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flightgear/Main/GLUTmain.c
1997-12-30 22:22:31 +00:00

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C

/**************************************************************************
* GLUTmain.c -- top level sim routines
*
* Written by Curtis Olson for OpenGL, started May 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)
**************************************************************************/
#ifdef WIN32
# include <windows.h>
#endif
#include <GL/glut.h>
#include "../XGL/xgl.h"
#include <stdio.h>
#include "GLUTkey.h"
#include "fg_init.h"
#include "views.h"
#include "../Include/constants.h"
#include "../Include/general.h"
#include "../Aircraft/aircraft.h"
#include "../Cockpit/cockpit.h"
#include "../Joystick/joystick.h"
#include "../Math/fg_geodesy.h"
#include "../Math/mat3.h"
#include "../Math/polar.h"
#include "../Scenery/mesh.h"
#include "../Scenery/moon.h"
#include "../Scenery/scenery.h"
#include "../Scenery/sky.h"
#include "../Scenery/stars.h"
#include "../Scenery/sun.h"
#include "../Time/event.h"
#include "../Time/fg_time.h"
#include "../Time/fg_timer.h"
#include "../Time/sunpos.h"
#include "../Weather/weather.h"
/* This is a record containing global housekeeping information */
struct fgGENERAL general;
/* view parameters */
static GLfloat win_ratio = 1.0;
static GLint winWidth, winHeight;
/* temporary hack */
/* pointer to scenery structure */
/* static GLint scenery, runway; */
double Simtime;
/* Another hack */
int use_signals = 0;
/* Yet another hack. This one used by the HUD code. Michele */
int show_hud;
/* Yet another other hack. Used for my prototype instrument code. (Durk) */
int displayInstruments;
/**************************************************************************
* fgInitVisuals() -- Initialize various GL/view parameters
**************************************************************************/
static void fgInitVisuals() {
struct fgLIGHT *l;
struct fgTIME *t;
struct fgWEATHER *w;
l = &cur_light_params;
t = &cur_time_params;
w = &current_weather;
/* xglDisable( GL_DITHER ); */
/* If enabled, normal vectors specified with glNormal are scaled
to unit length after transformation. See glNormal. */
xglEnable( GL_NORMALIZE );
xglEnable( GL_LIGHTING );
xglEnable( GL_LIGHT0 );
xglLightfv( GL_LIGHT0, GL_POSITION, l->sun_vec );
xglFogi (GL_FOG_MODE, GL_LINEAR);
/* xglFogf (GL_FOG_START, 1.0); */
xglFogf (GL_FOG_END, w->visibility);
/* xglFogf (GL_FOG_DENSITY, w->visibility); */
xglHint (GL_FOG_HINT, GL_NICEST /* GL_FASTEST */ );
}
/**************************************************************************
* Update the view volume, position, and orientation
**************************************************************************/
static void fgUpdateViewParams() {
struct fgFLIGHT *f;
struct fgLIGHT *l;
struct fgTIME *t;
struct fgVIEW *v;
f = &current_aircraft.flight;
l = &cur_light_params;
t = &cur_time_params;
v = &current_view;
fgViewUpdate(f, v, l);
if (displayInstruments)
{
xglViewport(0, (GLint)(winHeight / 2 ) , (GLint)winWidth, (GLint)winHeight / 2);
/* Tell GL we are about to modify the projection parameters */
xglMatrixMode(GL_PROJECTION);
xglLoadIdentity();
gluPerspective(55.0, 2.0/win_ratio, 1.0, 100000.0);
}
else
{
xglViewport(0, 0 , (GLint)winWidth, (GLint) winHeight);
/* Tell GL we are about to modify the projection parameters */
xglMatrixMode(GL_PROJECTION);
