+/**************************************************************************
+ * sky.c -- model sky with an upside down "bowl"
+ *
+ * Written by Curtis Olson, started December 1997.
+ *
+ * Copyright (C) 1997 Curtis L. Olson - curt@infoplane.com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ * $Id$
+ * (Log is kept at end of this file)
+ **************************************************************************/
+
+
+#include <config.h>
+
+#ifdef HAVE_WINDOWS_H
+# include <windows.h>
+#endif
+
+#include <math.h>
+
+#include <GL/glut.h>
+#include <XGL/xgl.h>
+
+#include <Aircraft/aircraft.h>
+#include <Flight/flight.h>
+#include <Include/fg_constants.h>
+#include <Main/views.hxx>
+#include <Math/fg_random.h>
+#include <Time/event.h>
+#include <Time/fg_time.h>
+
+#include "sky.hxx"
+
+
+/*
+#include <Include/general.h>
+*/
+
+/* in meters of course */
+#define CENTER_ELEV 25000.0
+
+#define INNER_RADIUS 50000.0
+#define INNER_ELEV 20000.0
+
+#define MIDDLE_RADIUS 70000.0
+#define MIDDLE_ELEV 8000.0
+
+#define OUTER_RADIUS 80000.0
+#define OUTER_ELEV 0.0
+
+#define BOTTOM_RADIUS 50000.0
+#define BOTTOM_ELEV -2000.0
+
+
+static float inner_vertex[12][3];
+static float middle_vertex[12][3];
+static float outer_vertex[12][3];
+static float bottom_vertex[12][3];
+
+static float inner_color[12][4];
+static float middle_color[12][4];
+static float outer_color[12][4];
+
+
+/* Calculate the sky structure vertices */
+void fgSkyVerticesInit( void ) {
+ float theta;
+ int i;
+
+ printf(" Generating the sky dome vertices.\n");
+
+ for ( i = 0; i < 12; i++ ) {
+ theta = (i * 30.0) * DEG_TO_RAD;
+
+ inner_vertex[i][0] = cos(theta) * INNER_RADIUS;
+ inner_vertex[i][1] = sin(theta) * INNER_RADIUS;
+ inner_vertex[i][2] = INNER_ELEV;
+
+ /* printf(" %.2f %.2f\n", cos(theta) * INNER_RADIUS,
+ sin(theta) * INNER_RADIUS); */
+
+ middle_vertex[i][0] = cos((double)theta) * MIDDLE_RADIUS;
+ middle_vertex[i][1] = sin((double)theta) * MIDDLE_RADIUS;
+ middle_vertex[i][2] = MIDDLE_ELEV;
+
+ outer_vertex[i][0] = cos((double)theta) * OUTER_RADIUS;
+ outer_vertex[i][1] = sin((double)theta) * OUTER_RADIUS;
+ outer_vertex[i][2] = OUTER_ELEV;
+
+ bottom_vertex[i][0] = cos((double)theta) * BOTTOM_RADIUS;
+ bottom_vertex[i][1] = sin((double)theta) * BOTTOM_RADIUS;
+ bottom_vertex[i][2] = BOTTOM_ELEV;
+ }
+}
+
+
+/* (Re)calculate the sky colors at each vertex */
+void fgSkyColorsInit( void ) {
+ struct fgLIGHT *l;
+ float sun_angle, diff;
+ float outer_param[3], outer_amt[3], outer_diff[3];
+ float middle_param[3], middle_amt[3], middle_diff[3];
+ int i, j;
+
+ l = &cur_light_params;
+
+ printf(" Generating the sky colors for each vertex.\n");
+
+ /* setup for the possibility of sunset effects */
+ sun_angle = l->sun_angle * RAD_TO_DEG;
+ printf(" Sun angle in degrees = %.2f\n", sun_angle);
+
+ if ( (sun_angle > 80.0) && (sun_angle < 100.0) ) {
+ /* 0.0 - 0.4 */
+ outer_param[0] = (10.0 - fabs(90.0 - sun_angle)) / 25.0;
+ outer_param[1] = (10.0 - fabs(90.0 - sun_angle)) / 35.0;
+ outer_param[2] = 0.0;
+
+ middle_param[0] = (10.0 - fabs(90.0 - sun_angle)) / 20.0;
+ middle_param[1] = (10.0 - fabs(90.0 - sun_angle)) / 40.0;
+ middle_param[2] = 0.0;
+
+ outer_diff[0] = outer_param[0] / 6.0;
+ outer_diff[1] = outer_param[1] / 6.0;
+ outer_diff[2] = outer_param[2] / 6.0;
+
