src/Main/main.cxx

   1 // main.cxx -- top level sim routines
   2 //
   3 // Written by Curtis Olson, started May 1997.
   4 //
   5 // Copyright (C) 1997 - 2002  Curtis L. Olson  - http://www.flightgear.org/~curt
   6 //
   7 // This program is free software; you can redistribute it and/or
   8 // modify it under the terms of the GNU General Public License as
   9 // published by the Free Software Foundation; either version 2 of the
  10 // License, or (at your option) any later version.
  11 //
  12 // This program is distributed in the hope that it will be useful, but
  13 // WITHOUT ANY WARRANTY; without even the implied warranty of
  14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15 // General Public License for more details.
  16 //
  17 // You should have received a copy of the GNU General Public License
  18 // along with this program; if not, write to the Free Software
  19 // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  20 //
  21 // $Id$
  22
  23
  24 #ifdef HAVE_CONFIG_H
  25 #  include <config.h>
  26 #endif
  27
  28 #include <simgear/compiler.h>
  29
  30 #if defined(__linux__) && defined(__i386__)
  31 #  include <fpu_control.h>
  32 #  include <signal.h>
  33 #endif
  34
  35 #include <iostream>
  36
  37 #include <osg/Camera>
  38 #include <osg/GraphicsContext>
  39 #include <osgDB/Registry>
  40
  41 // Class references
  42 #include <simgear/scene/model/modellib.hxx>
  43 #include <simgear/scene/material/matlib.hxx>
  44 #include <simgear/scene/model/animation.hxx>
  45 #include <simgear/scene/sky/sky.hxx>
  46 #include <simgear/structure/event_mgr.hxx>
  47 #include <simgear/props/AtomicChangeListener.hxx>
  48 #include <simgear/props/props.hxx>
  49 #include <simgear/timing/sg_time.hxx>
  50 #include <simgear/math/sg_random.h>
  51
  52 #include <Time/light.hxx>
  53 #include <Aircraft/replay.hxx>
  54 #include <Cockpit/cockpit.hxx>
  55 #include <Cockpit/hud.hxx>
  56 #include <Model/panelnode.hxx>
  57 #include <Model/modelmgr.hxx>
  58 #include <Model/acmodel.hxx>
  59 #include <Scenery/scenery.hxx>
  60 #include <Scenery/tilemgr.hxx>
  61 #include <Sound/fg_fx.hxx>
  62 #include <Sound/beacon.hxx>
  63 #include <Sound/morse.hxx>
  64 #include <Sound/fg_fx.hxx>
  65 #include <ATCDCL/ATCmgr.hxx>
  66 #include <Time/TimeManager.hxx>
  67 #include <Environment/environment_mgr.hxx>
  68 #include <Environment/ephemeris.hxx>
  69 #include <GUI/new_gui.hxx>
  70 #include <MultiPlayer/multiplaymgr.hxx>
  71
  72 #include "CameraGroup.hxx"
  73 #include "fg_commands.hxx"
  74 #include "fg_io.hxx"
  75 #include "renderer.hxx"
  76 #include "splash.hxx"
  77 #include "main.hxx"
  78 #include "util.hxx"
  79 #include "fg_init.hxx"
  80 #include "fg_os.hxx"
  81 #include "WindowSystemAdapter.hxx"
  82 #include <Main/viewer.hxx>
  83
  84
  85 using namespace flightgear;
  86
  87 using std::cerr;
  88
  89 // Specify our current idle function state.  This is used to run all
  90 // our initializations out of the idle callback so that we can get a
  91 // splash screen up and running right away.
  92 int idle_state = 0;
  93
  94
  95 void fgInitSoundManager();
  96 void fgSetNewSoundDevice(const char *);
  97
  98 // The atexit() function handler should know when the graphical subsystem
  99 // is initialized.
 100 extern int _bootstrap_OSInit;
 101
 102 // What should we do when we have nothing else to do?  Let's get ready
 103 // for the next move and update the display?
