add framerate control (WIP)

src/window/Window.hpp

@@ -19,6 +19,8 @@ class Window {
     static std::stack<glm::vec4> scissorStack;
     static glm::vec4 scissorArea;
     static bool fullscreen;
+    static int framerate;
+    static double prevSwap;
 
     static bool tryToMaximize(GLFWwindow* window, GLFWmonitor* monitor);
 public:
@@ -34,7 +36,7 @@ public:
     static bool isShouldClose();
     static void setShouldClose(bool flag);
     static void swapBuffers();
-    static void swapInterval(int interval);
+    static void setFramerate(int interval);
     static void toggleFullscreen();
     static bool isFullscreen();
     static bool isMaximized();