src/vg/vg.h

   1 /* Copyright (C) 2021-2022 Harry Godden (hgn) - All Rights Reserved */
   2
   3 /*
   4  * Memory model:
   5  *    [global (.data)] [temp-stack] [system-stack] [game-heap]
   6  *
   7  *    1. Program starts: .data memory is loaded
   8  *    2. System initialization:
   9  *       2a. the large heap buffer is allocated
  10  *       2b. each engine system is initialized in order, using some of the
  11  *           system stack
  12  *       2c. game systems are also put into here
  13  */
  14
  15
  16 #ifndef VG_HEADER_H
  17 #define VG_HEADER_H
  18
  19 #include "vg_platform.h"
  20 #include "vg_mem.h"
  21
  22 #ifndef _WIN32
  23 #include <execinfo.h>
  24 #endif
  25
  26
  27 #if defined(VG_SERVER) || defined(VG_TOOLS)
  28  #define VG_NON_CLIENT
  29 #endif
  30
  31 #ifndef VG_SERVER
  32 #include "../../dep/glad/glad.h"
  33
  34 #define GLFW_INCLUDE_GLCOREARB
  35
  36 #ifdef _WIN32
  37   #define GLFW_DLL
  38 #endif
  39
  40 #include "../../dep/glfw/glfw3.h"
  41 #endif
  42
  43 #include "vg_stdint.h"
  44
  45 void vg_register_exit( void( *funcptr )(void), const char *name );
  46
  47 #include "vg_m.h"
  48 #include "vg_io.h"
  49 #include "vg_log.h"
  50
  51 #ifdef VG_STEAM
  52 //#include "vg_steamworks.h"
  53 #include "vg_steam.h"
  54 #endif
  55
  56 #ifndef VG_NON_CLIENT
  57
  58 struct vg
  59 {
  60    /* Engine sync */
  61    GLFWwindow* window;
  62
  63    vg_mutex     mux_context;
  64    vg_semaphore sem_allow_exec,
  65                 sem_exec_finished,
  66                 sem_loader,
  67                 sem_fatal;
  68    int exec_context;
  69
  70    vg_mutex     mux_engine_status;
  71    enum engine_status
  72    {
  73       k_engine_status_none,
  74       k_engine_status_running,
  75       k_engine_status_crashed
  76    }
  77    engine_status;
  78    const char *str_const_engine_err;
  79    int          is_loaded;
  80
  81    /* Window information */
  82    int window_x,
  83        window_y,
  84        samples;
  85    float refresh_rate;
  86
  87    v2f mouse,
  88        mouse_wheel;
  89
  90    /* Runtime */
  91    double time,
  92           time_delta,
  93           frame_delta,
  94           time_real,
  95           time_real_last,
  96           time_rate,
  97           accumulator;
  98
  99    int fixed_iterations;
 100
 101    enum engine_stage
 102    {
 103       k_engine_stage_none,
 104       k_engine_stage_update,
 105       k_engine_stage_update_fixed,
 106       k_engine_stage_rendering,
 107       k_engine_stage_ui
 108    }
 109    engine_stage;
 110
 111    /* graphics */
 112    m4x4f pv;
 113    enum quality_profile
 114    {
 115       k_quality_profile_high = 0,
 116       k_quality_profile_low = 1,
 117    }
 118    quality_profile;
 119
 120    /* Gamepad */
 121    GLFWgamepadstate  gamepad;
 122    int                        gamepad_ready;
 123    const char       *gamepad_name;
 124    int                        gamepad_id;
 125 }
 126 VG_STATIC vg = { .time_rate = 1.0 };
 127
 128 struct vg_thread_info
 129 {
 130    enum vg_thread_purpose
 131    {
 132       k_thread_purpose_nothing,
 133       k_thread_purpose_main,
 134       k_thread_purpose_loader
 135    }
 136    purpose;
 137
 138    int gl_context_level;
 139 };
 140
 141 static VG_THREAD_LOCAL struct vg_thread_info vg_thread_info;
 142
 143
 144 //#define VG_SYNC_DEBUG
 145
 146 #ifdef VG_SYNC_DEBUG
 147   #define VG_SYNC_LOG(STR,...) vg_info(STR,vg_thread_info.purpose,##__VA_ARGS__)
 148 #else
 149   #define VG_SYNC_LOG(...)