 104 static void fgMainLoop( void ) {
 105
 106     static SGConstPropertyNode_ptr longitude
 107         = fgGetNode("/position/longitude-deg");
 108     static SGConstPropertyNode_ptr latitude
 109         = fgGetNode("/position/latitude-deg");
 110     static SGConstPropertyNode_ptr altitude
 111         = fgGetNode("/position/altitude-ft");
 112     static SGConstPropertyNode_ptr vn_fps
 113         = fgGetNode("/velocities/speed-north-fps");
 114     static SGConstPropertyNode_ptr ve_fps
 115         = fgGetNode("/velocities/speed-east-fps");
 116     static SGConstPropertyNode_ptr vd_fps
 117         = fgGetNode("/velocities/speed-down-fps");
 118
 119     static SGPropertyNode_ptr frame_signal
 120         = fgGetNode("/sim/signals/frame", true);
 121
 122     frame_signal->fireValueChanged();
 123     SGCloudLayer::enable_bump_mapping = fgGetBool("/sim/rendering/bump-mapping");
 124
 125     SG_LOG( SG_ALL, SG_DEBUG, "Running Main Loop");
 126     SG_LOG( SG_ALL, SG_DEBUG, "======= ==== ====");
 127
 128
 129   // update "time"
 130     double sim_dt, real_dt;
 131     TimeManager* timeMgr = (TimeManager*) globals->get_subsystem("time");
 132     // compute simulated time (allowing for pause, warp, etc) and
 133     // real elapsed time
 134     timeMgr->computeTimeDeltas(sim_dt, real_dt);
 135
 136     if (globals->get_warp_delta() != 0) {
 137         FGLight *l = (FGLight *)(globals->get_subsystem("lighting"));
 138         l->update( 0.5 );
 139     }
 140
 141     // update magvar model
 142     globals->get_mag()->update( longitude->getDoubleValue()
 143                                 * SGD_DEGREES_TO_RADIANS,
 144                                 latitude->getDoubleValue()
 145                                 * SGD_DEGREES_TO_RADIANS,
 146                                 altitude->getDoubleValue() * SG_FEET_TO_METER,
 147                                 globals->get_time_params()->getJD() );
 148
 149
 150     // Update any multiplayer's network queues, the AIMultiplayer
 151     // implementation is an AI model and depends on that
 152     globals->get_multiplayer_mgr()->Update();
 153
 154 #if ENABLE_ATCDCL
 155     // Run ATC subsystem
 156     if (fgGetBool("/sim/atc/enabled"))
 157         globals->get_ATC_mgr()->update(sim_dt);
 158 #endif
 159
 160     globals->get_subsystem_mgr()->update(sim_dt);
 161
 162     // run Nasal's settimer() loops right before the view manager
 163     globals->get_event_mgr()->update(sim_dt);
 164
 165     // pick up model coordidnates that Nasal code may have set relative to the
 166     // aircraft's
 167     globals->get_model_mgr()->update(sim_dt);
 168
 169     // update the view angle as late as possible, but before sound calculations
 170     globals->get_viewmgr()->update(real_dt);
 171
 172     // Update the sound manager last so it can use the CPU while the GPU
 173     // is processing the scenery (doubled the frame-rate for me) -EMH-
 174 #ifdef ENABLE_AUDIO_SUPPORT
 175     static bool smgr_init = true;
 176     static SGPropertyNode *sound_working = fgGetNode("/sim/sound/working");
 177     if (smgr_init == true) {
 178         if (sound_working->getBoolValue() == true) {
 179             fgInitSoundManager();
 180             smgr_init = false;
 181         }
 182     } else {
 183         static SGPropertyNode *sound_enabled = fgGetNode("/sim/sound/enabled");
 184         static SGSoundMgr *smgr = globals->get_soundmgr();
 185         static bool smgr_enabled = true;
 186
 187         if (sound_working->getBoolValue() == false) {   // request to reinit
 188            smgr->reinit();
 189            smgr->resume();
 190            sound_working->setBoolValue(true);
 191         }
 192
 193         if (smgr_enabled != sound_enabled->getBoolValue()) {
 194             if (smgr_enabled == true) { // request to suspend
 195                 smgr->suspend();
 196                 smgr_enabled = false;
 197             } else {
 198                 smgr->resume();
