculate absolute zenith illuminance */ |
578 |
zlumin *= norm_diff_illum; |
579 |
|
580 |
/* Apply to sky patches to get absolute radiance values */ |
581 |
for (i = 1; i < nskypatch; i++) { |
582 |
scalecolor(parr+3*i, zlumin*(1./WHTEFFICACY)); |
583 |
multcolor(parr+3*i, skycolor); |
584 |
} |
585 |
} |
586 |
|
587 |
/* Add in solar direct to nearest sky patches (GW) */ |
588 |
void |
589 |
AddDirect(float *parr) |
590 |
{ |
591 |
FVECT svec; |
592 |
double near_dprod[4]; |
593 |
int near_patch[4]; |
594 |
double wta[4], wtot; |
595 |
int i, j, p; |
596 |
|
597 |
if (!do_sun || dir_illum < 1e-4) |
598 |
return; |
599 |
/* identify 4 closest patches */ |
600 |
for (i = 4; i--; ) |
601 |
near_dprod[i] = -1.; |
602 |
vector(svec, altitude, azimuth); |
603 |
for (p = 1; p < nskypatch; p++) { |
604 |
FVECT pvec; |
605 |
double dprod; |
606 |
rh_vector(pvec, p); |
607 |
dprod = DOT(pvec, svec); |
608 |
for (i = 0; i < 4; i++) |
609 |
if (dprod > near_dprod[i]) { |
610 |
for (j = 4; --j > i; ) { |
611 |
near_dprod[j] = near_dprod[j-1]; |
612 |
near_patch[j] = near_patch[j-1]; |
613 |
} |
614 |
near_dprod[i] = dprod; |
615 |
near_patch[i] = p; |
616 |
break; |
617 |
} |
618 |
} |
619 |
wtot = 0; /* weight by proximity */ |
620 |
for (i = 4; i--; ) |
621 |
wtot += wta[i] = 1./(1.002 - near_dprod[i]); |
622 |
/* add to nearest patch radiances */ |
623 |
for (i = 4; i--; ) |
624 |
parr[near_patch[i]] += wta[i] * dir_illum / |
625 |
(wtot * rh_dom[near_patch[i]]); |
626 |
} |
627 |
|
628 |
/* Initialize Reinhart sky patch positions (GW) */ |
629 |
int |
630 |
rh_init(void) |
631 |
{ |
632 |
#define NROW 7 |
633 |
static const int tnaz[NROW] = {30, 30, 24, 24, 18, 12, 6}; |
634 |
const double alpha = (PI/2.)/(NROW*rhsubdiv + .5); |
635 |
int p, i, j; |
636 |
/* allocate patch angle arrays */ |
637 |
nskypatch = 0; |
638 |
for (p = 0; p < NROW; p++) |
639 |
nskypatch += tnaz[p]; |
640 |
nskypatch *= rhsubdiv*rhsubdiv; |
641 |
nskypatch += 2; |
642 |
rh_palt = (float *)malloc(sizeof(float)*nskypatch); |
643 |
rh_pazi = (float *)malloc(sizeof(float)*nskypatch); |
644 |
rh_dom = (float *)malloc(sizeof(float)*nskypatch); |
645 |
if ((rh_palt == NULL) | (rh_pazi == NULL) | (rh_dom == NULL)) { |
646 |
fprintf(stderr, "%s: out of memory in rh_init()\n", progname); |
647 |
exit(1); |
648 |
} |
649 |
rh_palt[0] = -PI/2.; /* ground & zenith patches */ |
650 |
rh_pazi[0] = 0.; |
651 |
rh_dom[0] = 2.*PI; |
652 |
rh_palt[nskypatch-1] = PI/2.; |
653 |
rh_pazi[nskypatch-1] = 0.; |
654 |
rh_dom[nskypatch-1] = 2.*PI*(1. - cos(alpha*.5)); |
655 |
p = 1; /* "normal" patches */ |
656 |
for (i = 0; i < NROW*rhsubdiv; i++) { |
657 |
const float ralt = alpha*(i + .5); |
658 |
const int ninrow = tnaz[i/rhsubdiv]*rhsubdiv; |
659 |
const float dom = (sin(alpha*(i+1)) - sin(alpha*i))/ninrow; |
660 |
for (j = 0; j < ninrow; j++) { |
661 |
rh_palt[p] = ralt; |
662 |
rh_pazi[p] = 2.*PI * j / (double)ninrow; |
663 |
rh_dom[p++] = dom; |
664 |
} |
665 |
} |
666 |
return nskypatch; |
667 |
#undef NROW |
668 |
} |
669 |
|
670 |
/* Resize daylight matrix (GW) */ |
671 |
float * |
672 |
resize_dmatrix(float *mtx_data, int nsteps, int npatch) |
673 |
{ |
674 |