 150 #endif
 151
 152 VG_STATIC void vg_fatal_exit_loop( const char *error );
 153 VG_STATIC void vg_required( void *ptr, const char *path )
 154 {
 155    if( !ptr )
 156    {
 157       vg_fatal_exit_loop( path );
 158    }
 159 }
 160
 161
 162 VG_STATIC void vg_ensure_engine_running(void)
 163 {
 164    /* Check if the engine is no longer running */
 165    vg_mutex_lock( &vg.mux_engine_status );
 166    if( vg.engine_status != k_engine_status_running )
 167    {
 168       VG_SYNC_LOG( "[%d] Engine is no longer running\n");
 169       vg_mutex_unlock( &vg.mux_engine_status );
 170
 171       /* Safe to disregard loader thread from this point on, elswhere */
 172       if( vg_thread_info.purpose == k_thread_purpose_loader )
 173       {
 174          vg_semaphore_post( &vg.sem_loader );
 175       }
 176
 177       VG_SYNC_LOG( "[%d] about to kill\n");
 178       vg_thread_exit();
 179    }
 180    vg_mutex_unlock( &vg.mux_engine_status );
 181 }
 182
 183 /*
 184  * Sync execution so that the OpenGL context is switched onto this thread.
 185  * Anything after this call will be in a valid context.
 186  */
 187 VG_STATIC void vg_acquire_thread_sync(void)
 188 {
 189    /* We dont want to do anything if this is the main thread */
 190    if( vg_thread_info.purpose == k_thread_purpose_main )
 191       return;
 192
 193    assert( vg_thread_info.purpose == k_thread_purpose_loader );
 194
 195    vg_ensure_engine_running();
 196
 197    /* Check if thread already has the context */
 198    if( vg_thread_info.gl_context_level )
 199    {
 200       vg_thread_info.gl_context_level ++;
 201       VG_SYNC_LOG( "[%d] We already have sync here\n" );
 202       return;
 203    }
 204
 205    vg_mutex_lock( &vg.mux_context );
 206    VG_SYNC_LOG( "[%d] Signal to sync.\n" );
 207    vg.exec_context = 1;
 208    vg_mutex_unlock( &vg.mux_context );
 209
 210    /* wait until told we can go */
 211    VG_SYNC_LOG( "[%d] Waiting to acuire sync.\n" );
 212    vg_semaphore_wait( &vg.sem_allow_exec );
 213    glfwMakeContextCurrent( vg.window );
 214
 215    /* context now valid to work in while we hold up main thread */
 216    VG_SYNC_LOG( "[%d] Context acquired.\n" );
 217    vg_thread_info.gl_context_level ++;
 218 }
 219
 220 /*
 221  * Signify that we are done with the OpenGL context in this thread.
 222  * Anything after this call will be in an undefined context.
