ADDED: Example: core_custom_frame_control

examples/core/core_custom_frame_control.c

@@ -0,0 +1,126 @@
+/*******************************************************************************************
+*
+*   raylib [core] example - custom frame control
+*
+*   WARNING: This is an example for advance users willing to have full control over
+*   the frame processes. By default, EndDrawing() calls the following processes:
+*       1. Draw remaining batch data: rlDrawRenderBatchActive()
+*       2. SwapScreenBuffer()
+*       3. Frame time control: WaitTime()
+*       4. PollInputEvents()
+*
+*   To avoid steps 2, 3 and 4, flag SUPPORT_CUSTOM_FRAME_CONTROL can be enabled in
+*   config.h (it requires recompiling raylib). This way those steps are up to the user.
+*
+*   Note that enabling this flag invalidates some functions:
+*       - GetFrameTime()
+*       - SetTargetFPS()
+*       - GetFPS()
+*
+*   This example has been created using raylib 3.8 (www.raylib.com)
+*   raylib is licensed under an unmodified zlib/libpng license (View raylib.h for details)
+*
+*   Copyright (c) 2021 Ramon Santamaria (@raysan5)
+*
+********************************************************************************************/
+
+#include "raylib.h"
+
+int main(void)
+{
+    // Initialization
+    //--------------------------------------------------------------------------------------
+    const int screenWidth = 800;
+    const int screenHeight = 450;
+    
+    InitWindow(screenWidth, screenHeight, "raylib [core] example - custom frame control");
+
+    // Custom timming variables
+    double previousTime = GetTime();    // Previous time measure
+    double currentTime = 0.0;           // Current time measure
+    double updateDrawTime = 0.0;        // Update + Draw time
+    double waitTime = 0.0;              // Wait time (if target fps required)
+    float deltaTime = 0.0f;             // Frame time (Update + Draw + Wait time)
+    
+    float timeCounter = 0.0f;           // Accumulative time counter (seconds)
+    float position = 0.0f;              // Circle position
+    bool pause = false;                 // Pause control flag
+    
+    int targetFPS = 60;                 // Our initial target fps
+    //--------------------------------------------------------------------------------------
+
+    // Main game loop
+    while (!WindowShouldClose())        // Detect window close button or ESC key
+    {
+        // Update
+        //----------------------------------------------------------------------------------
+        PollInputEvents();              // Poll input events (SUPPORT_CUSTOM_FRAME_CONTROL)
+        
+        if (IsKeyPressed(KEY_SPACE)) pause = !pause;
+        
+        if (IsKeyPressed(KEY_UP)) targetFPS += 20;
+        else if (IsKeyPressed(KEY_DOWN)) targetFPS -= 20;
+        
+        if (targetFPS < 0) targetFPS = 0;
+
+        if (!pause)
+        {
+            position += 200*deltaTime;  // We move at 200 pixels per second
+
+            if (position >= GetScreenWidth()) position = 0;
+            
+            timeCounter += deltaTime;   // We count time (seconds)
+        }
+        //----------------------------------------------------------------------------------
+
+        // Draw
+        //----------------------------------------------------------------------------------
+        BeginDrawing();
+
+            ClearBackground(RAYWHITE);
+
+            for (int i = 0; i < GetScreenWidth()/200; i++) DrawRectangle(200*i, 0, 1, GetScreenHeight(), SKYBLUE);
+            
+            DrawCircle((int)position, GetScreenHeight()/2 - 25, 50, RED);
+            
+            DrawText(FormatText("%03.0f ms", timeCounter*1000.0f), position - 40, GetScreenHeight()/2 - 100, 20, MAROON);
+            DrawText(FormatText("PosX: %03.0f", position), position - 50, GetScreenHeight()/2 + 40, 20, BLACK);
+            
+            DrawText("Circle is moving at a constant 200 pixels/sec,\nindependently of the frame rate.", 10, 10, 20, DARKGRAY);
+            DrawText("PRESS SPACE to PAUSE MOVEMENT", 10, GetScreenHeight() - 30, 20, GRAY);
+            DrawText(FormatText("TARGET FPS: %i", targetFPS), GetScreenWidth() - 220, 10, 20, LIME);
+            DrawText(FormatText("CURRENT FPS: %i", (int)(1.0f/deltaTime)), GetScreenWidth() - 220, 40, 20, GREEN);
+
+        EndDrawing();
+
+        // NOTE: In case raylib is configured to SUPPORT_CUSTOM_FRAME_CONTROL, 
+        // Events polling, screen buffer swap and frame time control must be managed by the user
+
+        SwapScreenBuffer();         // Flip the back buffer to screen (front buffer)
+        
+        currentTime = GetTime();
+        updateDrawTime = currentTime - previousTime;
+        
+        if (targetFPS > 0)          // We want a fixed frame rate
+        {
+            waitTime = (1.0f/(float)targetFPS) - updateDrawTime;
+            if (waitTime > 0.0) 
+            {
+                WaitTime((float)waitTime*1000.0f);
+                currentTime = GetTime();
+                deltaTime = (float)(currentTime - previousTime);
+            }
+        }
+        else deltaTime = updateDrawTime;    // Framerate could be variable
+
+        previousTime = currentTime;
+        //----------------------------------------------------------------------------------
+    }
+
+    // De-Initialization
+    //--------------------------------------------------------------------------------------
+    CloseWindow();        // Close window and OpenGL context
+    //--------------------------------------------------------------------------------------
+
+    return 0;
+}