if (mtx_data == NULL) |
675 |
mtx_data = (float *)malloc(sizeof(float)*3*nsteps*npatch); |
676 |
else |
677 |
mtx_data = (float *)realloc(mtx_data, |
678 |
sizeof(float)*3*nsteps*npatch); |
679 |
if (mtx_data == NULL) { |
680 |
fprintf(stderr, "%s: out of memory in resize_dmatrix(%d,%d)\n", |
681 |
progname, nsteps, npatch); |
682 |
exit(1); |
683 |
} |
684 |
return(mtx_data); |
685 |
} |
686 |
|
687 |
/* Determine category index */ |
688 |
int GetCategoryIndex() |
689 |
{ |
690 |
int index; /* Loop index */ |
691 |
|
692 |
for (index = 0; index < 8; index++) |
693 |
if ((sky_clearness >= SkyClearCat[index].lower) && |
694 |
(sky_clearness < SkyClearCat[index].upper)) |
695 |
break; |
696 |
|
697 |
return index; |
698 |
} |
699 |
|
700 |
/* Calculate diffuse illuminance to diffuse irradiance ratio */ |
701 |
|
702 |
/* Reference: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. */ |
703 |
/* Stewart. 1990. ìModeling Daylight Availability and */ |
704 |
/* Irradiance Components from Direct and Global */ |
705 |
/* Irradiance,î Solar Energy 44(5):271-289, Eqn. 7. */ |
706 |
|
707 |
double CalcDiffuseIllumRatio( int index ) |
708 |
{ |
709 |
ModelCoeff const *pnle; /* Category coefficient pointer */ |
710 |
|
711 |
/* Get category coefficient pointer */ |
712 |
pnle = &(DiffuseLumEff[index]); |
713 |
|
714 |
return pnle->a + pnle->b * apwc + pnle->c * cos(sun_zenith) + |
715 |
pnle->d * log(sky_brightness); |
716 |
} |
717 |
|
718 |
/* Calculate direct illuminance to direct irradiance ratio */ |
719 |
|
720 |
/* Reference: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. */ |
721 |
/* Stewart. 1990. ìModeling Daylight Availability and */ |
722 |
/* Irradiance Components from Direct and Global */ |
723 |
/* Irradiance,î Solar Energy 44(5):271-289, Eqn. 8. */ |
724 |
|
725 |
double CalcDirectIllumRatio( int index ) |
726 |
{ |
727 |
ModelCoeff const *pnle; /* Category coefficient pointer */ |
728 |
|
729 |
/* Get category coefficient pointer */ |
730 |
pnle = &(DirectLumEff[index]); |
731 |
|
732 |
/* Calculate direct illuminance from direct irradiance */ |
733 |
|
734 |
return dmax((pnle->a + pnle->b * apwc + pnle->c * exp(5.73 * |
735 |
sun_zenith - 5.0) + pnle->d * sky_brightness), |
736 |
0.0); |
737 |
} |
738 |
|
739 |
/* Calculate sky brightness */ |
740 |
|
741 |
/* Reference: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. */ |
742 |
/* Stewart. 1990. ìModeling Daylight Availability and */ |
743 |
/* Irradiance Components from Direct and Global */ |
744 |
/* Irradiance,î Solar Energy 44(5):271-289, Eqn. 2. */ |
745 |
|
746 |
double CalcSkyBrightness() |
747 |
{ |
748 |
return diff_irrad * CalcAirMass() / (DC_SolarConstantE * |
749 |
CalcEccentricity()); |
750 |
} |
751 |
|
752 |
/* Calculate sky clearness */ |
753 |
|
754 |
/* Reference: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. */ |
755 |
/* Stewart. 1990. ìModeling Daylight Availability and */ |
756 |
/* Irradiance Components from Direct and Global */ |
757 |
/* Irradiance,î Solar Energy 44(5):271-289, Eqn. 1. */ |
758 |
|
759 |
double CalcSkyClearness() |
760 |
{ |
761 |
double sz_cubed; /* Sun zenith angle cubed */ |
762 |
|
763 |