 223  */
 224 VG_STATIC void vg_release_thread_sync(void)
 225 {
 226    if( vg_thread_info.purpose == k_thread_purpose_main )
 227       return;
 228
 229    assert( vg_thread_info.purpose == k_thread_purpose_loader );
 230
 231    /* signal that we are done */
 232    vg_thread_info.gl_context_level --;
 233
 234    if( !vg_thread_info.gl_context_level )
 235    {
 236       VG_SYNC_LOG( "[%d] Releasing context.\n" );
 237       glfwMakeContextCurrent( NULL );
 238       vg_semaphore_post( &vg.sem_exec_finished );
 239    }
 240 }
 241
 242 VG_STATIC void vg_run_synced_content(void)
 243 {
 244    assert( vg_thread_info.purpose == k_thread_purpose_main );
 245
 246    vg_mutex_lock( &vg.mux_context );
 247
 248    if( vg.exec_context != 0 )
 249    {
 250       VG_SYNC_LOG( "[%d] Allowing content (%d).\n", vg.exec_context );
 251
 252       /* allow operations to go */
 253       vg_thread_info.gl_context_level = 0;
 254       glfwMakeContextCurrent( NULL );
 255       vg_semaphore_post( &vg.sem_allow_exec );
 256
 257       /* wait for operations to complete */
 258       VG_SYNC_LOG( "[%d] Waiting for content (%d).\n", vg.exec_context );
 259       vg_semaphore_wait( &vg.sem_exec_finished );
 260
 261       /* check if we killed the engine */
 262       vg_ensure_engine_running();
 263
 264       /* re-engage main thread */
 265       VG_SYNC_LOG( "[%d] Re-engaging.\n" );
 266       vg.exec_context = 0;
 267       glfwMakeContextCurrent( vg.window );
 268       vg_thread_info.gl_context_level = 1;
 269    }
 270
 271    vg_mutex_unlock( &vg.mux_context );
 272 }
 273
 274 VG_STATIC void vg_opengl_sync_init(void)
 275 {
 276    vg_semaphore_init( &vg.sem_allow_exec, 0 );
 277    vg_semaphore_init( &vg.sem_exec_finished, 0 );
 278    vg_semaphore_init( &vg.sem_loader, 1 );
 279    vg_semaphore_init( &vg.sem_fatal, 1 );
 280    vg_mutex_init( &vg.mux_context );
 281
 282    vg_set_thread_name( "[vg] Main" );
 283    vg_thread_info.purpose = k_thread_purpose_main;
 284    vg_thread_info.gl_context_level = 1;
 285 }
 286
 287 VG_STATIC void vg_checkgl( const char *src_info );
 288 #define VG_STRINGIT( X ) #X
 289 #define VG_CHECK_GL_ERR() vg_checkgl( __FILE__ ":L" VG_STRINGIT(__LINE__) )
 290
 291 #include "vg_console.h"
 292 #include "vg_profiler.h"
 293 #include "vg_audio.h"
 294 #include "vg_shader.h"
 295 #include "vg_tex.h"
 296 #include "vg_input.h"
 297 #include "vg_ui.h"
 298 #include "vg_lines.h"
 299 #include "vg_loader.h"
 300 #include "vg_opt.h"
 301
 302 /* Diagnostic */
 303 VG_STATIC struct vg_profile vg_prof_update = {.name="update()"},
 304                             vg_prof_render = {.name="render()"};
 305
 306 #define VG_GAMELOOP
 307 VG_STATIC void vg_register(void) VG_GAMELOOP;
 308 VG_STATIC void vg_start(void) VG_GAMELOOP;
 309
 310 VG_STATIC void vg_update(int loaded) VG_GAMELOOP;
 311 VG_STATIC void vg_update_fixed(int loaded) VG_GAMELOOP;
 312 VG_STATIC void vg_update_post(int loaded) VG_GAMELOOP;
 313
 314 VG_STATIC void vg_framebuffer_resize(int w, int h) VG_GAMELOOP;
 315 VG_STATIC void vg_render(void) VG_GAMELOOP;
 316 VG_STATIC void vg_ui(void) VG_GAMELOOP;
 317
 318 VG_STATIC void vg_checkgl( const char *src_info )
 319 {
 320    int fail = 0;
 321
 322    GLenum err;
 323    while( (err = glGetError()) != GL_NO_ERROR )
 324    {
 325       vg_error( "(%s) OpenGL Error: #%d\n", src_info, err );
 326       fail = 1;
 327    }
 328
 329    if( fail )
 330       vg_fatal_exit_loop( "OpenGL Error" );
 331 }
 332
 333 void vg_mouse_callback( GLFWwindow* ptrW, double xpos, double ypos )