xglLoadIdentity();
gluPerspective(55.0, 1.0/win_ratio, 1.0, 100000.0);
}
xglMatrixMode(GL_MODELVIEW);
xglLoadIdentity();
/* set up our view volume (default) */
gluLookAt(v->view_pos.x, v->view_pos.y, v->view_pos.z,
v->view_pos.x + v->view_forward[0],
v->view_pos.y + v->view_forward[1],
v->view_pos.z + v->view_forward[2],
v->view_up[0], v->view_up[1], v->view_up[2]);
/* lock view horizontally towards sun (testing) */
/* gluLookAt(v->view_pos.x, v->view_pos.y, v->view_pos.z,
v->view_pos.x + v->surface_to_sun[0],
v->view_pos.y + v->surface_to_sun[1],
v->view_pos.z + v->surface_to_sun[2],
v->view_up[0], v->view_up[1], v->view_up[2]); */
/* lock view horizontally towards south (testing) */
/* gluLookAt(v->view_pos.x, v->view_pos.y, v->view_pos.z,
v->view_pos.x + v->surface_south[0],
v->view_pos.y + v->surface_south[1],
v->view_pos.z + v->surface_south[2],
v->view_up[0], v->view_up[1], v->view_up[2]); */
/* set the sun position */
xglLightfv( GL_LIGHT0, GL_POSITION, l->sun_vec );
}
/*************************************************************************
* Draw a basic instrument panel
************************************************************************/
static void fgUpdateInstrViewParams() {
xglViewport(0, 0 , (GLint)winWidth, (GLint)winHeight / 2);
xglMatrixMode(GL_PROJECTION);
xglPushMatrix();
xglLoadIdentity();
gluOrtho2D(0, 640, 0, 480);
xglMatrixMode(GL_MODELVIEW);
xglPushMatrix();
xglLoadIdentity();
xglColor3f(1.0, 1.0, 1.0);
xglIndexi(7);
xglDisable(GL_DEPTH_TEST);
xglDisable(GL_LIGHTING);
xglLineWidth(1);
xglColor3f (0.5, 0.5, 0.5);
xglBegin(GL_QUADS);
xglVertex2f(0.0, 0.00);
xglVertex2f(0.0, 480.0);
xglVertex2f(640.0,480.0);
xglVertex2f(640.0, 0.0);
xglEnd();
xglRectf(0.0,0.0, 640, 480);
xglEnable(GL_DEPTH_TEST);
xglEnable(GL_LIGHTING);
xglMatrixMode(GL_PROJECTION);
xglPopMatrix();
xglMatrixMode(GL_MODELVIEW);
xglPopMatrix();
}
/**************************************************************************
* Update all Visuals (redraws anything graphics related)
**************************************************************************/
static void fgRenderFrame( void ) {
struct fgLIGHT *l;
struct fgTIME *t;
struct fgVIEW *v;
double angle;
GLfloat white[4] = { 1.0, 1.0, 1.0, 1.0 };
l = &cur_light_params;
t = &cur_time_params;
v = &current_view;
/* update view volume parameters */
fgUpdateViewParams();
xglClear( GL_DEPTH_BUFFER_BIT /* | GL_COLOR_BUFFER_BIT */ );
/* Tell GL we are switching to model view parameters */
xglMatrixMode(GL_MODELVIEW);
/* xglLoadIdentity(); */
/* draw sky */
xglDisable( GL_DEPTH_TEST );
xglDisable( GL_LIGHTING );
xglDisable( GL_CULL_FACE );
xglDisable( GL_FOG );
xglShadeModel( GL_SMOOTH );
fgSkyRender();
/* setup transformation for drawing astronomical objects */
xglPushMatrix();
/* Translate to view position */
xglTranslatef( v->view_pos.x, v->view_pos.y, v->view_pos.z );
/* Rotate based on gst (side real time) */
angle = t->gst * 15.041085; /* should be 15.041085, Curt thought it was 15*/
/* printf("Rotating astro objects by %.2f degrees\n",angle); */
xglRotatef( angle, 0.0, 0.0, -1.0 );
/* draw stars and planets */
fgStarsRender();
/* draw the sun */
fgSunRender();
/* render the moon */
xglEnable( GL_LIGHTING );
/* set lighting parameters */
xglLightfv(GL_LIGHT0, GL_AMBIENT, white );
xglLightfv(GL_LIGHT0, GL_DIFFUSE, white );
xglEnable( GL_CULL_FACE );
fgMoonRender();
xglPopMatrix();
/* draw scenery */
xglShadeModel( GL_SMOOTH );