 199                 smgr_enabled = true;
 200             }
 201         }
 202
 203         if (smgr_enabled == true) {
 204             static SGPropertyNode *volume = fgGetNode("/sim/sound/volume");
 205             smgr->set_volume(volume->getFloatValue());
 206             smgr->update(sim_dt);
 207         }
 208     }
 209 #endif
 210
 211     // END Tile Manager udpates
 212     bool scenery_loaded = fgGetBool("sim/sceneryloaded");
 213     if (!scenery_loaded && globals->get_tile_mgr()->isSceneryLoaded()
 214         && fgGetBool("sim/fdm-initialized")) {
 215         fgSetBool("sim/sceneryloaded",true);
 216         if (fgGetBool("/sim/sound/working")) {
 217             globals->get_soundmgr()->activate();
 218         }
 219         globals->get_props()->tie("/sim/sound/devices/name",
 220               SGRawValueFunctions<const char *>(0, fgSetNewSoundDevice), false);
 221     }
 222     simgear::AtomicChangeListener::fireChangeListeners();
 223
 224     SG_LOG( SG_ALL, SG_DEBUG, "" );
 225 }
 226
 227 void fgInitSoundManager()
 228 {
 229     SGSoundMgr *smgr = globals->get_soundmgr();
 230
 231     smgr->bind();
 232     smgr->init(fgGetString("/sim/sound/device-name", NULL));
 233
 234     vector <const char*>devices = smgr->get_available_devices();
 235     for (unsigned int i=0; i<devices.size(); i++) {
 236         SGPropertyNode *p = fgGetNode("/sim/sound/devices/device", i, true);
 237         p->setStringValue(devices[i]);
 238     }
 239     devices.clear();
 240 }
 241
 242 void fgSetNewSoundDevice(const char *device)
 243 {
 244     globals->get_soundmgr()->suspend();
 245     globals->get_soundmgr()->stop();
 246     globals->get_soundmgr()->init(device);
 247     globals->get_soundmgr()->resume();
 248 }
 249
 250 // Operation for querying OpenGL parameters. This must be done in a
 251 // valid OpenGL context, potentially in another thread.
 252 namespace
 253 {
 254 struct GeneralInitOperation : public GraphicsContextOperation
 255 {
 256     GeneralInitOperation()
 257         : GraphicsContextOperation(std::string("General init"))
 258     {
 259     }
 260     void run(osg::GraphicsContext* gc)
 261     {
 262         SGPropertyNode* simRendering = fgGetNode("/sim/rendering");
 263
 264         simRendering->setStringValue("gl-vendor", (char*) glGetString(GL_VENDOR));
 265         SG_LOG( SG_GENERAL, SG_INFO, glGetString(GL_VENDOR));
 266
 267         simRendering->setStringValue("gl-renderer", (char*) glGetString(GL_RENDERER));
 268         SG_LOG( SG_GENERAL, SG_INFO, glGetString(GL_RENDERER));
 269
 270         simRendering->setStringValue("gl-version", (char*) glGetString(GL_VERSION));
 271         SG_LOG( SG_GENERAL, SG_INFO, glGetString(GL_VERSION));
 272
 273         GLint tmp;
 274         glGetIntegerv( GL_MAX_TEXTURE_SIZE, &tmp );
 275         simRendering->setIntValue("max-texture-size", tmp);
 276
 277         glGetIntegerv( GL_DEPTH_BITS, &tmp );
 278         simRendering->setIntValue("depth-buffer-bits", tmp);
 279     }
 280 };
 281
 282
 283 osg::Node* load_panel(SGPropertyNode *n)
 284 {
 285     osg::Geode* geode = new osg::Geode;
 286     geode->addDrawable(new FGPanelNode(n));
 287     return geode;
 288 }
 289
 290 SGPath resolve_path(const std::string& s)
 291 {
 292   return globals->resolve_maybe_aircraft_path(s);
 293 }
 294
 295 }
 296
 297 // This is the top level master main function that is registered as
 298 // our idle funciton
 299
 300 // The first few passes take care of initialization things (a couple
 301 // per pass) and once everything has been initialized fgMainLoop from
 302 // then on.
 303
 304 static void fgIdleFunction ( void ) {
 305     static osg::ref_ptr<GeneralInitOperation> genOp;
 306     if ( idle_state == 0 ) {
 307         idle_state++;
 308         // Pick some window on which to do queries.
 309         // XXX Perhaps all this graphics initialization code should be
 310         // moved to renderer.cxx?