 334 {
 335    vg.mouse[0] = xpos;
 336    vg.mouse[1] = ypos;
 337 }
 338
 339 void vg_scroll_callback( GLFWwindow* ptrW, double xoffset, double yoffset )
 340 {
 341    vg.mouse_wheel[0] += xoffset;
 342    vg.mouse_wheel[1] += yoffset;
 343 }
 344
 345 void vg_framebuffer_resize_callback( GLFWwindow *ptrW, int w, int h )
 346 {
 347    if( !w || !h )
 348    {
 349       vg_warn( "Got a invalid framebuffer size: %dx%d... ignoring\n", w, h );
 350       return;
 351    }
 352
 353    vg.window_x = w;
 354    vg.window_y = h;
 355
 356    vg_framebuffer_resize(w,h);
 357 }
 358
 359 VG_STATIC void vg_bake_shaders(void)
 360 {
 361    vg_acquire_thread_sync();
 362
 363 #if 0
 364    vg_function_push( (struct vg_cmd)
 365    {
 366       .name = "shaders",
 367       .function = vg_shaders_live_recompile
 368    });
 369 #endif
 370
 371    vg_shaders_compile();
 372    vg_release_thread_sync();
 373 }
 374
 375 VG_STATIC void vg_preload(void);
 376 VG_STATIC void vg_load(void);
 377 VG_STATIC void vg_load_full(void)
 378 {
 379    vg_preload();
 380
 381    /* internal */
 382    vg_loader_highwater( vg_gamepad_init, NULL, NULL );
 383    vg_loader_highwater( vg_lines_init, NULL, NULL );
 384    vg_loader_highwater( vg_audio_init, vg_audio_free, NULL );
 385    vg_loader_highwater( vg_profiler_init, NULL, NULL );
 386
 387    /* client */
 388    vg_load();
 389
 390    vg_acquire_thread_sync();
 391    vg.is_loaded = 1;
 392    vg_release_thread_sync();
 393 }
 394
 395 VG_STATIC void vg_enter( int argc, char *argv[], const char *window_name )
 396 {
 397    char *arg;
 398    while( vg_argp( argc, argv ) )
 399    {
 400       if( (arg = vg_opt_arg( 'w' )) )
 401       {
 402          vg.window_x = atoi( arg );
 403       }
 404
 405       if( (arg = vg_opt_arg( 'h' )) )
 406       {
 407          vg.window_y = atoi( arg );
 408       }
 409
 410       if( (arg = vg_long_opt_arg( "samples" )) )
 411       {
 412          vg.samples = VG_MAX( 0, VG_MIN( 8, atoi( arg ) ) );
 413       }
 414
 415       if(  vg_long_opt( "use-libc-malloc" ) )
 416       {
 417          vg_mem.use_libc_malloc = atoi( arg );
 418       }
 419
 420       if( vg_long_opt( "high-performance" ) )
 421       {
 422          vg.quality_profile = k_quality_profile_low;
 423       }
 424    }
 425
 426    vg_alloc_quota();
 427    vg_log_init();
 428    vg_console_init();
 429
 430    glfwInit();
 431    glfwWindowHint( GLFW_CONTEXT_VERSION_MAJOR, 3 );
 432    glfwWindowHint( GLFW_CONTEXT_VERSION_MINOR, 3 );
 433    glfwWindowHint( GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE );
 434    //glfwWindowHint( GLFW_OPENGL_DEBUG_CONTEXT, GL_FALSE );
 435    glfwWindowHint( GLFW_CONTEXT_RELEASE_BEHAVIOR, GLFW_RELEASE_BEHAVIOR_FLUSH );
 436
 437    glfwWindowHint( GLFW_RESIZABLE, GLFW_FALSE );
 438    glfwWindowHint( GLFW_DOUBLEBUFFER, GLFW_TRUE );
 439
 440    glfwWindowHint( GLFW_SAMPLES, vg.samples );
 441
 442    GLFWmonitor *monitor_primary = glfwGetPrimaryMonitor();
 443
 444    const GLFWvidmode *mode = glfwGetVideoMode( monitor_primary );
 445    glfwWindowHint( GLFW_RED_BITS, mode->redBits );
 446    glfwWindowHint( GLFW_GREEN_BITS, mode->greenBits );
 447    glfwWindowHint( GLFW_BLUE_BITS, mode->blueBits );
 448
 449    glfwWindowHint( GLFW_REFRESH_RATE, mode->refreshRate );
 450
 451    if( !vg.window_x )
 452       vg.window_x = mode->width;
 453
 454    if( !vg.window_y )
 455       vg.window_y = mode->height;
 456
 457    vg.refresh_rate = mode->refreshRate;
