From b30e525d699cbe873ddf792bb5c17cc8074dcb93 Mon Sep 17 00:00:00 2001
From: CRy386i <tetris123480@gmail.com>
Date: Mon, 25 Nov 2024 03:37:08 +0200
Subject: [PATCH] Add change Frame time POG

---
 main.c | 103 ++++++++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 91 insertions(+), 12 deletions(-)

diff --git a/main.c b/main.c
index f31a1d8..a18001a 100644
--- a/main.c
+++ b/main.c
@@ -4,58 +4,137 @@
 #include <SDL3/SDL.h>
 #include <SDL3/SDL_main.h> // only include this one in the source file with main()!
 
+#define INITIAL_FPS 60
+
 SDL_Window* window = NULL;
 SDL_Renderer* renderer = NULL;
 
+static double FPS = INITIAL_FPS;
+static double FrameTime = 1.0 / INITIAL_FPS;
+
+static double PerformancePeriod;
+
 static void panic ( const char *text ) __attribute__((noreturn));
 
+static double GetTime()
+{
+    return PerformancePeriod * SDL_GetPerformanceCounter();
+}
+
+static void SetTitle(SDL_Window * window)
+{
+    char title[48] = {0};
+    SDL_snprintf(title, sizeof(title), "Crude frame limiter @ %6.3f Hz", FPS);
+    SDL_SetWindowTitle(window, title);
+}
+
 void panic ( const char *text )
 {
-  fprintf(stderr, "ERROR: %s. %s\n", text, SDL_GetError());
-  SDL_DestroyRenderer(renderer);
-  SDL_DestroyWindow(window);
-  SDL_Quit();
-  exit(1);
+    fprintf(stderr, "ERROR: %s. %s\n", text, SDL_GetError());
+    SDL_DestroyRenderer(renderer);
+    SDL_DestroyWindow(window);
+    SDL_Quit();
+    exit(1);
 }
 
 int main( int argc, char* argv[] )
 {
     const int WIDTH = 640;
     const int HEIGHT = 480;
+    int delay_threshold = 2;
+    double sleep_time;
+    double time_counter = 0;
     bool loopShouldStop = false;
 
+    SDL_SetHint(SDL_HINT_RENDER_VSYNC, 0);
+
     if (!SDL_Init(SDL_INIT_VIDEO))
     {
         panic("SDL_Init failed");
     }
 
-    window = SDL_CreateWindow("Hello SDL", WIDTH, HEIGHT, 0);
-    if (!window) 
+    PerformancePeriod = 1.0 / SDL_GetPerformanceFrequency();
+    time_counter = GetTime();
+
+    window = SDL_CreateWindow("Hello SDL", WIDTH, HEIGHT, SDL_WINDOW_OPENGL);
+    if (!window)
     {
         panic("SDL_CreateWindow");
     }
 
     renderer = SDL_CreateRenderer(window, "opengl");
-    if (!renderer) 
+    if (!renderer)
     {
         panic("SDL_CreateRenderer");
     }
 
-    int orange = 0;
+    //SDL_GetWindowSize(window, &width, &height);
+    SetTitle(window);
+
+    //if (!SDL_SetRenderVSync(renderer, 1))
+    //{
+    //    panic("SDL_SetRenderVSync");
+    //}
+
+    SDL_HideCursor();
+
+    int red = 0;
+    int green = 0;
     while (!loopShouldStop)
     {
         SDL_Event e;
         SDL_zero(e);
         while (SDL_PollEvent(&e))
         {
-            if (e.type == SDL_EVENT_KEY_DOWN && e.key.mod == SDL_KMOD_LCTRL && e.key.key == SDLK_Q)
+            if (e.type == SDL_EVENT_QUIT)
+                loopShouldStop = true;
+            else if (e.type == SDL_EVENT_KEY_DOWN)
+            {
+                if (e.key.key == SDLK_X)
+                {
+                    FPS -= 0.1;
+                    if (FPS < 1)
+                    {
+                        FPS = 1;
+                    }
+                    FrameTime = 1.0 / FPS;
+                    SetTitle(window);
+                }
+                else if (e.key.key == SDLK_C)
+                {
+                    FPS += 0.1;
+                    FrameTime = 1.0 / FPS;
+                    SetTitle(window);
+                }
+            }
+            else if (e.key.mod == SDL_KMOD_LCTRL && e.key.key == SDLK_Q)
                 loopShouldStop = true;
         }
 
-        SDL_SetRenderDrawColor(renderer, 0, orange, 0, 255);
+        SDL_SetRenderDrawColor(renderer, red, green, 0, 255);
         SDL_RenderClear(renderer);
+
+        sleep_time = time_counter - GetTime();
+        if (sleep_time * 1000 > delay_threshold)
+        {
+            Uint32 ms = (Uint32)(sleep_time * 1000) - delay_threshold;
+            SDL_Delay(ms);
+            if (time_counter < GetTime())
+            {
+                delay_threshold++;
+                SDL_Log("Slept too long. Increased threshold to %u ms.", delay_threshold);
+            }
+        }
+
+        while (time_counter > GetTime()) {
+            /* Waiting for the right moment. */
+        }
+
         SDL_RenderPresent(renderer);
-        orange = (orange + 1) % 256;
+        red = (red + 1) % 256;
+        green = (green + 1) % 64;
+
+        time_counter += FrameTime;
     }
     SDL_DestroyRenderer(renderer);
     SDL_DestroyWindow(window);