 311         genOp = new GeneralInitOperation;
 312         osg::Camera* guiCamera = getGUICamera(CameraGroup::getDefault());
 313         WindowSystemAdapter* wsa = WindowSystemAdapter::getWSA();
 314         osg::GraphicsContext* gc = 0;
 315         if (guiCamera)
 316             gc = guiCamera->getGraphicsContext();
 317         if (gc) {
 318             gc->add(genOp.get());
 319         } else {
 320             wsa->windows[0]->gc->add(genOp.get());
 321         }
 322         guiStartInit(gc);
 323     } else if ( idle_state == 1 ) {
 324         if (genOp.valid()) {
 325             if (!genOp->isFinished())
 326                 return;
 327             genOp = 0;
 328         }
 329         if (!guiFinishInit())
 330             return;
 331         idle_state++;
 332         fgSplashProgress("reading aircraft list");
 333
 334
 335     } else if ( idle_state == 2 ) {
 336         idle_state++;
 337
 338         fgSplashProgress("reading airport & navigation data");
 339
 340
 341     } else if ( idle_state == 3 ) {
 342         idle_state++;
 343         fgInitNav();
 344         fgSplashProgress("setting up scenery");
 345
 346
 347     } else if ( idle_state == 4 ) {
 348         idle_state++;
 349         // based on the requested presets, calculate the true starting
 350         // lon, lat
 351         fgInitPosition();
 352         fgInitTowerLocationListener();
 353
 354         TimeManager* t = new TimeManager;
 355         globals->add_subsystem("time", t, SGSubsystemMgr::INIT);
 356         t->init(); // need to init now, not during initSubsystems
 357
 358         // Do some quick general initializations
 359         if( !fgInitGeneral()) {
 360             SG_LOG( SG_GENERAL, SG_ALERT,
 361                 "General initialization failed ..." );
 362             exit(-1);
 363         }
 364
 365         ////////////////////////////////////////////////////////////////////
 366         // Initialize the property-based built-in commands
 367         ////////////////////////////////////////////////////////////////////
 368         fgInitCommands();
 369
 370
 371         ////////////////////////////////////////////////////////////////////
 372         // Initialize the material manager
 373         ////////////////////////////////////////////////////////////////////
 374         globals->set_matlib( new SGMaterialLib );
 375         simgear::SGModelLib::init(globals->get_fg_root());
 376         simgear::SGModelLib::setPropRoot(globals->get_props());
 377         simgear::SGModelLib::setPanelFunc(load_panel);
 378
 379         ////////////////////////////////////////////////////////////////////
 380         // Initialize the TG scenery subsystem.
 381         ////////////////////////////////////////////////////////////////////
 382         globals->set_scenery( new FGScenery );
 383         globals->get_scenery()->init();
 384         globals->get_scenery()->bind();
 385         globals->set_tile_mgr( new FGTileMgr );
 386
 387
 388         ////////////////////////////////////////////////////////////////////
 389         // Initialize the general model subsystem.
 390         ////////////////////////////////////////////////////////////////////
 391         globals->set_model_mgr(new FGModelMgr);
 392         globals->get_model_mgr()->init();
 393         globals->get_model_mgr()->bind();
 394         fgSplashProgress("loading aircraft");
 395
 396
 397     } else if ( idle_state == 5 ) {
 398         idle_state++;
 399
 400         ////////////////////////////////////////////////////////////////////
 401         // Initialize the 3D aircraft model subsystem (has a dependency on
 402         // the scenery subsystem.)
 403         ////////////////////////////////////////////////////////////////////
 404         FGAircraftModel* acm = new FGAircraftModel;
 405         globals->set_aircraft_model(acm);
 406         globals->add_subsystem("aircraft-model", acm, SGSubsystemMgr::DISPLAY);
 407
 408         ////////////////////////////////////////////////////////////////////
 409         // Initialize the view manager subsystem.