 458
 459    if( (vg.window = glfwCreateWindow(  vg.window_x, vg.window_y,
 460                                        window_name, monitor_primary, NULL)) )
 461    {
 462       glfwGetFramebufferSize( vg.window, &vg.window_x, &vg.window_y );
 463       vg_success( "Window created (%dx%d)\n", vg.window_x, vg.window_y );
 464    }
 465    else
 466    {
 467       vg_error( "GLFW Failed to initialize\n" );
 468       return;
 469    }
 470
 471    /* We need 3.1.2 for correct VSync on windows */
 472    {
 473       int vmaj, vmin, vrev;
 474       glfwGetVersion( &vmaj, &vmin, &vrev );
 475
 476       if( vmaj < 3 ||
 477          (vmaj == 3 && vmin  < 1) ||
 478          (vmaj == 3 && vmin == 1 && vrev < 2 ) )
 479       {
 480          vg_error( "GLFW out of date (%d.%d.%d); (3.1.2 is required)\n",
 481                     vmaj, vmin, vrev );
 482
 483          glfwTerminate();
 484          return;
 485       }
 486
 487       vg_success( "GLFW Version %d.%d.%d\n", vmaj, vmin, vrev );
 488    }
 489
 490    glfwMakeContextCurrent( vg.window );
 491    glfwSwapInterval( 1 );
 492
 493    glfwSetWindowSizeLimits( vg.window, 800, 600, GLFW_DONT_CARE,GLFW_DONT_CARE);
 494    glfwSetFramebufferSizeCallback( vg.window, vg_framebuffer_resize_callback );
 495
 496    glfwSetCursorPosCallback( vg.window, vg_mouse_callback );
 497    glfwSetScrollCallback( vg.window, vg_scroll_callback );
 498
 499    glfwSetCharCallback( vg.window, console_proc_wchar );
 500    glfwSetKeyCallback( vg.window, console_proc_key );
 501    glfwSetInputMode( vg.window, GLFW_CURSOR, GLFW_CURSOR_HIDDEN );
 502
 503    if( !gladLoadGLLoader((GLADloadproc)glfwGetProcAddress) )
 504    {
 505       vg_error( "Glad Failed to initialize\n" );
 506       glfwTerminate();
 507       return;
 508    }
 509
 510    const unsigned char* glver = glGetString( GL_VERSION );
 511    vg_success( "Load setup complete, OpenGL version: %s\n", glver );
 512
 513    /* init systems
 514     * -----------------------------------------------------------------------*/
 515    ui_init_context();
 516    vg_loader_init();
 517
 518    vg_mutex_init( &vg.mux_engine_status );
 519    vg.engine_status = k_engine_status_running;
 520
 521    vg_opengl_sync_init();
 522    vg_loader_start();
 523
 524    vg.accumulator = 0.75f * (1.0f/60.0f);
 525
 526    int loaded = 0;
 527    while(1)
 528    {
 529       if( glfwWindowShouldClose( vg.window ) )
 530          break;
 531
 532       v2_copy( (v2f){ 0.0f, 0.0f }, vg.mouse_wheel );
 533       glfwPollEvents();
 534
 535       vg.time_real_last = vg.time_real;
 536       vg.time_real = glfwGetTime();
 537       vg.frame_delta = vg.time_real-vg.time_real_last;
 538
 539       /* scaled time */
 540       vg.time_delta = vg.frame_delta * vg.time_rate;
 541       vg.time += vg.time_delta;
 542
 543       if( vg.is_loaded )
 544       {
 545          if( !loaded )
 546          {
 547             vg_start();
 548             loaded = 1;
 549          }
 550       }
 551       else
 552       {
 553          vg_loader_render();
 554       }
 555
 556       /*
 557        * Game logic
 558        * -------------------------------------------------------
 559        */
 560       vg_profile_begin( &vg_prof_update );
 561       vg_update_inputs();
 562
 563       vg.engine_stage = k_engine_stage_update;
 564       vg_update( loaded );
 565
 566       /* Fixed update loop */
 567       vg.engine_stage = k_engine_stage_update_fixed;
 568       vg.accumulator += vg.time_delta;
 569