/* Calculate sun zenith angle cubed */ |
764 |
sz_cubed = pow(sun_zenith, 3.0); |
765 |
|
766 |
return ((diff_irrad + dir_irrad) / diff_irrad + 1.041 * |
767 |
sz_cubed) / (1.0 + 1.041 * sz_cubed); |
768 |
} |
769 |
|
770 |
/* Calculate diffuse horizontal irradiance from Perez sky brightness */ |
771 |
|
772 |
/* Reference: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. */ |
773 |
/* Stewart. 1990. ìModeling Daylight Availability and */ |
774 |
/* Irradiance Components from Direct and Global */ |
775 |
/* Irradiance,î Solar Energy 44(5):271-289, Eqn. 2 */ |
776 |
/* (inverse). */ |
777 |
|
778 |
double CalcDiffuseIrradiance() |
779 |
{ |
780 |
return sky_brightness * DC_SolarConstantE * CalcEccentricity() / |
781 |
CalcAirMass(); |
782 |
} |
783 |
|
784 |
/* Calculate direct normal irradiance from Perez sky clearness */ |
785 |
|
786 |
/* Reference: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. */ |
787 |
/* Stewart. 1990. ìModeling Daylight Availability and */ |
788 |
/* Irradiance Components from Direct and Global */ |
789 |
/* Irradiance,î Solar Energy 44(5):271-289, Eqn. 1 */ |
790 |
/* (inverse). */ |
791 |
|
792 |
double CalcDirectIrradiance() |
793 |
{ |
794 |
return CalcDiffuseIrradiance() * ((sky_clearness - 1.0) * (1 + 1.041 |
795 |
* pow(sun_zenith, 3.0))); |
796 |
} |
797 |
|
798 |
/* Calculate sky brightness and clearness from illuminance values */ |
799 |
int CalcSkyParamFromIllum() |
800 |
{ |
801 |
double test1 = 0.1; |
802 |
double test2 = 0.1; |
803 |
int counter = 0; |
804 |
int index = 0; /* Category index */ |
805 |
|
806 |
/* Convert illuminance to irradiance */ |
807 |
diff_irrad = diff_illum * DC_SolarConstantE / |
808 |
(DC_SolarConstantL * 1000.0); |
809 |
dir_irrad = dir_illum * DC_SolarConstantE / |
810 |
(DC_SolarConstantL * 1000.0); |
811 |
|
812 |
/* Calculate sky brightness and clearness */ |
813 |
sky_brightness = CalcSkyBrightness(); |
814 |
sky_clearness = CalcSkyClearness(); |
815 |
|
816 |
/* Limit sky clearness */ |
817 |
if (sky_clearness > 12.0) |
818 |
sky_clearness = 12.0; |
819 |
|
820 |
/* Limit sky brightness */ |
821 |
if (sky_brightness < 0.05) |
822 |
sky_brightness = 0.01; |
823 |
|
824 |
while (((fabs(diff_irrad - test1) > 10.0) || |
825 |
(fabs(dir_irrad - test2) > 10.0)) && !(counter == 5)) |
826 |
{ |
827 |
test1 = diff_irrad; |
828 |
test2 = dir_irrad; |
829 |
counter++; |
830 |
|
831 |
/* Convert illuminance to irradiance */ |
832 |
index = GetCategoryIndex(); |
833 |
diff_irrad = diff_illum / CalcDiffuseIllumRatio(index); |
834 |
dir_irrad = dir_illum / CalcDirectIllumRatio(index); |
835 |
|
836 |
/* Calculate sky brightness and clearness */ |
837 |
sky_brightness = CalcSkyBrightness(); |
838 |
sky_clearness = CalcSkyClearness(); |
839 |
|
840 |
/* Limit sky clearness */ |
841 |
if (sky_clearness > 12.0) |
842 |
sky_clearness = 12.0; |
843 |
|
844 |
/* Limit sky brightness */ |
845 |
if (sky_brightness < 0.05) |
846 |
sky_brightness = 0.01; |
847 |
} |
848 |
|
849 |
return GetCategoryIndex(); |
850 |
} |
851 |
|
852 |
/* Calculate relative luminance */ |
853 |
|
854 |
/* Reference: Perez, R., R. Seals, and J. Michalsky. 1993. */ |
855 |
/* ìAll-Weather Model for Sky Luminance Distribution - */ |