xglEnable( GL_DEPTH_TEST );
xglEnable( GL_FOG );
xglFogfv (GL_FOG_COLOR, l->fog_color);
/* set lighting parameters */
xglLightfv(GL_LIGHT0, GL_AMBIENT, l->scene_ambient );
xglLightfv(GL_LIGHT0, GL_DIFFUSE, l->scene_diffuse );
fgSceneryRender();
/* display HUD */
if( show_hud ) {
fgCockpitUpdate();
}
/* display instruments */
if (displayInstruments) {
fgUpdateInstrViewParams();
}
#ifdef GLUT
xglutSwapBuffers();
#endif
}
/**************************************************************************
* Update internal time dependent calculations (i.e. flight model)
**************************************************************************/
void fgUpdateTimeDepCalcs(int multi_loop) {
struct fgFLIGHT *f;
struct fgTIME *t;
struct fgVIEW *v;
int i;
f = &current_aircraft.flight;
t = &cur_time_params;
v = &current_view;
/* update the flight model */
if ( multi_loop < 0 ) {
multi_loop = DEFAULT_MULTILOOP;
}
/* printf("updating flight model x %d\n", multi_loop); */
fgFlightModelUpdate(FG_LARCSIM, f, multi_loop);
/* update the view angle */
for ( i = 0; i < multi_loop; i++ ) {
if ( fabs(v->goal_view_offset - v->view_offset) < 0.05 ) {
v->view_offset = v->goal_view_offset;
break;
} else {
/* move v->view_offset towards v->goal_view_offset */
if ( v->goal_view_offset > v->view_offset ) {
if ( v->goal_view_offset - v->view_offset < FG_PI ) {
v->view_offset += 0.01;
} else {
v->view_offset -= 0.01;
}
} else {
if ( v->view_offset - v->goal_view_offset < FG_PI ) {
v->view_offset -= 0.01;
} else {
v->view_offset += 0.01;
}
}
if ( v->view_offset > FG_2PI ) {
v->view_offset -= FG_2PI;
} else if ( v->view_offset < 0 ) {
v->view_offset += FG_2PI;
}
}
}
}
void fgInitTimeDepCalcs() {
/* initialize timer */
#ifdef USE_ITIMER
fgTimerInit( 1.0 / DEFAULT_TIMER_HZ, fgUpdateTimeDepCalcs );
#endif USE_ITIMER
}
/**************************************************************************
* Scenery management routines
**************************************************************************/
/* static void fgSceneryInit_OLD() { */
/* make scenery */
/* scenery = fgSceneryCompile_OLD();
runway = fgRunwayHack_OLD(0.69, 53.07);
} */
/* create the scenery */
/* GLint fgSceneryCompile_OLD() {
GLint scenery;
scenery = mesh2GL(mesh_ptr_OLD);
return(scenery);
}
*/
/* hack in a runway */
/* GLint fgRunwayHack_OLD(double width, double length) {
static GLfloat concrete[4] = { 0.5, 0.5, 0.5, 1.0 };
static GLfloat line[4] = { 0.9, 0.9, 0.9, 1.0 };
int i;
int num_lines = 16;
float line_len, line_width_2, cur_pos;
runway = xglGenLists(1);
xglNewList(runway, GL_COMPILE);
*/
/* draw concrete */
/* xglBegin(GL_POLYGON);
xglMaterialfv( GL_FRONT, GL_AMBIENT_AND_DIFFUSE, concrete );
xglNormal3f(0.0, 0.0, 1.0);
xglVertex3d( 0.0, -width/2.0, 0.0);
xglVertex3d( 0.0, width/2.0, 0.0);
xglVertex3d(length, width/2.0, 0.0);
xglVertex3d(length, -width/2.0, 0.0);
xglEnd();
*/
/* draw center line */
/* xglMaterialfv( GL_FRONT, GL_AMBIENT_AND_DIFFUSE, line );
line_len = length / ( 2 * num_lines + 1);
printf("line_len = %.3f\n", line_len);
line_width_2 = 0.02;
cur_pos = line_len;
for ( i = 0; i < num_lines; i++ ) {
xglBegin(GL_POLYGON);
xglVertex3d( cur_pos, -line_width_2, 0.005);
xglVertex3d( cur_pos, line_width_2, 0.005);
cur_pos += line_len;
xglVertex3d( cur_pos, line_width_2, 0.005);
xglVertex3d( cur_pos, -line_width_2, 0.005);
cur_pos += line_len;
xglEnd();
}
xglEndList();
return(runway);
}
*/
/* draw the scenery */
