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_red_param, outer_red_amt, outer_red_diff;
107 float middle_red_param, middle_red_amt, middle_red_diff;
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_red_param = (10.0 - fabs(90.0 - sun_angle)) / 25.0;
121 outer_red_diff = outer_red_param / 6.0;
123 outer_red_param = 0.0;
124 outer_red_diff = 0.0;
126 printf(" outer_red_param = %.2f outer_red_diff = %.2f\n",
127 outer_red_param, outer_red_diff);
129 if ( (sun_angle > 85.0) && (sun_angle < 95.0) ) {
131 middle_red_param = (5.0 - fabs(90.0 - sun_angle)) / 12.5;
132 middle_red_diff = middle_red_param / 6.0;
134 middle_red_param = 0.0;
135 middle_red_diff = 0.0;
137 printf(" middle_red_param = %.2f middle_red_diff = %.2f\n",
138 middle_red_param, middle_red_diff);
140 /* calculate transition colors between sky and fog */
141 outer_red_amt = outer_red_param;
142 middle_red_amt = middle_red_param;
144 for ( i = 0; i < 6; i++ ) {
145 for ( j = 0; j < 3; j++ ) {
146 diff = l->sky_color[j] - l->fog_color[j];
147 inner_color[i][j] = l->sky_color[j] - diff * 0.3;
148 middle_color[i][j] = l->sky_color[j] - diff * 0.9;
149 outer_color[i][j] = l->fog_color[j];
151 outer_color[i][0] += outer_red_amt;
152 middle_color[i][0] += middle_red_amt;
153 if ( outer_color[i][0] > 1.0 ) { outer_color[i][0] = 1.0; }
154 if ( middle_color[i][0] > 1.0 ) { middle_color[i][0] = 1.0; }
155 inner_color[i][3] = middle_color[i][3] = outer_color[i][3] =
158 outer_red_amt -= outer_red_diff;
159 middle_red_amt -= middle_red_diff;
161 printf("inner_color[%d] = %.2f %.2f %.2f %.2f\n", i, inner_color[i][0],
162 inner_color[i][1], inner_color[i][2], inner_color[i][3]);
163 printf("middle_color[%d] = %.2f %.2f %.2f %.2f\n", i,
164 middle_color[i][0], middle_color[i][1], middle_color[i][2],
166 printf("outer_color[%d] = %.2f %.2f %.2f %.2f\n", i,
167 outer_color[i][0], outer_color[i][1], outer_color[i][2],
172 middle_red_amt = 0.0;
174 for ( i = 6; i < 12; i++ ) {
176 for ( j = 0; j < 3; j++ ) {
177 diff = l->sky_color[j] - l->fog_color[j];
178 inner_color[i][j] = l->sky_color[j] - diff * 0.3;
179 middle_color[i][j] = l->sky_color[j] - diff * 0.9;
180 outer_color[i][j] = l->fog_color[j];
182 outer_color[i][0] += outer_red_amt;
183 middle_color[i][0] += middle_red_amt;
184 if ( outer_color[i][0] > 1.0 ) { outer_color[i][0] = 1.0; }
185 if ( middle_color[i][0] > 1.0 ) { middle_color[i][0] = 1.0; }
186 inner_color[i][3] = middle_color[i][3] = outer_color[i][3] =
189 outer_red_amt += outer_red_diff;
190 middle_red_amt += middle_red_diff;
192 printf("inner_color[%d] = %.2f %.2f %.2f %.2f\n", i, inner_color[i][0],
193 inner_color[i][1], inner_color[i][2], inner_color[i][3]);
194 printf("middle_color[%d] = %.2f %.2f %.2f %.2f\n", i,
195 middle_color[i][0], middle_color[i][1], middle_color[i][2],
197 printf("outer_color[%d] = %.2f %.2f %.2f %.2f\n", i,
198 outer_color[i][0], outer_color[i][1], outer_color[i][2],
204 /* Initialize the sky structure and colors */
216 float /* inner_color[4], middle_color[4], diff, */ east_dot, dot, angle;
219 f = ¤t_aircraft.flight;
220 l = &cur_light_params;
223 printf("Rendering the sky.\n");
227 /* calculate the angle between v->surface_to_sun and