856 |
/* Preliminary Configuration and Validation,î Solar Energy */ |
857 |
/* 50(3):235-245, Eqn. 1. */ |
858 |
|
859 |
double CalcRelLuminance( double gamma, double zeta ) |
860 |
{ |
861 |
return (1.0 + perez_param[0] * exp(perez_param[1] / cos(zeta))) * |
862 |
(1.0 + perez_param[2] * exp(perez_param[3] * gamma) + |
863 |
perez_param[4] * cos(gamma) * cos(gamma)); |
864 |
} |
865 |
|
866 |
/* Calculate Perez sky model parameters */ |
867 |
|
868 |
/* Reference: Perez, R., R. Seals, and J. Michalsky. 1993. */ |
869 |
/* ìAll-Weather Model for Sky Luminance Distribution - */ |
870 |
/* Preliminary Configuration and Validation,î Solar Energy */ |
871 |
/* 50(3):235-245, Eqns. 6 - 8. */ |
872 |
|
873 |
void CalcPerezParam( double sz, double epsilon, double delta, |
874 |
int index ) |
875 |
{ |
876 |
double x[5][4]; /* Coefficents a, b, c, d, e */ |
877 |
int i, j; /* Loop indices */ |
878 |
|
879 |
/* Limit sky brightness */ |
880 |
if (epsilon > 1.065 && epsilon < 2.8) |
881 |
{ |
882 |
if (delta < 0.2) |
883 |
delta = 0.2; |
884 |
} |
885 |
|
886 |
/* Get Perez coefficients */ |
887 |
for (i = 0; i < 5; i++) |
888 |
for (j = 0; j < 4; j++) |
889 |
x[i][j] = PerezCoeff[index][4 * i + j]; |
890 |
|
891 |
if (index != 0) |
892 |
{ |
893 |
/* Calculate parameter a, b, c, d and e (Eqn. 6) */ |
894 |
for (i = 0; i < 5; i++) |
895 |
perez_param[i] = x[i][0] + x[i][1] * sz + delta * (x[i][2] + |
896 |
x[i][3] * sz); |
897 |
} |
898 |
else |
899 |
{ |
900 |
/* Parameters a, b and e (Eqn. 6) */ |
901 |
perez_param[0] = x[0][0] + x[0][1] * sz + delta * (x[0][2] + |
902 |
x[0][3] * sz); |
903 |
perez_param[1] = x[1][0] + x[1][1] * sz + delta * (x[1][2] + |
904 |
x[1][3] * sz); |
905 |
perez_param[4] = x[4][0] + x[4][1] * sz + delta * (x[4][2] + |
906 |
x[4][3] * sz); |
907 |
|
908 |
/* Parameter c (Eqn. 7) */ |
909 |
perez_param[2] = exp(pow(delta * (x[2][0] + x[2][1] * sz), |
910 |
x[2][2])) - x[2][3]; |
911 |
|
912 |
/* Parameter d (Eqn. 8) */ |
913 |
perez_param[3] = -exp(delta * (x[3][0] + x[3][1] * sz)) + |
914 |
x[3][2] + delta * x[3][3]; |
915 |
} |
916 |
} |
917 |
|
918 |
/* Calculate relative horizontal illuminance (modified by GW) */ |
919 |
|
920 |
/* Reference: Perez, R., R. Seals, and J. Michalsky. 1993. */ |
921 |
/* ìAll-Weather Model for Sky Luminance Distribution - */ |
922 |
/* Preliminary Configuration and Validation,î Solar Energy */ |
923 |
/* 50(3):235-245, Eqn. 3. */ |
924 |
|
925 |
double CalcRelHorzIllum( float *parr ) |
926 |
{ |
927 |
int i; |
928 |
double rh_illum = 0.0; /* Relative horizontal illuminance */ |
929 |
|
930 |
for (i = 1; i < nskypatch; i++) |
931 |
rh_illum += parr[3*i+1] * rh_cos(i); |
932 |
|
933 |
return rh_illum * (2.0 * PI / (nskypatch-1)); |
934 |
} |
935 |
|
936 |
/* Calculate earth orbit eccentricity correction factor */ |
937 |
|
938 |
/* Reference: Sen, Z. 2008. Solar Energy Fundamental and Modeling */ |
939 |
/* Techniques. Springer, p. 72. */ |
940 |
|
941 |
double CalcEccentricity() |
942 |
{ |
943 |
double day_angle; /* Day angle (radians) */ |
944 |
double E0; /* Eccentricity */ |
945 |
|
946 |
/* Calculate day angle */ |
947 |