/*static void fgSceneryDraw_OLD() {
static float z = 32.35;
xglPushMatrix();
xglCallList(scenery);
printf("*** Drawing runway at %.2f\n", z);
xglTranslatef( -398391.28, 120070.41, 32.35);
xglRotatef(170.0, 0.0, 0.0, 1.0);
xglCallList(runway);
xglPopMatrix();
}
*/
/* What should we do when we have nothing else to do? How about get
* ready for the next move and update the display? */
static void fgMainLoop( void ) {
static int remainder = 0;
int elapsed, multi_loop;
double cur_elev;
double joy_x, joy_y;
int joy_b1, joy_b2;
struct fgAIRCRAFT *a;
struct fgFLIGHT *f;
struct fgTIME *t;
printf("Running Main Loop\n");
printf("======= ==== ====\n");
a = &current_aircraft;
f = &a->flight;
t = &cur_time_params;
/* update "time" */
fgTimeUpdate(f, t);
/* Read joystick */
/* fgJoystickRead( &joy_x, &joy_y, &joy_b1, &joy_b2 );
printf( "Joystick X %f Y %f B1 %d B2 %d\n",
joy_x, joy_y, joy_b1, joy_b2 );
fgElevSet( -joy_y );
fgAileronSet( joy_x ); */
/* Calculate model iterations needed */
elapsed = fgGetTimeInterval();
printf("Time interval is = %d, previous remainder is = %d\n", elapsed,
remainder);
printf("--> Frame rate is = %.2f\n", 1000.0 / (float)elapsed);
elapsed += remainder;
multi_loop = ((float)elapsed * 0.001) * DEFAULT_MODEL_HZ;
remainder = elapsed - ((multi_loop*1000) / DEFAULT_MODEL_HZ);
printf("Model iterations needed = %d, new remainder = %d\n", multi_loop,
remainder);
/* Run flight model */
if ( ! use_signals ) {
/* flight model */
fgUpdateTimeDepCalcs(multi_loop);
}
/* I'm just sticking this here for now, it should probably move
* eventually */
cur_elev = mesh_altitude(FG_Longitude * RAD_TO_ARCSEC,
FG_Latitude * RAD_TO_ARCSEC);
/* printf("Ground elevation is %.2f meters here.\n", cur_elev); */
/* FG_Runway_altitude = cur_elev * METER_TO_FEET; */
if ( FG_Altitude * FEET_TO_METER < cur_elev + 3.758099) {
/* set this here, otherwise if we set runway height above our
current height we get a really nasty bounce. */
FG_Runway_altitude = FG_Altitude - 3.758099;
/* now set aircraft altitude above ground */
FG_Altitude = cur_elev * METER_TO_FEET + 3.758099;
printf("<*> resetting altitude to %.0f meters\n",
FG_Altitude * FEET_TO_METER);
}
/* fgAircraftOutputCurrent(a); */
/* Process/manage pending events */
fgEventProcess();
/* redraw display */
fgRenderFrame();
printf("\n");
}
/**************************************************************************
* Handle new window size or exposure
**************************************************************************/
static void fgReshape( int width, int height ) {
/* Do this so we can call fgReshape(0,0) ourselves without having to know
* what the values of width & height are. */
if ( (height > 0) && (width > 0) ) {
win_ratio = (GLfloat) height / (GLfloat) width;
}
winWidth = width;
winHeight = height;
/* Inform gl of our view window size (now handled elsewhere) */
/* xglViewport(0, 0, (GLint)width, (GLint)height); */
fgUpdateViewParams();
/* xglClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT ); */
}
/**************************************************************************
* Main ...
**************************************************************************/
int main( int argc, char *argv[] ) {
struct fgFLIGHT *f;
f = &current_aircraft.flight;
printf("Flight Gear: Version %s\n\n", VERSION);
/**********************************************************************
* Initialize the Window/Graphics environment.
