1 /**************************************************************************
2 * sky.c -- model sky with an upside down "bowl"
4 * Written by Curtis Olson, started December 1997.
6 * Copyright (C) 1997 Curtis L. Olson - curt@infoplane.com
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License as
10 * published by the Free Software Foundation; either version 2 of the
11 * License, or (at your option) any later version.
13 * This program is distributed in the hope that it will be useful, but
14 * WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
23 * (Log is kept at end of this file)
24 **************************************************************************/
39 #include "../XGL/xgl.h"
43 #include "../Time/fg_time.h"
45 #include "../Aircraft/aircraft.h"
46 #include "../Flight/flight.h"
47 #include "../Include/constants.h"
48 #include "../Main/views.h"
49 #include "../Math/fg_random.h"
51 #include "../Include/general.h"
54 /* in meters of course */
55 #define CENTER_ELEV 25000.0
56 #define INNER_RADIUS 50000.0
57 #define INNER_ELEV 20000.0
58 #define MIDDLE_RADIUS 70000.0
59 #define MIDDLE_ELEV 8000.0
60 #define OUTER_RADIUS 80000.0
61 #define OUTER_ELEV 0.0
64 static float inner_vertex[12][3];
65 static float middle_vertex[12][3];
66 static float outer_vertex[12][3];
68 static float inner_color[12][4];
69 static float middle_color[12][4];
70 static float outer_color[12][4];
73 /* Calculate the sky structure vertices */
74 void fgSkyVerticesInit() {
78 printf("Generating the sky dome vertices.\n");
80 for ( i = 0; i < 12; i++ ) {
81 theta = (i * 30.0) * DEG_TO_RAD;
83 inner_vertex[i][0] = cos(theta) * INNER_RADIUS;
84 inner_vertex[i][1] = sin(theta) * INNER_RADIUS;
85 inner_vertex[i][2] = INNER_ELEV;
87 printf(" %.2f %.2f\n", cos(theta) * INNER_RADIUS,
88 sin(theta) * INNER_RADIUS);
90 middle_vertex[i][0] = cos((double)theta) * MIDDLE_RADIUS;
91 middle_vertex[i][1] = sin((double)theta) * MIDDLE_RADIUS;
92 middle_vertex[i][2] = MIDDLE_ELEV;
94 outer_vertex[i][0] = cos((double)theta) * OUTER_RADIUS;
95 outer_vertex[i][1] = sin((double)theta) * OUTER_RADIUS;
96 outer_vertex[i][2] = OUTER_ELEV;
102 /* (Re)calculate the sky colors at each vertex */
103 void fgSkyColorsInit() {
105 float sun_angle, diff;
106 float outer_param[3], outer_amt[3], outer_diff[3];
107 float middle_param[3], middle_amt[3], middle_diff[3];
110 l = &cur_light_params;
112 printf("Generating the sky colors for each vertex.\n");
114 /* setup for the possibility of sunset effects */
115 sun_angle = l->sun_angle * RAD_TO_DEG;
116 printf(" Sun angle in degrees = %.2f\n", sun_angle);
118 if ( (sun_angle > 80.0) && (sun_angle < 100.0) ) {
120 outer_param[0] = (10.0 - fabs(90.0 - sun_angle)) / 25.0;
121 outer_param[1] = (10.0 - fabs(90.0 - sun_angle)) / 45.0;
122 outer_param[2] = 0.0;
124 middle_param[0] = (10.0 - fabs(90.0 - sun_angle)) / 40.0;
125 middle_param[1] = (10.0 - fabs(90.0 - sun_angle)) / 60.0;
126 middle_param[2] = 0.0;
128 outer_diff[0] = outer_param[0] / 6.0;
129 outer_diff[1] = outer_param[1] / 6.0;
130 outer_diff[2] = outer_param[2] / 6.0;
132 middle_diff[0] = middle_param[0] / 6.0;
133 middle_diff[1] = middle_param[1] / 6.0;
134 middle_diff[2] = middle_param[2] / 6.0;
