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] > 1.0 ) { middle_color[i][j] = 1.0; }
160 if ( outer_color[i][j] > 1.0 ) { outer_color[i][j] = 1.0; }
162 inner_color[i][3] = middle_color[i][3] = outer_color[i][3] =
165 for ( j = 0; j < 3; j++ ) {
166 outer_amt[j] -= outer_diff[j];
167 middle_amt[j] -= middle_diff[j];
170 printf("inner_color[%d] = %.2f %.2f %.2f %.2f\n", i, inner_color[i][0],
171 inner_color[i][1], inner_color[i][2], inner_color[i][3]);
172 printf("middle_color[%d] = %.2f %.2f %.2f %.2f\n", i,
173 middle_color[i][0], middle_color[i][1], middle_color[i][2],
175 printf("outer_color[%d] = %.2f %.2f %.2f %.2f\n", i,
176 outer_color[i][0], outer_color[i][1], outer_color[i][2],
180 for ( j = 0; j < 3; j++ ) {
185 for ( i = 6; i < 12; i++ ) {
187 for ( j = 0; j < 3; j++ ) {
188 diff = l->sky_color[j] - l->fog_color[j];
190 inner_color[i][j] = l->sky_color[j] - diff * 0.3;
191 middle_color[i][j] = l->sky_color[j] - diff * 0.9 + middle_amt[j];
192 outer_color[i][j] = l->fog_color[j] + outer_amt[j];
194 if ( middle_color[i][j] > 1.0 ) { middle_color[i][j] = 1.0; }
195 if ( outer_color[i][j] > 1.0 ) { outer_color[i][j] = 1.0; }
197 inner_color[i][3] = middle_color[i][3] = outer_color[i][3] =
200 for ( j = 0; j < 3; j++ ) {
201 outer_amt[j] += outer_diff[j];
202 middle_amt[j] += middle_diff[j];
205 printf("inner_color[%d] = %.2f %.2f %.2f %.2f\n", i, inner_color[i][0],
206 inner_color[i][1], inner_color[i][2], inner_color[i][3]);
207 printf("middle_color[%d] = %.2f %.2f %.2f %.2f\n", i,
208 middle_color[i][0], middle_color[i][1], middle_color[i][2],
210 printf("outer_color[%d] = %.2f %.2f %.2f %.2f\n", i,
211 outer_color[i][0], outer_color[i][1], outer_color[i][2],
217 /* Initialize the sky structure and colors */
229 float /* inner_color[4], middle_color[4], diff, */ east_dot, dot, angle;
232 f = ¤t_aircraft.flight;
233 l = &cur_light_params;
236 printf("Rendering the sky.\n");
240 /* calculate the angle between v->surface_to_sun and
241 * v->surface_east. We do this so we can sort out the acos()
242 * ambiguity. I wish I could think of a more efficient way ... :-( */
243 east_dot = MAT3_DOT_PRODUCT(v->surface_to_sun, v->surface_east);
244 printf(" East dot product = %.2f\n", east_dot);
246 /* calculate the angle between v->surface_to_sun and
247 * v->surface_south. this is how much we have to rotate the sky
248 * for it to align with the sun */
249 dot = MAT3_DOT_PRODUCT(v->surface_to_sun, v->surface_south);
250 printf(" Dot product = %.2f\n", dot);
251 if ( east_dot >= 0 ) {
256 printf(" Sky needs to rotate = %.3f rads = %.1f degrees.\n",
257 angle, angle * RAD_TO_DEG);
259 /* Translate to view position */
260 xglTranslatef( v->cur_zero_elev.x, v->cur_zero_elev.y, v->cur_zero_elev.z );
261 /* printf(" Translated to %.2f %.2f %.2f\n",
262 v->cur_zero_elev.x, v->cur_zero_elev.y, v->cur_zero_elev.z ); */
264 /* Rotate to proper orientation */
265 printf(" lon = %.2f lat = %.2f\n", FG_Longitude * RAD_TO_DEG,
266 FG_Latitude * RAD_TO_DEG);
267 xglRotatef( FG_Longitude * RAD_TO_DEG, 0.0, 0.0, 1.0 );
268 xglRotatef( 90.0 - FG_Latitude * RAD_TO_DEG, 0.0, 1.0, 0.0 );
269 xglRotatef( angle * RAD_TO_DEG, 0.0, 0.0, 1.0 );
271 /* Draw inner/center section of sky*/
272 xglBegin( GL_TRIANGLE_FAN );
273 xglColor4fv(l->sky_color);
274 xglVertex3f(0.0, 0.0, CENTER_ELEV);
275 for ( i = 0; i < 12; i++ ) {
276 xglColor4fv( inner_color[i] );
277 xglVertex3fv( inner_vertex[i] );
279 xglColor4fv( inner_color[0] );
280 xglVertex3fv( inner_vertex[0] );
283 /* Draw the middle ring */
284 xglBegin( GL_TRIANGLE_STRIP );
285 for ( i = 0; i < 12; i++ ) {
286 xglColor4fv( middle_color[i] );
287 xglVertex3fv( middle_vertex[i] );
288 xglColor4fv( inner_color[i] );
289 xglVertex3fv( inner_vertex[i] );
291 xglColor4fv( middle_color[0] );
292 /* xglColor4f(1.0, 0.0, 0.0, 1.0); */
293 xglVertex3fv( middle_vertex[0] );
294 xglColor4fv( inner_color[0] );
295 /* xglColor4f(1.0, 0.0, 0.0, 1.0); */
296 xglVertex3fv( inner_vertex[0] );
299 /* Draw the outer ring */
300 xglBegin( GL_TRIANGLE_STRIP );
301 for ( i = 0; i < 12; i++ ) {
302 xglColor4fv( outer_color[i] );
303 xglVertex3fv( outer_vertex[i] );
304 xglColor4fv( middle_color[i] );
305 xglVertex3fv( middle_vertex[i] );
307 xglColor4fv( outer_color[0] );
308 xglVertex3fv( outer_vertex[0] );
309 xglColor4fv( middle_color[0] );
310 xglVertex3fv( middle_vertex[0] );
318 /* Revision 1.8 1997/12/23 04:58:38 curt
319 /* Tweaked the sky coloring a bit to build in structures to allow finer rgb
322 * Revision 1.7 1997/12/22 23:45:48 curt
323 * First stab at sunset/sunrise sky glow effects.
325 * Revision 1.6 1997/12/22 04:14:34 curt
326 * Aligned sky with sun so dusk/dawn effects can be correct relative to the sun.
328 * Revision 1.5 1997/12/19 23:34:59 curt
329 * Lot's of tweaking with sky rendering and lighting.
331 * Revision 1.4 1997/12/19 16:45:02 curt
332 * Working on scene rendering order and options.
334 * Revision 1.3 1997/12/18 23:32:36 curt
335 * First stab at sky dome actually starting to look reasonable. :-)
337 * Revision 1.2 1997/12/18 04:07:03 curt
338 * Worked on properly translating and positioning the sky dome.
340 * Revision 1.1 1997/12/17 23:14:30 curt
342 * Begin work on rendering the sky. (Rather than just using a clear screen.)