 410         ////////////////////////////////////////////////////////////////////
 411         FGViewMgr *viewmgr = new FGViewMgr;
 412         globals->set_viewmgr( viewmgr );
 413         viewmgr->init();
 414         viewmgr->bind();
 415         fgSplashProgress("generating sky elements");
 416
 417
 418     } else if ( idle_state == 6 ) {
 419         idle_state++;
 420         // Initialize the sky
 421
 422         Ephemeris* eph = new Ephemeris;
 423         globals->add_subsystem("ephemeris", eph);
 424         eph->init(); // FIXME - remove this once SGSky code below is also a subsystem
 425         eph->bind();
 426
 427         // TODO: move to environment mgr
 428         thesky = new SGSky;
 429         SGPath texture_path(globals->get_fg_root());
 430         texture_path.append("Textures");
 431         texture_path.append("Sky");
 432         for (int i = 0; i < FGEnvironmentMgr::MAX_CLOUD_LAYERS; i++) {
 433             SGCloudLayer * layer = new SGCloudLayer(texture_path.str());
 434             thesky->add_cloud_layer(layer);
 435         }
 436
 437         SGPath sky_tex_path( globals->get_fg_root() );
 438         sky_tex_path.append( "Textures" );
 439         sky_tex_path.append( "Sky" );
 440         thesky->texture_path( sky_tex_path.str() );
 441
 442         // The sun and moon diameters are scaled down numbers of the
 443         // actual diameters. This was needed to fit both the sun and the
 444         // moon within the distance to the far clip plane.
 445         // Moon diameter:    3,476 kilometers
 446         // Sun diameter: 1,390,000 kilometers
 447         thesky->build( 80000.0, 80000.0,
 448                        463.3, 361.8,
 449                        *globals->get_ephem(),
 450                        fgGetNode("/environment", true));
 451
 452         // Initialize MagVar model
 453         SGMagVar *magvar = new SGMagVar();
 454         globals->set_mag( magvar );
 455
 456
 457                                     // kludge to initialize mag compass
 458                                     // (should only be done for in-flight
 459                                     // startup)
 460         // update magvar model
 461         globals->get_mag()->update( fgGetDouble("/position/longitude-deg")
 462                                     * SGD_DEGREES_TO_RADIANS,
 463                                     fgGetDouble("/position/latitude-deg")
 464                                     * SGD_DEGREES_TO_RADIANS,
 465                                     fgGetDouble("/position/altitude-ft")
 466                                     * SG_FEET_TO_METER,
 467                                     globals->get_time_params()->getJD() );
 468         double var = globals->get_mag()->get_magvar() * SGD_RADIANS_TO_DEGREES;
 469         fgSetDouble("/instrumentation/heading-indicator/offset-deg", -var);
 470         fgSetDouble("/instrumentation/heading-indicator-fg/offset-deg", -var);
 471
 472
 473         // airport = new ssgBranch;
 474         // airport->setName( "Airport Lighting" );
 475         // lighting->addKid( airport );
 476
 477         // build our custom render states
 478         fgSplashProgress("initializing subsystems");
 479
 480
 481     } else if ( idle_state == 7 ) {
 482         idle_state++;
 483         // Initialize audio support
 484 #ifdef ENABLE_AUDIO_SUPPORT
 485
 486         // Start the intro music
 487         if ( fgGetBool("/sim/startup/intro-music") ) {
 488             SGPath mp3file( globals->get_fg_root() );
 489             mp3file.append( "Sounds/intro.mp3" );
 490
 491             SG_LOG( SG_GENERAL, SG_INFO,
 492                 "Starting intro music: " << mp3file.str() );
 493
 494 # if defined( __CYGWIN__ )
 495             string command = "start /m `cygpath -w " + mp3file.str() + "`";
 496 # elif defined( _WIN32 )
 497             string command = "start /m " + mp3file.str();
 498 # else
 499             string command = "mpg123 " + mp3file.str() + "> /dev/null 2>&1";
 500 # endif
 501
 502             system ( command.c_str() );
 503         }
 504 #endif
 505         // This is the top level init routine which calls all the
 506         // other subsystem initialization routines.  If you are adding
 507         // a subsystem to flightgear, its initialization call should be
 508         // located in this routine.
 509         if( !fgInitSubsystems()) {
 510             SG_LOG( SG_GENERAL, SG_ALERT,
 511                 "Subsystem initialization failed ..." );
 512             exit(-1);
 513         }
 514         fgSplashProgress("setting up time & renderer");
 515
 516
 517     } else if ( idle_state == 8 ) {
 518         idle_state = 1000;
 519
 520         // setup OpenGL view parameters
 521         globals->get_renderer()->init();
 522
 523         globals->get_renderer()->resize( fgGetInt("/sim/startup/xsize"),
 524                                          fgGetInt("/sim/startup/ysize") );
 525
 526         fgSplashProgress("loading scenery objects");
 527         int session = fgGetInt("/sim/session",0);
 528         session++;
 529         fgSetInt("/sim/session",session);
 530     }
 531
 532     if ( idle_state == 1000 ) {
 533         // We've finished all our initialization steps, from now on we
 534         // run the main loop.
