new example: core_loading_thread

Data loading in a second thread with progress bar in main thread

examples/core/core_loading_thread.c

@@ -0,0 +1,133 @@
+/*******************************************************************************************
+*
+*   raylib example - loading thread
+*
+*   NOTE: This example requires linking with pthreads library, 
+*   on MinGW, it can be accomplished passing -static parameter to compiler
+*
+*   This example has been created using raylib 2.5 (www.raylib.com)
+*   raylib is licensed under an unmodified zlib/libpng license (View raylib.h for details)
+*
+*   Copyright (c) 2014-2019 Ramon Santamaria (@raysan5)
+*
+********************************************************************************************/
+
+#include "raylib.h"
+
+#include "pthread.h"                        // POSIX style threads management
+
+#include <time.h>                           // Required for clock() function
+
+static bool dataLoaded = false;             // Loading data semaphore
+static void *LoadDataThread(void *arg);     // Loading data thread function declaration
+
+static int dataProgress = 0;                // Data progress accumulator
+
+int main()
+{
+    // Initialization
+    //--------------------------------------------------------------------------------------
+    int screenWidth = 800;
+    int screenHeight = 450;
+
+    InitWindow(screenWidth, screenHeight, "raylib [core] example - loading thread");
+    
+    pthread_t threadId;             // Loading data thread id
+
+    int state = 0;                  // 0-Waiting, 1-Loading, 2-Finished
+    int framesCounter = 0;
+
+    SetTargetFPS(60);
+    //--------------------------------------------------------------------------------------
+
+    // Main game loop
+    while (!WindowShouldClose())    // Detect window close button or ESC key
+    {
+        // Update
+        //----------------------------------------------------------------------------------
+        if (state == 0)
+        {
+            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 = 1;
+            }
+        }
+        else if (state == 1)
+        {
+            framesCounter++;
+            if (dataLoaded) 
+            {
+                framesCounter = 0;
+                state = 2;
+            }
+        }
+        else if (state == 2)
+        {
+            if (IsKeyPressed(KEY_ENTER)) 
+            {
+                // Reset everything to launch again
+                dataLoaded = false;
+                dataProgress = 0;
+                state = 0;
+            }
+        }
+        //----------------------------------------------------------------------------------
+
+        // Draw
+        //----------------------------------------------------------------------------------
+        BeginDrawing();
+
+            ClearBackground(RAYWHITE);
+            
+            if (state == 0) DrawText("PRESS ENTER to START LOADING DATA", 150, 170, 20, DARKGRAY);
+            else if (state == 1) 
+            { 
+                DrawRectangle(150, 200, dataProgress, 60, SKYBLUE);
+                if ((framesCounter/15)%2) DrawText("LOADING DATA...", 240, 210, 40, DARKBLUE);
+            }
+            else if (state == 2) 
+            {
+                DrawRectangle(150, 200, 500, 60, LIME);
+                DrawText("DATA LOADED!", 250, 210, 40, GREEN);
+            }
+            
+            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
+        dataProgress = timeCounter/10;
+    }
+
+    // When data has finished loading, we set global variable
+    dataLoaded = true;
+
+    return NULL;
+}