228 * v->surface_east. We do this so we can sort out the acos()
229 * ambiguity. I wish I could think of a more efficient way ... :-( */
230 east_dot = MAT3_DOT_PRODUCT(v->surface_to_sun, v->surface_east);
231 printf(" East dot product = %.2f\n", east_dot);
233 /* calculate the angle between v->surface_to_sun and
234 * v->surface_south. this is how much we have to rotate the sky
235 * for it to align with the sun */
236 dot = MAT3_DOT_PRODUCT(v->surface_to_sun, v->surface_south);
237 printf(" Dot product = %.2f\n", dot);
238 if ( east_dot >= 0 ) {
243 printf(" Sky needs to rotate = %.3f rads = %.1f degrees.\n",
244 angle, angle * RAD_TO_DEG);
246 /* Translate to view position */
247 xglTranslatef( v->cur_zero_elev.x, v->cur_zero_elev.y, v->cur_zero_elev.z );
248 /* printf(" Translated to %.2f %.2f %.2f\n",
249 v->cur_zero_elev.x, v->cur_zero_elev.y, v->cur_zero_elev.z ); */
251 /* Rotate to proper orientation */
252 printf(" lon = %.2f lat = %.2f\n", FG_Longitude * RAD_TO_DEG,
253 FG_Latitude * RAD_TO_DEG);
254 xglRotatef( FG_Longitude * RAD_TO_DEG, 0.0, 0.0, 1.0 );
255 xglRotatef( 90.0 - FG_Latitude * RAD_TO_DEG, 0.0, 1.0, 0.0 );
256 xglRotatef( angle * RAD_TO_DEG, 0.0, 0.0, 1.0 );
258 /* Draw inner/center section of sky*/
259 xglBegin( GL_TRIANGLE_FAN );
260 xglColor4fv(l->sky_color);
261 xglVertex3f(0.0, 0.0, CENTER_ELEV);
262 for ( i = 0; i < 12; i++ ) {
263 xglColor4fv( inner_color[i] );
264 xglVertex3fv( inner_vertex[i] );
266 xglColor4fv( inner_color[0] );
267 xglVertex3fv( inner_vertex[0] );
270 /* Draw the middle ring */
271 xglBegin( GL_TRIANGLE_STRIP );
272 for ( i = 0; i < 12; i++ ) {
273 xglColor4fv( middle_color[i] );
274 xglVertex3fv( middle_vertex[i] );
275 xglColor4fv( inner_color[i] );
276 xglVertex3fv( inner_vertex[i] );
278 xglColor4fv( middle_color[0] );
279 /* xglColor4f(1.0, 0.0, 0.0, 1.0); */
280 xglVertex3fv( middle_vertex[0] );
281 xglColor4fv( inner_color[0] );
282 /* xglColor4f(1.0, 0.0, 0.0, 1.0); */
283 xglVertex3fv( inner_vertex[0] );
286 /* Draw the outer ring */
287 xglBegin( GL_TRIANGLE_STRIP );
288 for ( i = 0; i < 12; i++ ) {
289 xglColor4fv( outer_color[i] );
290 xglVertex3fv( outer_vertex[i] );
291 xglColor4fv( middle_color[i] );
292 xglVertex3fv( middle_vertex[i] );
294 xglColor4fv( outer_color[0] );
295 xglVertex3fv( outer_vertex[0] );
296 xglColor4fv( middle_color[0] );
297 xglVertex3fv( middle_vertex[0] );
305 /* Revision 1.7 1997/12/22 23:45:48 curt
306 /* First stab at sunset/sunrise sky glow effects.
308 * Revision 1.6 1997/12/22 04:14:34 curt
309 * Aligned sky with sun so dusk/dawn effects can be correct relative to the sun.
311 * Revision 1.5 1997/12/19 23:34:59 curt
312 * Lot's of tweaking with sky rendering and lighting.
314 * Revision 1.4 1997/12/19 16:45:02 curt
315 * Working on scene rendering order and options.
317 * Revision 1.3 1997/12/18 23:32:36 curt
318 * First stab at sky dome actually starting to look reasonable. :-)
320 * Revision 1.2 1997/12/18 04:07:03 curt
321 * Worked on properly translating and positioning the sky dome.
323 * Revision 1.1 1997/12/17 23:14:30 curt
325 * Begin work on rendering the sky. (Rather than just using a clear screen.)