[Add] Implement delta time game loop.

client/src/game_state.cpp

@@ -94,11 +94,11 @@ void GameState::handle_event(SDL_Event* event, int screen_width, int screen_heig
   }
 }
 
-void GameState::update(void) {
+void GameState::update(float dt) {
   switch(_current_screen) {
   case Screen::MAIN_MENU: {
     if(!_main_menu) break;
-    Screen next_screen = _main_menu->update();
+    Screen next_screen = _main_menu->update(dt);
     if(next_screen != Screen::MAIN_MENU) {
       const MenuButton* clicked_button = _main_menu->get_clicked_button();
       if(clicked_button) {
@@ -196,7 +196,7 @@ void GameState::update(void) {
          * TODO: These fuck'in window dimensions just need to be global at this point!!
          * Pass GameState by reference ?
          */
-        _desktop->update(_screen_width, _screen_height);
+        _desktop->update(dt, _screen_width, _screen_height);
       }
       break;
     }

client/src/game_state.h

@@ -26,7 +26,7 @@ public:
   void init(int screen_width, int screen_height);
   void start_single_player_now(int screen_width, int screen_height);
   void handle_event(SDL_Event* event, int screen_width, int screen_height);
-  void update(void);
+  void update(float dt);
   void render(const RenderContext& context);
 
 private:

client/src/main.cpp

@@ -4,6 +4,7 @@
 #include <GL/glew.h>
 #include <SDL3/SDL.h>
 #include <SDL3/SDL_keyboard.h>
+#include <SDL3/SDL_timer.h>
 
 #include "gfx/shape_renderer.h"
 #include "gfx/txt_renderer.h"
@@ -94,6 +95,10 @@ int main(int argc, char** argv) {
   Uint32 last_blink_time = 0;
   bool show_cursor = true;
 
+  /* Timestep. */
+  Uint64 last_frame_time = SDL_GetPerformanceCounter();
+  float dt = 0.0f;
+
   bool running = true;
   while(running) {
     /* Event handling. */
@@ -103,7 +108,15 @@ int main(int argc, char** argv) {
       game_state->handle_event(&event, SCREEN_WIDTH, SCREEN_HEIGHT);
     }
 
-    game_state->update();
+    /* Calculate delta time. */
+    Uint64 current_frame_time = SDL_GetPerformanceCounter();
+    dt = (current_frame_time - last_frame_time) / (float)SDL_GetPerformanceFrequency();
+    last_frame_time = current_frame_time;
+
+    /* Clamp dt to avoid large jumps. */
+    if(dt > 0.1f) dt = 0.1f;
+
+    game_state->update(dt);
 
     Uint32 current_time = SDL_GetTicks();
     if(current_time - last_blink_time > 500) { /* Every 500ms. */

client/src/ui/desktop.cpp

@@ -162,7 +162,7 @@ void Desktop::handle_event(SDL_Event* event, int screen_width, int screen_height
   }
 }
 
-void Desktop::update(int screen_width, int screen_height) {
+void Desktop::update(float dt, int screen_width, int screen_height) {
   /* Remove closed windows. */
   if(_focused_window) {
     IWindowContent* content = _focused_window->get_content();
@@ -189,7 +189,7 @@ void Desktop::update(int screen_width, int screen_height) {
       window->update();
     }
   }
-  _update_wallpaper(screen_width, screen_height);
+  _update_wallpaper(dt, screen_width, screen_height);
   _windows.erase(std::remove_if(_windows.begin(), _windows.end(),
                                 [this](const std::unique_ptr<UIWindow>& w) {
                                   if (w->should_close()) {
@@ -237,9 +237,9 @@ void Desktop::_render_wallpaper(UIRenderer* ui_renderer) {
   }
 }
 
-void Desktop::_update_wallpaper(int screen_width, int screen_height) {
+void Desktop::_update_wallpaper(float dt, int screen_width, int screen_height) {
   for(auto& line : _background_text) {
-    line.y_precise -= line.speed;
+    line.y_precise -= line.speed * dt * 100.0f;
     line.render_y = static_cast<int>(std::round(line.y_precise));
     if(line.render_y < 0) {
       line.y_precise = screen_height;

client/src/ui/desktop.h

@@ -27,7 +27,7 @@ public:
 
   void add_window(std::unique_ptr<UIWindow> window);
   void handle_event(SDL_Event* event, int screen_width, int screen_height);
-  void update(int screen_width, int screen_height);
+  void update(float dt, int screen_width, int screen_height);
   void render(const RenderContext& context);
 
   UIWindow* get_focused_window(void);
@@ -35,7 +35,7 @@ public:
 private:
   void _set_focused_window(UIWindow* window);
   void _render_wallpaper(UIRenderer* ui_renderer);
-  void _update_wallpaper(int screen_width, int screen_height);
+  void _update_wallpaper(float dt, int screen_width, int screen_height);
 
   std::vector<std::unique_ptr<UIWindow>> _windows;
   std::unique_ptr<Taskbar>   _taskbar;

client/src/ui/main_menu.cpp

@@ -89,8 +89,8 @@ void MainMenu::handle_event(SDL_Event* event) {
   }
 }
 
-Screen MainMenu::update(void) {
+Screen MainMenu::update(float dt) {
-  _update_background();
+  _update_background(dt);
   return _next_screen;
 }
 
@@ -127,9 +127,9 @@ void MainMenu::render(UIRenderer* ui_renderer) {
   ui_renderer->flush_text();
 }
 
-void MainMenu::_update_background(void) {
+void MainMenu::_update_background(float dt) {
   for(auto& line : _background_text) {
-    line.y -= line.speed;
+    line.y -= line.speed * dt * 100.0f;
     if(line.y < 0) {
       line.y = _screen_height;
       line.x = (float)(rand() % _screen_width);

client/src/ui/main_menu.h

@@ -23,13 +23,13 @@ public:
   ~MainMenu(void);
 
   void handle_event(SDL_Event* event);
-  Screen update(void);
+  Screen update(float dt);
   void render(UIRenderer* ui_renderer);
 
   const MenuButton* get_clicked_button(void) const { return _clicked_button; }
 
 private:
-  void _update_background(void);
+  void _update_background(float dt);
   void _render_background(UIRenderer* ui_renderer);
 
   /* For animated background. */