**********************************************************************/
#ifdef GLUT
/* initialize GLUT */
xglutInit(&argc, argv);
/* Define Display Parameters */
xglutInitDisplayMode( GLUT_RGB | GLUT_DEPTH | GLUT_DOUBLE );
/* Define initial window size */
xglutInitWindowSize(640, 480);
/* Initialize windows */
xglutCreateWindow("Flight Gear");
#endif
/* This is the general house keeping init routine */
fgInitGeneral();
/* This is the top level init routine which calls all the other
* subsystem initialization routines. If you are adding a
* subsystem to flight gear, its initialization call should
* located in this routine.*/
fgInitSubsystems();
/* setup view parameters, only makes GL calls */
fgInitVisuals();
if ( use_signals ) {
/* init timer routines, signals, etc. Arrange for an alarm
signal to be generated, etc. */
fgInitTimeDepCalcs();
}
/**********************************************************************
* Initialize the Event Handlers.
**********************************************************************/
#ifdef GLUT
/* call fgReshape() on window resizes */
xglutReshapeFunc( fgReshape );
/* call key() on keyboard event */
xglutKeyboardFunc( GLUTkey );
glutSpecialFunc( GLUTspecialkey );
/* call fgMainLoop() whenever there is nothing else to do */
xglutIdleFunc( fgMainLoop );
/* draw the scene */
xglutDisplayFunc( fgRenderFrame );
/* pass control off to the GLUT event handler */
glutMainLoop();
#endif
return(0);
}
#ifdef NO_PRINTF
#include <stdarg.h>
int printf (const char *format, ...) {
}
#endif
/* $Log$
/* Revision 1.44 1997/12/30 22:22:31 curt
/* Further integration of event manager.
/*
* Revision 1.43 1997/12/30 20:47:43 curt
* Integrated new event manager with subsystem initializations.
*
* Revision 1.42 1997/12/30 16:36:47 curt
* Merged in Durk's changes ...
*
* Revision 1.41 1997/12/30 13:06:56 curt
* A couple lighting tweaks ...
*
* Revision 1.40 1997/12/30 01:38:37 curt
* Switched back to per vertex normals and smooth shading for terrain.
*
* Revision 1.39 1997/12/22 23:45:45 curt
* First stab at sunset/sunrise sky glow effects.
*
* Revision 1.38 1997/12/22 04:14:28 curt
* Aligned sky with sun so dusk/dawn effects can be correct relative to the sun.
*
* Revision 1.37 1997/12/19 23:34:03 curt
* Lot's of tweaking with sky rendering and lighting.
*
* Revision 1.36 1997/12/19 16:44:57 curt
* Working on scene rendering order and options.
*
* Revision 1.35 1997/12/18 23:32:32 curt
* First stab at sky dome actually starting to look reasonable. :-)
*
* Revision 1.34 1997/12/17 23:13:34 curt
* Began working on rendering a sky.
*
* Revision 1.33 1997/12/15 23:54:45 curt
* Add xgl wrappers for debugging.
* Generate terrain normals on the fly.
*
* Revision 1.32 1997/12/15 20:59:08 curt
* Misc. tweaks.
*
* Revision 1.31 1997/12/12 21:41:25 curt
* More light/material property tweaking ... still a ways off.
*
* Revision 1.30 1997/12/12 19:52:47 curt
* Working on lightling and material properties.
*
* Revision 1.29 1997/12/11 04:43:54 curt
* Fixed sun vector and lighting problems. I thing the moon is now lit
* correctly.
*
* Revision 1.28 1997/12/10 22:37:45 curt
* Prepended "fg" on the name of all global structures that didn't have it yet.
* i.e. "struct WEATHER {}" became "struct fgWEATHER {}"
*
* Revision 1.27 1997/12/09 05:11:54 curt
* Working on tweaking lighting.
*
* Revision 1.26 1997/12/09 04:25:29 curt
* Working on adding a global lighting params structure.
*
* Revision 1.25 1997/12/08 22:54:09 curt
* Enabled GL_CULL_FACE.
*
* Revision 1.24 1997/11/25 19:25:32 curt
* Changes to integrate Durk's moon/sun code updates + clean up.