+ middle_diff[0] = middle_param[0] / 6.0;
+ middle_diff[1] = middle_param[1] / 6.0;
+ middle_diff[2] = middle_param[2] / 6.0;
+ } else {
+ outer_param[0] = outer_param[1] = outer_param[2] = 0.0;
+ middle_param[0] = middle_param[1] = middle_param[2] = 0.0;
+
+ outer_diff[0] = outer_diff[1] = outer_diff[2] = 0.0;
+ middle_diff[0] = middle_diff[1] = middle_diff[2] = 0.0;
+ }
+ /* printf(" outer_red_param = %.2f outer_red_diff = %.2f\n",
+ outer_red_param, outer_red_diff); */
+
+ /* calculate transition colors between sky and fog */
+ for ( j = 0; j < 3; j++ ) {
+ outer_amt[j] = outer_param[j];
+ middle_amt[j] = middle_param[j];
+ }
+
+ for ( i = 0; i < 6; i++ ) {
+ for ( j = 0; j < 3; j++ ) {
+ diff = l->sky_color[j] - l->fog_color[j];
+
+ inner_color[i][j] = l->sky_color[j] - diff * 0.3;
+ middle_color[i][j] = l->sky_color[j] - diff * 0.9 + middle_amt[j];
+ outer_color[i][j] = l->fog_color[j] + outer_amt[j];
+
+ if ( middle_color[i][j] > 1.00 ) { middle_color[i][j] = 1.00; }
+ if ( middle_color[i][j] < 0.10 ) { middle_color[i][j] = 0.10; }
+ if ( outer_color[i][j] > 1.00 ) { outer_color[i][j] = 1.00; }
+ if ( outer_color[i][j] < 0.10 ) { outer_color[i][j] = 0.10; }
+ }
+ inner_color[i][3] = middle_color[i][3] = outer_color[i][3] =
+ l->sky_color[3];
+
+ for ( j = 0; j < 3; j++ ) {
+ outer_amt[j] -= outer_diff[j];
+ middle_amt[j] -= middle_diff[j];
+ }
+
+ /*
+ printf("inner_color[%d] = %.2f %.2f %.2f %.2f\n", i, inner_color[i][0],
+ inner_color[i][1], inner_color[i][2], inner_color[i][3]);
+ printf("middle_color[%d] = %.2f %.2f %.2f %.2f\n", i,
+ middle_color[i][0], middle_color[i][1], middle_color[i][2],
+ middle_color[i][3]);
+ printf("outer_color[%d] = %.2f %.2f %.2f %.2f\n", i,
+ outer_color[i][0], outer_color[i][1], outer_color[i][2],
+ outer_color[i][3]);
+ */
+ }
+
+ for ( j = 0; j < 3; j++ ) {
+ outer_amt[j] = 0.0;
+ middle_amt[j] = 0.0;
+ }
+
+ for ( i = 6; i < 12; i++ ) {
+
+ for ( j = 0; j < 3; j++ ) {
+ diff = l->sky_color[j] - l->fog_color[j];
+
+ inner_color[i][j] = l->sky_color[j] - diff * 0.3;
+ middle_color[i][j] = l->sky_color[j] - diff * 0.9 + middle_amt[j];
+ outer_color[i][j] = l->fog_color[j] + outer_amt[j];
+
+ if ( middle_color[i][j] > 1.00 ) { middle_color[i][j] = 1.00; }
+ if ( middle_color[i][j] < 0.10 ) { middle_color[i][j] = 0.10; }
+ if ( outer_color[i][j] > 1.00 ) { outer_color[i][j] = 1.00; }
+ if ( outer_color[i][j] < 0.15 ) { outer_color[i][j] = 0.15; }
+ }
+ inner_color[i][3] = middle_color[i][3] = outer_color[i][3] =
+ l->sky_color[3];
+
+ for ( j = 0; j < 3; j++ ) {
+ outer_amt[j] += outer_diff[j];
+ middle_amt[j] += middle_diff[j];
+ }
+
+ /*
+ printf("inner_color[%d] = %.2f %.2f %.2f %.2f\n", i, inner_color[i][0],
+ inner_color[i][1], inner_color[i][2], inner_color[i][3]);
+ printf("middle_color[%d] = %.2f %.2f %.2f %.2f\n", i,
+ middle_color[i][0], middle_color[i][1], middle_color[i][2],
+ middle_color[i][3]);
+ printf("outer_color[%d] = %.2f %.2f %.2f %.2f\n", i,
+ outer_color[i][0], outer_color[i][1], outer_color[i][2],
+ outer_color[i][3]);
+ */
+ }
+}
+
+
+/* Initialize the sky structure and colors */
+void fgSkyInit( void ) {
+ printf("Initializing the sky\n");
+
+ fgSkyVerticesInit();
+
+ /* regester fgSkyColorsInit() as an event to be run periodically */
+ fgEventRegister("fgSkyColorsInit()", fgSkyColorsInit,
+ FG_EVENT_READY, 30000);