 570       vg.fixed_iterations = 0;
 571       vg_lines.allow_input = 1;
 572       while( vg.accumulator >= (VG_TIMESTEP_FIXED-0.00125) )
 573       {
 574          vg_update_fixed( loaded );
 575          vg_lines.allow_input = 0;
 576
 577          vg.accumulator -= VG_TIMESTEP_FIXED;
 578          vg.accumulator  = VG_MAX( 0.0, vg.accumulator );
 579
 580          vg.fixed_iterations ++;
 581          if( vg.fixed_iterations == 8 )
 582          {
 583             break;
 584          }
 585       }
 586       vg_lines.allow_input = 1;
 587
 588       /*
 589        * Rendering
 590        * ---------------------------------------------
 591        */
 592       vg.engine_stage = k_engine_stage_update;
 593       vg_update_post( loaded );
 594       vg_profile_end( &vg_prof_update );
 595
 596       vg_profile_begin( &vg_prof_render );
 597
 598       if( loaded )
 599       {
 600          /* render */
 601          vg.engine_stage = k_engine_stage_rendering;
 602          vg_render();
 603
 604          /* ui */
 605          vg.engine_stage = k_engine_stage_ui;
 606          {
 607             ui_begin( vg.window_x, vg.window_y );
 608             ui_set_mouse( vg.mouse[0], vg.mouse[1],
 609                            vg_get_button_state( "primary" ) );
 610
 611             vg_profile_drawn(
 612                   (struct vg_profile *[]){&vg_prof_update,&vg_prof_render}, 2,
 613                   (1.0f/(float)vg.refresh_rate)*1000.0f,
 614                   (ui_rect){ 4, 4, 250, 0 }, 0
 615             );
 616
 617             if( vg_profiler )
 618             {
 619
 620                char perf[128];
 621
 622                snprintf( perf, 127,
 623                      "x: %d y: %d\n"
 624                      "refresh: %.1f (%.1fms)\n"
 625                      "samples: %d\n"
 626                      "iterations: %d (acc: %.3fms%%)\n",
 627                      vg.window_x, vg.window_y,
 628                      vg.refresh_rate, (1.0f/vg.refresh_rate)*1000.0f,
 629                      vg.samples,
 630                      vg.fixed_iterations,
 631                      (vg.accumulator/VG_TIMESTEP_FIXED)*100.0f );
 632
 633                ui_text( (ui_rect){258, 4+24+12,0,0},perf, 1,0);
 634             }
 635
 636             audio_debug_ui( vg.pv );
 637             vg_ui();
 638             vg_console_draw();
 639
 640             ui_resolve();
 641             ui_draw( NULL );
 642          }
 643       }
 644
 645       vg_profile_end( &vg_prof_render );
 646
 647       glfwSwapBuffers( vg.window );
 648       vg_run_synced_content();
 649    }
 650
 651    vg_console_write_persistent();
 652
 653    vg_mutex_lock( &vg.mux_engine_status );
 654    vg.engine_status = k_engine_status_none;
 655    vg_mutex_unlock( &vg.mux_engine_status );
 656
 657    vg_loader_free();
 658
 659    vg_success( "If you see this it means everything went.. \"well\".....\n" );
 660    glfwTerminate();
 661 }
 662
 663 /*
 664  * Immediately transfer away from calling thread into a safe loop, signal for
 665  * others to shutdown, then free everything once the user closes the window.
 666  *
 667  * FIXME(bug): glfwWindowShouldClose() never returns 1 in windows via wine, ONLY
 668  *             when calling the program from outside its normal directory.
 669  */
 670 VG_STATIC void vg_fatal_exit_loop( const char *error )
 671 {
 672    /*
 673     *    https://www.gnu.org/software/libc/manual/html_node/Backtraces.html
 674     *    thanks gnu <3
 675     *
 676     *    TODO: this on windows?