*
* Revision 1.23 1997/11/15 18:16:34 curt
* minor tweaks.
*
* Revision 1.22 1997/10/30 12:38:41 curt
* Working on new scenery subsystem.
*
* Revision 1.21 1997/09/23 00:29:38 curt
* Tweaks to get things to compile with gcc-win32.
*
* Revision 1.20 1997/09/22 14:44:19 curt
* Continuing to try to align stars correctly.
*
* Revision 1.19 1997/09/18 16:20:08 curt
* At dusk/dawn add/remove stars in stages.
*
* Revision 1.18 1997/09/16 22:14:51 curt
* Tweaked time of day lighting equations. Don't draw stars during the day.
*
* Revision 1.17 1997/09/16 15:50:29 curt
* Working on star alignment and time issues.
*
* Revision 1.16 1997/09/13 02:00:06 curt
* Mostly working on stars and generating sidereal time for accurate star
* placement.
*
* Revision 1.15 1997/09/05 14:17:27 curt
* More tweaking with stars.
*
* Revision 1.14 1997/09/05 01:35:53 curt
* Working on getting stars right.
*
* Revision 1.13 1997/09/04 02:17:34 curt
* Shufflin' stuff.
*
* Revision 1.12 1997/08/27 21:32:24 curt
* Restructured view calculation code. Added stars.
*
* Revision 1.11 1997/08/27 03:30:16 curt
* Changed naming scheme of basic shared structures.
*
* Revision 1.10 1997/08/25 20:27:22 curt
* Merged in initial HUD and Joystick code.
*
* Revision 1.9 1997/08/22 21:34:39 curt
* Doing a bit of reorganizing and house cleaning.
*
* Revision 1.8 1997/08/19 23:55:03 curt
* Worked on better simulating real lighting.
*
* Revision 1.7 1997/08/16 12:22:38 curt
* Working on improving the lighting/shading.
*
* Revision 1.6 1997/08/13 20:24:56 curt
* Changes due to changing sunpos interface.
*
* Revision 1.5 1997/08/06 21:08:32 curt
* Sun position now *really* works (I think) ... I still have sun time warping
* code in place, probably should remove it soon.
*
* Revision 1.4 1997/08/06 15:41:26 curt
* Working on correct sun position.
*
* Revision 1.3 1997/08/06 00:24:22 curt
* Working on correct real time sun lighting.
*
* Revision 1.2 1997/08/04 20:25:15 curt
* Organizational tweaking.
*
* Revision 1.1 1997/08/02 18:45:00 curt
* Renamed GLmain.c GLUTmain.c
*
* Revision 1.43 1997/08/02 16:23:47 curt
* Misc. tweaks.
*
* Revision 1.42 1997/08/01 19:43:33 curt
* Making progress with coordinate system overhaul.
*
* Revision 1.41 1997/07/31 22:52:37 curt
* Working on redoing internal coordinate systems & scenery transformations.
*
* Revision 1.40 1997/07/30 16:12:42 curt
* Moved fg_random routines from Util/ to Math/
*
* Revision 1.39 1997/07/21 14:45:01 curt
* Minor tweaks.
*
* Revision 1.38 1997/07/19 23:04:47 curt
* Added an initial weather section.
*
* Revision 1.37 1997/07/19 22:34:02 curt
* Moved PI definitions to ../constants.h
* Moved random() stuff to ../Utils/ and renamed fg_random()
*
* Revision 1.36 1997/07/18 23:41:25 curt
* Tweaks for building with Cygnus Win32 compiler.
*
* Revision 1.35 1997/07/18 14:28:34 curt
* Hacked in some support for wind/turbulence.
*
* Revision 1.34 1997/07/16 20:04:48 curt
* Minor tweaks to aid Win32 port.
*
* Revision 1.33 1997/07/12 03:50:20 curt
* Added an #include <Windows32/Base.h> to help compiling for Win32
*
* Revision 1.32 1997/07/11 03:23:18 curt
* Solved some scenery display/orientation problems. Still have a positioning
* (or transformation?) problem.
*
* Revision 1.31 1997/07/11 01:29:58 curt
* More tweaking of terrian floor.