day_angle = (julian_date - 1.0) * (2.0 * PI / 365.0); |
948 |
|
949 |
/* Calculate eccentricity */ |
950 |
E0 = 1.00011 + 0.034221 * cos(day_angle) + 0.00128 * sin(day_angle) |
951 |
+ 0.000719 * cos(2.0 * day_angle) + 0.000077 * sin(2.0 * |
952 |
day_angle); |
953 |
|
954 |
return E0; |
955 |
} |
956 |
|
957 |
/* Calculate atmospheric precipitable water content */ |
958 |
|
959 |
/* Reference: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. */ |
960 |
/* Stewart. 1990. ìModeling Daylight Availability and */ |
961 |
/* Irradiance Components from Direct and Global */ |
962 |
/* Irradiance,î Solar Energy 44(5):271-289, Eqn. 3. */ |
963 |
|
964 |
/* Note: The default surface dew point temperature is 11 deg. C */ |
965 |
/* (52 deg. F). Typical values are: */ |
966 |
|
967 |
/* Celsius Fahrenheit Human Perception */ |
968 |
/* > 24 > 75 Extremely uncomfortable */ |
969 |
/* 21 - 24 70 - 74 Very humid */ |
970 |
/* 18 - 21 65 - 69 Somewhat uncomfortable */ |
971 |
/* 16 - 18 60 - 64 OK for most people */ |
972 |
/* 13 - 16 55 - 59 Comfortable */ |
973 |
/* 10 - 12 50 - 54 Very comfortable */ |
974 |
/* < 10 < 49 A bit dry for some */ |
975 |
|
976 |
double CalcPrecipWater( double dpt ) |
977 |
{ return exp(0.07 * dpt - 0.075); } |
978 |
|
979 |
/* Calculate relative air mass */ |
980 |
|
981 |
/* Reference: Kasten, F. 1966. "A New Table and Approximation Formula */ |
982 |
/* for the Relative Optical Air Mass," Arch. Meteorol. */ |
983 |
/* Geophys. Bioklimataol. Ser. B14, pp. 206-233. */ |
984 |
|
985 |
/* Note: More sophisticated relative air mass models are */ |
986 |
/* available, but they differ significantly only for */ |
987 |
/* sun zenith angles greater than 80 degrees. */ |
988 |
|
989 |
double CalcAirMass() |
990 |
{ |
991 |
return (1.0 / (cos(sun_zenith) + 0.15 * pow(93.885 - |
992 |
RadToDeg(sun_zenith), -1.253))); |
993 |
} |
994 |
|
995 |
/* Calculate Perez All-Weather sky patch luminances (modified by GW) */ |
996 |
|
997 |
/* NOTE: The sky patches centers are determined in accordance with the */ |
998 |
/* BRE-IDMP sky luminance measurement procedures. (See for example */ |
999 |
/* Mardaljevic, J. 2001. "The BRE-IDMP Dataset: A New Benchmark */ |
1000 |
/* for the Validation of Illuminance Prediction Techniques," */ |
1001 |
/* Lighting Research & Technology 33(2):117-136.) */ |
1002 |
|
1003 |
void CalcSkyPatchLumin( float *parr ) |
1004 |
{ |
1005 |
int i; |
1006 |
double aas; /* Sun-sky point azimuthal angle */ |
1007 |
double sspa; /* Sun-sky point angle */ |
1008 |
double zsa; /* Zenithal sun angle */ |
1009 |
|
1010 |
for (i = 1; i < nskypatch; i++) |
1011 |
{ |
1012 |
/* Calculate sun-sky point azimuthal angle */ |
1013 |
aas = fabs(rh_pazi[i] - azimuth); |
1014 |
|
1015 |
/* Calculate zenithal sun angle */ |
1016 |
zsa = PI * 0.5 - rh_palt[i]; |
1017 |
|
1018 |
/* Calculate sun-sky point angle (Equation 8-20) */ |
1019 |
sspa = acos(cos(sun_zenith) * cos(zsa) + sin(sun_zenith) * |
1020 |
sin(zsa) * cos(aas)); |
1021 |
|
1022 |
/* Calculate patch luminance */ |
1023 |
parr[3*i] = CalcRelLuminance(sspa, zsa); |
1024 |
if (parr[3*i] < 0) parr[3*i] = 0; |
1025 |
parr[3*i+2] = parr[3*i+1] = parr[3*i]; |
1026 |
} |
1027 |
} |