 677     */
 678
 679 #ifndef _WIN32
 680
 681    void *array[20];
 682    char **strings;
 683    int size, i;
 684
 685    size = backtrace( array, 20 );
 686    strings = backtrace_symbols( array, size );
 687
 688    if( strings != NULL )
 689    {
 690       vg_error( "---------------- gnu backtrace -------------\n" );
 691
 692       for( int i=0; i<size; i++ )
 693          vg_info( "%s\n", strings[i] );
 694
 695       vg_error( "---------------- gnu backtrace -------------\n" );
 696    }
 697
 698    free( strings );
 699
 700 #endif
 701
 702    vg_error( "Fatal error: %s\n", error );
 703    assert( vg_semaphore_trywait( &vg.sem_fatal ) );
 704
 705    vg_mutex_lock( &vg.mux_engine_status );
 706
 707    if( vg.engine_status == k_engine_status_none )
 708    {
 709       vg_mutex_unlock( &vg.mux_engine_status );
 710
 711       /* TODO: Correct shutdown before other systems */
 712       exit(0);
 713    }
 714    else
 715    {
 716       vg_mutex_unlock( &vg.mux_engine_status );
 717
 718       /*
 719        * if main
 720        *    if loader running
 721        *       wait until loader checks in, it will die
 722        *    else
 723        *       pass immediately
 724        * else
 725        *    if have context
 726        *       pass immediately
 727        *    else
 728        *       wait for main to get to us, it will never be used again
 729        *
 730        * undefined behaviour:
 731        *    fatal_exit_loop is called in both threads, preventing an appropriate
 732        *                    reaction to the crash. This *should* be made
 733        *                    obvious by the assertion
 734        */
 735       vg_acquire_thread_sync();
 736
 737       vg_mutex_lock( &vg.mux_engine_status );
 738       vg.engine_status = k_engine_status_crashed;
 739       vg.str_const_engine_err = error;
 740       vg_mutex_unlock( &vg.mux_engine_status );
 741
 742       /*
 743        * Wait for loader to finish what it was doing, if it was running.
 744        * Then we can continue in our nice error screen
 745        */
 746       if( vg_thread_info.purpose == k_thread_purpose_main )
 747       {
 748          vg_semaphore_wait( &vg.sem_loader );
 749       }
 750       vg_audio_free(NULL);
 751
 752       while(1)
 753       {
 754          if( glfwWindowShouldClose( vg.window ) )
 755             break;
 756
 757          if( glfwGetKey( vg.window, GLFW_KEY_ESCAPE ) )
 758             break;
 759
 760          glfwPollEvents();
 761
 762          glBindFramebuffer( GL_FRAMEBUFFER, 0 );
 763          glEnable(GL_BLEND);
 764          glDisable(GL_DEPTH_TEST);
 765          glBlendFunc(GL_ONE_MINUS_DST_ALPHA, GL_DST_ALPHA);
 766          glBlendEquation(GL_FUNC_ADD);
 767
 768          glClearColor( 0.15f + sinf(glfwGetTime())*0.1f, 0.0f, 0.0f,1.0f );
 769          glClear( GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT );
 770          glViewport( 0,0, vg.window_x, vg.window_y );
 771
 772          vg_render_log();
 773
 774          glfwSwapBuffers( vg.window );
 775       }
 776
 777       /* Can now shutdown and EXIT */
 778       vg_loader_free();
 779       glfwTerminate();
 780       exit(0);
 781    }
 782 }
 783
 784 #else
 785
 786 VG_STATIC void vg_fatal_exit_loop( const char *error )
 787 {
 788    vg_error( "Fatal error: %s\n", error );
 789    exit(0);
 790 }
 791
 792 #endif
 793
 794 /*
 795  * Graphic cards will check these to force it to use the GPU
 796  */
 797 u32 NvOptimusEnablement = 0x00000001;
 798 int AmdPowerXpressRequestHighPerformance = 1;
 799
 800 #endif