136 outer_param[0] = outer_param[1] = outer_param[2] = 0.0;
137 middle_param[0] = middle_param[1] = middle_param[2] = 0.0;
139 outer_diff[0] = outer_diff[1] = outer_diff[2] = 0.0;
140 middle_diff[0] = middle_diff[1] = middle_diff[2] = 0.0;
142 /* printf(" outer_red_param = %.2f outer_red_diff = %.2f\n",
143 outer_red_param, outer_red_diff); */
145 /* calculate transition colors between sky and fog */
146 for ( j = 0; j < 3; j++ ) {
147 outer_amt[j] = outer_param[j];
148 middle_amt[j] = middle_param[j];
151 for ( i = 0; i < 6; i++ ) {
152 for ( j = 0; j < 3; j++ ) {
153 diff = l->sky_color[j] - l->fog_color[j];
155 inner_color[i][j] = l->sky_color[j] - diff * 0.3;
156 middle_color[i][j] = l->sky_color[j] - diff * 0.9 + middle_amt[j];
157 outer_color[i][j] = l->fog_color[j] + outer_amt[j];
159 if ( middle_color[i][j] > 1.00 ) { middle_color[i][j] = 1.00; }
160 if ( middle_color[i][j] < 0.10 ) { middle_color[i][j] = 0.10; }
161 if ( outer_color[i][j] > 1.00 ) { outer_color[i][j] = 1.00; }
162 if ( outer_color[i][j] < 0.10 ) { outer_color[i][j] = 0.10; }
164 inner_color[i][3] = middle_color[i][3] = outer_color[i][3] =
167 for ( j = 0; j < 3; j++ ) {
168 outer_amt[j] -= outer_diff[j];
169 middle_amt[j] -= middle_diff[j];
172 printf("inner_color[%d] = %.2f %.2f %.2f %.2f\n", i, inner_color[i][0],
173 inner_color[i][1], inner_color[i][2], inner_color[i][3]);
174 printf("middle_color[%d] = %.2f %.2f %.2f %.2f\n", i,
175 middle_color[i][0], middle_color[i][1], middle_color[i][2],
177 printf("outer_color[%d] = %.2f %.2f %.2f %.2f\n", i,
178 outer_color[i][0], outer_color[i][1], outer_color[i][2],
182 for ( j = 0; j < 3; j++ ) {
187 for ( i = 6; i < 12; i++ ) {
189 for ( j = 0; j < 3; j++ ) {
190 diff = l->sky_color[j] - l->fog_color[j];
192 inner_color[i][j] = l->sky_color[j] - diff * 0.3;
193 middle_color[i][j] = l->sky_color[j] - diff * 0.9 + middle_amt[j];
194 outer_color[i][j] = l->fog_color[j] + outer_amt[j];
196 if ( middle_color[i][j] > 1.00 ) { middle_color[i][j] = 1.00; }
197 if ( middle_color[i][j] < 0.10 ) { middle_color[i][j] = 0.10; }
198 if ( outer_color[i][j] > 1.00 ) { outer_color[i][j] = 1.00; }
199 if ( outer_color[i][j] < 0.15 ) { outer_color[i][j] = 0.15; }
201 inner_color[i][3] = middle_color[i][3] = outer_color[i][3] =
204 for ( j = 0; j < 3; j++ ) {
205 outer_amt[j] += outer_diff[j];
206 middle_amt[j] += middle_diff[j];
209 printf("inner_color[%d] = %.2f %.2f %.2f %.2f\n", i, inner_color[i][0],
210 inner_color[i][1], inner_color[i][2], inner_color[i][3]);
211 printf("middle_color[%d] = %.2f %.2f %.2f %.2f\n", i,
212 middle_color[i][0], middle_color[i][1], middle_color[i][2],
214 printf("outer_color[%d] = %.2f %.2f %.2f %.2f\n", i,
215 outer_color[i][0], outer_color[i][1], outer_color[i][2],
221 /* Initialize the sky structure and colors */
233 float /* inner_color[4], middle_color[4], diff, */ east_dot, dot, angle;
236 f = ¤t_aircraft.flight;
237 l = &cur_light_params;
240 printf("Rendering the sky.\n");
244 /* calculate the angle between v->surface_to_sun and
245 * v->surface_east. We do this so we can sort out the acos()
246 * ambiguity. I wish I could think of a more efficient way ... :-( */