*
* Revision 1.30 1997/07/10 04:26:37 curt
* We now can interpolated ground elevation for any position in the grid. We
* can use this to enforce a "hard" ground. We still need to enforce some
* bounds checking so that we don't try to lookup data points outside the
* grid data set.
*
* Revision 1.29 1997/07/09 21:31:12 curt
* Working on making the ground "hard."
*
* Revision 1.28 1997/07/08 18:20:12 curt
* Working on establishing a hard ground.
*
* Revision 1.27 1997/07/07 20:59:49 curt
* Working on scenery transformations to enable us to fly fluidly over the
* poles with no discontinuity/distortion in scenery.
*
* Revision 1.26 1997/07/05 20:43:34 curt
* renamed mat3 directory to Math so we could add other math related routines.
*
* Revision 1.25 1997/06/29 21:19:17 curt
* Working on scenery management system.
*
* Revision 1.24 1997/06/26 22:14:53 curt
* Beginning work on a scenery management system.
*
* Revision 1.23 1997/06/26 19:08:33 curt
* Restructuring make, adding automatic "make dep" support.
*
* Revision 1.22 1997/06/25 15:39:47 curt
* Minor changes to compile with rsxnt/win32.
*
* Revision 1.21 1997/06/22 21:44:41 curt
* Working on intergrating the VRML (subset) parser.
*
* Revision 1.20 1997/06/21 17:12:53 curt
* Capitalized subdirectory names.
*
* Revision 1.19 1997/06/18 04:10:31 curt
* A couple more runway tweaks ...
*
* Revision 1.18 1997/06/18 02:21:24 curt
* Hacked in a runway
*
* Revision 1.17 1997/06/17 16:51:58 curt
* Timer interval stuff now uses gettimeofday() instead of ftime()
*
* Revision 1.16 1997/06/17 04:19:16 curt
* More timer related tweaks with respect to view direction changes.
*
* Revision 1.15 1997/06/17 03:41:10 curt
* Nonsignal based interval timing is now working.
* This would be a good time to look at cleaning up the code structure a bit.
*
* Revision 1.14 1997/06/16 19:32:51 curt
* Starting to add general timer support.
*
* Revision 1.13 1997/06/02 03:40:06 curt
* A tiny bit more view tweaking.
*
* Revision 1.12 1997/06/02 03:01:38 curt
* Working on views (side, front, back, transitions, etc.)
*
* Revision 1.11 1997/05/31 19:16:25 curt
* Elevator trim added.
*
* Revision 1.10 1997/05/31 04:13:52 curt
* WE CAN NOW FLY!!!
*
* Continuing work on the LaRCsim flight model integration.
* Added some MSFS-like keyboard input handling.
*
* Revision 1.9 1997/05/30 19:27:01 curt
* The LaRCsim flight model is starting to look like it is working.
*
* Revision 1.8 1997/05/30 03:54:10 curt
* Made a bit more progress towards integrating the LaRCsim flight model.
*
* Revision 1.7 1997/05/29 22:39:49 curt
* Working on incorporating the LaRCsim flight model.
*
* Revision 1.6 1997/05/29 12:31:39 curt
* Minor tweaks, moving towards general flight model integration.
*
* Revision 1.5 1997/05/29 02:33:23 curt
* Updated to reflect changing interfaces in other "modules."
*
* Revision 1.4 1997/05/27 17:44:31 curt
* Renamed & rearranged variables and routines. Added some initial simple
* timer/alarm routines so the flight model can be updated on a regular
* interval.
*
* Revision 1.3 1997/05/23 15:40:25 curt
* Added GNU copyright headers.
* Fog now works!
*
* Revision 1.2 1997/05/23 00:35:12 curt
* Trying to get fog to work ...
*
* Revision 1.1 1997/05/21 15:57:51 curt
* Renamed due to added GLUT support.
*
* Revision 1.3 1997/05/19 18:22:42 curt
* Parameter tweaking ... starting to stub in fog support.
*
* Revision 1.2 1997/05/17 00:17:34 curt
* Trying to stub in support for standard OpenGL.
*
* Revision 1.1 1997/05/16 16:05:52 curt
* Initial revision.
*
*/