+}
+
+
+/* Draw the Sky */
+void fgSkyRender( void ) {
+ fgFLIGHT *f;
+ struct fgLIGHT *l;
+ struct fgVIEW *v;
+ float /* inner_color[4], middle_color[4], diff, */ east_dot, dot, angle;
+ int i;
+
+ f = current_aircraft.flight;
+ l = &cur_light_params;
+ v = ¤t_view;
+
+ /* printf("Rendering the sky.\n"); */
+
+ xglPushMatrix();
+
+ /* calculate the angle between v->surface_to_sun and
+ * v->surface_east. We do this so we can sort out the acos()
+ * ambiguity. I wish I could think of a more efficient way ... :-( */
+ east_dot = MAT3_DOT_PRODUCT(v->surface_to_sun, v->surface_east);
+ /* printf(" East dot product = %.2f\n", east_dot); */
+
+ /* calculate the angle between v->surface_to_sun and
+ * v->surface_south. this is how much we have to rotate the sky
+ * for it to align with the sun */
+ dot = MAT3_DOT_PRODUCT(v->surface_to_sun, v->surface_south);
+ /* printf(" Dot product = %.2f\n", dot); */
+ if ( east_dot >= 0 ) {
+ angle = acos(dot);
+ } else {
+ angle = -acos(dot);
+ }
+ /*printf(" Sky needs to rotate = %.3f rads = %.1f degrees.\n",
+ angle, angle * RAD_TO_DEG); */
+
+ /* Translate to view position */
+ xglTranslatef( v->cur_zero_elev.x, v->cur_zero_elev.y, v->cur_zero_elev.z );
+ /* printf(" Translated to %.2f %.2f %.2f\n",
+ v->cur_zero_elev.x, v->cur_zero_elev.y, v->cur_zero_elev.z ); */
+
+ /* Rotate to proper orientation */
+ /* printf(" lon = %.2f lat = %.2f\n", FG_Longitude * RAD_TO_DEG,
+ FG_Latitude * RAD_TO_DEG); */
+ xglRotatef( FG_Longitude * RAD_TO_DEG, 0.0, 0.0, 1.0 );
+ xglRotatef( 90.0 - FG_Latitude * RAD_TO_DEG, 0.0, 1.0, 0.0 );
+ xglRotatef( angle * RAD_TO_DEG, 0.0, 0.0, 1.0 );
+
+ /* Draw inner/center section of sky*/
+ xglBegin( GL_TRIANGLE_FAN );
+ xglColor4fv(l->sky_color);
+ xglVertex3f(0.0, 0.0, CENTER_ELEV);
+ for ( i = 0; i < 12; i++ ) {
+ xglColor4fv( inner_color[i] );
+ xglVertex3fv( inner_vertex[i] );
+ }
+ xglColor4fv( inner_color[0] );
+ xglVertex3fv( inner_vertex[0] );
+ xglEnd();
+
+ /* Draw the middle ring */
+ xglBegin( GL_TRIANGLE_STRIP );
+ for ( i = 0; i < 12; i++ ) {
+ xglColor4fv( middle_color[i] );
+ xglVertex3fv( middle_vertex[i] );
+ xglColor4fv( inner_color[i] );
+ xglVertex3fv( inner_vertex[i] );
+ }
+ xglColor4fv( middle_color[0] );
+ /* xglColor4f(1.0, 0.0, 0.0, 1.0); */
+ xglVertex3fv( middle_vertex[0] );
+ xglColor4fv( inner_color[0] );
+ /* xglColor4f(1.0, 0.0, 0.0, 1.0); */
+ xglVertex3fv( inner_vertex[0] );
+ xglEnd();
+
+ /* Draw the outer ring */
+ xglBegin( GL_TRIANGLE_STRIP );
+ for ( i = 0; i < 12; i++ ) {
+ xglColor4fv( outer_color[i] );
+ xglVertex3fv( outer_vertex[i] );
+ xglColor4fv( middle_color[i] );
+ xglVertex3fv( middle_vertex[i] );
+ }
+ xglColor4fv( outer_color[0] );
+ xglVertex3fv( outer_vertex[0] );
+ xglColor4fv( middle_color[0] );
+ xglVertex3fv( middle_vertex[0] );
+ xglEnd();
+
+ /* Draw the bottom skirt */
+ xglBegin( GL_TRIANGLE_STRIP );
+ for ( i = 0; i < 12; i++ ) {
+ xglColor4fv( l->fog_color );
+ xglVertex3fv( bottom_vertex[i] );
+ xglColor4fv( outer_color[i] );
+ xglVertex3fv( outer_vertex[i] );
+ }
+ xglColor4fv( l->fog_color );
+ xglVertex3fv( bottom_vertex[0] );
+ xglColor4fv( outer_color[0] );
+ xglVertex3fv( outer_vertex[0] );
+ xglEnd();
+
+ xglPopMatrix();
+}
+
+
+/* $Log$
+/* Revision 1.1 1998/04/22 13:21:32 curt
+/* C++ - ifing the code a bit.
