raylib-src/examples/core/core_loading_thread.c

/*******************************************************************************************
*
*   raylib [core] example - loading thread
*
*   NOTE: This example requires linking with pthreads library on MinGW, 
*   it can be accomplished passing -static parameter to compiler
*
*   Example originally created with raylib 2.5, last time updated with raylib 3.0
*
*   Example licensed under an unmodified zlib/libpng license, which is an OSI-certified,
*
*   Copyright (c) 2014-2024 Ramon Santamaria (@raysan5)
*
********************************************************************************************/

#include "raylib.h"

// WARNING: This example does not build on Windows with MSVC compiler
#include "pthread.h"                        // POSIX style threads management

#include <stdatomic.h>                      // C11 atomic data types

#include <time.h>                           // Required for: clock()

// Using C11 atomics for synchronization
// NOTE: A plain bool (or any plain data type for that matter) can't be used for inter-thread synchronization
static atomic_bool dataLoaded = false; // Data Loaded completion indicator
static void *LoadDataThread(void *arg);     // Loading data thread function declaration

static atomic_int dataProgress = 0;                // Data progress accumulator

//------------------------------------------------------------------------------------
// Program main entry point
//------------------------------------------------------------------------------------
int main(void)
{
    // Initialization
    //--------------------------------------------------------------------------------------
    const int screenWidth = 800;
    const int screenHeight = 450;

    InitWindow(screenWidth, screenHeight, "raylib [core] example - loading thread");

    pthread_t threadId = { 0 };     // Loading data thread id

    enum { STATE_WAITING, STATE_LOADING, STATE_FINISHED } state = STATE_WAITING;
    int framesCounter = 0;

    SetTargetFPS(60);               // Set our game to run at 60 frames-per-second
    //--------------------------------------------------------------------------------------

    // Main game loop
    while (!WindowShouldClose())    // Detect window close button or ESC key
    {
        // Update
        //----------------------------------------------------------------------------------
        switch (state)
        {
            case STATE_WAITING:
            {
                if (IsKeyPressed(KEY_ENTER))
                {
                    int error = pthread_create(&threadId, NULL, &LoadDataThread, NULL);
                    if (error != 0) TraceLog(LOG_ERROR, "Error creating loading thread");
                    else TraceLog(LOG_INFO, "Loading thread initialized successfully");

                    state = STATE_LOADING;
                }
            } break;
            case STATE_LOADING:
            {
                framesCounter++;
                if (atomic_load_explicit(&dataLoaded, memory_order_relaxed))
                {
                    framesCounter = 0;
                    int error = pthread_join(threadId, NULL);
                    if (error != 0) TraceLog(LOG_ERROR, "Error joining loading thread");
                    else TraceLog(LOG_INFO, "Loading thread terminated successfully");

                    state = STATE_FINISHED;
                }
            } break;
            case STATE_FINISHED:
            {
                if (IsKeyPressed(KEY_ENTER))
                {
                    // Reset everything to launch again
                    atomic_store_explicit(&dataLoaded, false, memory_order_relaxed);
                    atomic_store_explicit(&dataProgress, 0, memory_order_relaxed);
                    state = STATE_WAITING;
                }
            } break;
            default: break;
        }
        //----------------------------------------------------------------------------------

        // Draw
        //----------------------------------------------------------------------------------
        BeginDrawing();

            ClearBackground(RAYWHITE);

            switch (state)
            {
                case STATE_WAITING: DrawText("PRESS ENTER to START LOADING DATA", 150, 170, 20, DARKGRAY); break;
                case STATE_LOADING:
                {
                    DrawRectangle(150, 200, atomic_load_explicit(&dataProgress, memory_order_relaxed), 60, SKYBLUE);
                    if ((framesCounter/15)%2) DrawText("LOADING DATA...", 240, 210, 40, DARKBLUE);

                } break;
                case STATE_FINISHED:
                {
                    DrawRectangle(150, 200, 500, 60, LIME);
                    DrawText("DATA LOADED!", 250, 210, 40, GREEN);

                } break;
                default: break;
            }

            DrawRectangleLines(150, 200, 500, 60, DARKGRAY);

        EndDrawing();
        //----------------------------------------------------------------------------------
    }

    // De-Initialization
    //--------------------------------------------------------------------------------------
    CloseWindow();        // Close window and OpenGL context
    //--------------------------------------------------------------------------------------

    return 0;
}

// Loading data thread function definition
static void *LoadDataThread(void *arg)
{
    int timeCounter = 0;            // Time counted in ms
    clock_t prevTime = clock();     // Previous time

    // We simulate data loading with a time counter for 5 seconds
    while (timeCounter < 5000)
    {
        clock_t currentTime = clock() - prevTime;
        timeCounter = currentTime*1000/CLOCKS_PER_SEC;

        // We accumulate time over a global variable to be used in
        // main thread as a progress bar
        atomic_store_explicit(&dataProgress, timeCounter/10, memory_order_relaxed);
    }

    // When data has finished loading, we set global variable
    atomic_store_explicit(&dataLoaded, true, memory_order_relaxed);

    return NULL;
}