247 east_dot = MAT3_DOT_PRODUCT(v->surface_to_sun, v->surface_east);
248 printf(" East dot product = %.2f\n", east_dot);
250 /* calculate the angle between v->surface_to_sun and
251 * v->surface_south. this is how much we have to rotate the sky
252 * for it to align with the sun */
253 dot = MAT3_DOT_PRODUCT(v->surface_to_sun, v->surface_south);
254 printf(" Dot product = %.2f\n", dot);
255 if ( east_dot >= 0 ) {
260 printf(" Sky needs to rotate = %.3f rads = %.1f degrees.\n",
261 angle, angle * RAD_TO_DEG);
263 /* Translate to view position */
264 xglTranslatef( v->cur_zero_elev.x, v->cur_zero_elev.y, v->cur_zero_elev.z );
265 /* printf(" Translated to %.2f %.2f %.2f\n",
266 v->cur_zero_elev.x, v->cur_zero_elev.y, v->cur_zero_elev.z ); */
268 /* Rotate to proper orientation */
269 printf(" lon = %.2f lat = %.2f\n", FG_Longitude * RAD_TO_DEG,
270 FG_Latitude * RAD_TO_DEG);
271 xglRotatef( FG_Longitude * RAD_TO_DEG, 0.0, 0.0, 1.0 );
272 xglRotatef( 90.0 - FG_Latitude * RAD_TO_DEG, 0.0, 1.0, 0.0 );
273 xglRotatef( angle * RAD_TO_DEG, 0.0, 0.0, 1.0 );
275 /* Draw inner/center section of sky*/
276 xglBegin( GL_TRIANGLE_FAN );
277 xglColor4fv(l->sky_color);
278 xglVertex3f(0.0, 0.0, CENTER_ELEV);
279 for ( i = 0; i < 12; i++ ) {
280 xglColor4fv( inner_color[i] );
281 xglVertex3fv( inner_vertex[i] );
283 xglColor4fv( inner_color[0] );
284 xglVertex3fv( inner_vertex[0] );
287 /* Draw the middle ring */
288 xglBegin( GL_TRIANGLE_STRIP );
289 for ( i = 0; i < 12; i++ ) {
290 xglColor4fv( middle_color[i] );
291 xglVertex3fv( middle_vertex[i] );
292 xglColor4fv( inner_color[i] );
293 xglVertex3fv( inner_vertex[i] );
295 xglColor4fv( middle_color[0] );
296 /* xglColor4f(1.0, 0.0, 0.0, 1.0); */
297 xglVertex3fv( middle_vertex[0] );
298 xglColor4fv( inner_color[0] );
299 /* xglColor4f(1.0, 0.0, 0.0, 1.0); */
300 xglVertex3fv( inner_vertex[0] );
303 /* Draw the outer ring */
304 xglBegin( GL_TRIANGLE_STRIP );
305 for ( i = 0; i < 12; i++ ) {
306 xglColor4fv( outer_color[i] );
307 xglVertex3fv( outer_vertex[i] );
308 xglColor4fv( middle_color[i] );
309 xglVertex3fv( middle_vertex[i] );
311 xglColor4fv( outer_color[0] );
312 xglVertex3fv( outer_vertex[0] );
313 xglColor4fv( middle_color[0] );
314 xglVertex3fv( middle_vertex[0] );
322 /* Revision 1.9 1997/12/30 13:06:57 curt
323 /* A couple lighting tweaks ...
325 * Revision 1.8 1997/12/23 04:58:38 curt
326 * Tweaked the sky coloring a bit to build in structures to allow finer rgb
329 * Revision 1.7 1997/12/22 23:45:48 curt
330 * First stab at sunset/sunrise sky glow effects.
332 * Revision 1.6 1997/12/22 04:14:34 curt
333 * Aligned sky with sun so dusk/dawn effects can be correct relative to the sun.
335 * Revision 1.5 1997/12/19 23:34:59 curt
336 * Lot's of tweaking with sky rendering and lighting.
338 * Revision 1.4 1997/12/19 16:45:02 curt
339 * Working on scene rendering order and options.
341 * Revision 1.3 1997/12/18 23:32:36 curt
342 * First stab at sky dome actually starting to look reasonable. :-)
344 * Revision 1.2 1997/12/18 04:07:03 curt
345 * Worked on properly translating and positioning the sky dome.
347 * Revision 1.1 1997/12/17 23:14:30 curt
349 * Begin work on rendering the sky. (Rather than just using a clear screen.)