+/*
+ * Revision 1.9 1998/04/03 21:52:50 curt
+ * Converting to Gnu autoconf system.
+ *
+ * Revision 1.8 1998/03/09 22:47:25 curt
+ * Incorporated Durk's updates.
+ *
+ * Revision 1.7 1998/02/19 13:05:49 curt
+ * Incorporated some HUD tweaks from Michelle America.
+ * Tweaked the sky's sunset/rise colors.
+ * Other misc. tweaks.
+ *
+ * Revision 1.6 1998/02/07 15:29:32 curt
+ * Incorporated HUD changes and struct/typedef changes from Charlie Hotchkiss
+ * <chotchkiss@namg.us.anritsu.com>
+ *
+ * Revision 1.5 1998/01/27 00:47:48 curt
+ * Incorporated Paul Bleisch's <bleisch@chromatic.com> new debug message
+ * system and commandline/config file processing code.
+ *
+ * Revision 1.4 1998/01/26 15:54:28 curt
+ * Added a "skirt" to try to help hide gaps between scenery and sky. This will
+ * have to be revisited in the future.
+ *
+ * Revision 1.3 1998/01/19 19:26:59 curt
+ * Merged in make system changes from Bob Kuehne <rpk@sgi.com>
+ * This should simplify things tremendously.
+ *
+ * Revision 1.2 1998/01/19 18:40:17 curt
+ * Tons of little changes to clean up the code and to remove fatal errors
+ * when building with the c++ compiler.
+ *
+ * Revision 1.1 1998/01/07 03:16:19 curt
+ * Moved from .../Src/Scenery/ to .../Src/Astro/
+ *
+ * Revision 1.11 1997/12/30 22:22:38 curt
+ * Further integration of event manager.
+ *
+ * Revision 1.10 1997/12/30 20:47:53 curt
+ * Integrated new event manager with subsystem initializations.
+ *
+ * Revision 1.9 1997/12/30 13:06:57 curt
+ * A couple lighting tweaks ...
+ *
+ * Revision 1.8 1997/12/23 04:58:38 curt
+ * Tweaked the sky coloring a bit to build in structures to allow finer rgb
+ * control.
+ *
+ * Revision 1.7 1997/12/22 23:45:48 curt
+ * First stab at sunset/sunrise sky glow effects.
+ *
+ * Revision 1.6 1997/12/22 04:14:34 curt
+ * Aligned sky with sun so dusk/dawn effects can be correct relative to the sun.
+ *
+ * Revision 1.5 1997/12/19 23:34:59 curt
+ * Lot's of tweaking with sky rendering and lighting.
+ *
+ * Revision 1.4 1997/12/19 16:45:02 curt
+ * Working on scene rendering order and options.
+ *
+ * Revision 1.3 1997/12/18 23:32:36 curt
+ * First stab at sky dome actually starting to look reasonable. :-)
+ *
+ * Revision 1.2 1997/12/18 04:07:03 curt
+ * Worked on properly translating and positioning the sky dome.
+ *
+ * Revision 1.1 1997/12/17 23:14:30 curt
+ * Initial revision.
+ * Begin work on rendering the sky. (Rather than just using a clear screen.)
+ *
+ */