 535         fgSetBool("sim/sceneryloaded", false);
 536         fgRegisterIdleHandler( fgMainLoop );
 537     }
 538 }
 539
 540
 541 static void upper_case_property(const char *name)
 542 {
 543     using namespace simgear;
 544     SGPropertyNode *p = fgGetNode(name, false);
 545     if (!p) {
 546         p = fgGetNode(name, true);
 547         p->setStringValue("");
 548     } else {
 549         props::Type t = p->getType();
 550         if (t == props::NONE || t == props::UNSPECIFIED)
 551             p->setStringValue("");
 552         else
 553             assert(t == props::STRING);
 554     }
 555     p->addChangeListener(new FGMakeUpperCase);
 556 }
 557
 558
 559 // Main top level initialization
 560 int fgMainInit( int argc, char **argv ) {
 561
 562     // set default log levels
 563     sglog().setLogLevels( SG_ALL, SG_ALERT );
 564
 565     string version;
 566 #ifdef FLIGHTGEAR_VERSION
 567     version = FLIGHTGEAR_VERSION;
 568 #else
 569     version = "unknown version";
 570 #endif
 571     SG_LOG( SG_GENERAL, SG_INFO, "FlightGear:  Version "
 572             << version );
 573     SG_LOG( SG_GENERAL, SG_INFO, "Built with " << SG_COMPILER_STR << endl );
 574
 575     // Allocate global data structures.  This needs to happen before
 576     // we parse command line options
 577
 578     globals = new FGGlobals;
 579
 580     // seed the random number generator
 581     sg_srandom_time();
 582
 583     FGControls *controls = new FGControls;
 584     globals->set_controls( controls );
 585
 586     string_list *col = new string_list;
 587     globals->set_channel_options_list( col );
 588
 589     fgValidatePath("", false);  // initialize static variables
 590     upper_case_property("/sim/presets/airport-id");
 591     upper_case_property("/sim/presets/runway");
 592     upper_case_property("/sim/tower/airport-id");
 593     upper_case_property("/autopilot/route-manager/input");
 594
 595     // Scan the config file(s) and command line options to see if
 596     // fg_root was specified (ignore all other options for now)
 597     fgInitFGRoot(argc, argv);
 598
 599     // Check for the correct base package version
 600     static char required_version[] = "2.0.0";
 601     string base_version = fgBasePackageVersion();
 602     if ( !(base_version == required_version) ) {
 603         // tell the operator how to use this application
 604
 605         SG_LOG( SG_GENERAL, SG_ALERT, "" ); // To popup the console on windows
 606         cerr << endl << "Base package check failed ... " \
 607              << "Found version " << base_version << " at: " \
 608              << globals->get_fg_root() << endl;
 609         cerr << "Please upgrade to version: " << required_version << endl;
 610 #ifdef _MSC_VER
 611         cerr << "Hit a key to continue..." << endl;
 612         cin.get();
 613 #endif
 614         exit(-1);
 615     }
 616
 617     // Load the configuration parameters.  (Command line options
 618     // override config file options.  Config file options override
 619     // defaults.)
 620     if ( !fgInitConfig(argc, argv) ) {
 621         SG_LOG( SG_GENERAL, SG_ALERT, "Config option parsing failed ..." );
 622         exit(-1);
 623     }
 624
 625     // Initialize the Window/Graphics environment.
 626     fgOSInit(&argc, argv);
 627     _bootstrap_OSInit++;
 628
 629     fgRegisterWindowResizeHandler( &FGRenderer::resize );
 630     fgRegisterIdleHandler( &fgIdleFunction );
 631     fgRegisterDrawHandler( &FGRenderer::update );
 632
 633     // Initialize plib net interface
 634     netInit( &argc, argv );
 635
 636     // Clouds3D requires an alpha channel
 637     fgOSOpenWindow(true /* request stencil buffer */);
 638
 639     // Initialize the splash screen right away
 640     fntInit();
 641     fgSplashInit();
 642
 643     // pass control off to the master event handler
 644     int result = fgOSMainLoop();
 645
 646     // clean up here; ensure we null globals to avoid
 647     // confusing the atexit() handler
 648     delete globals;
 649     globals = NULL;
 650
 651     return result;
 652 }
 653
 654