feat!: rework header files

inc/core/time.hpp

@@ -0,0 +1,30 @@
+#ifndef TIME_HPP
+#define TIME_HPP
+
+#include "GLFW/glfw3.h"
+
+class Time
+{
+ private:
+  double deltaTime = 0.;
+  double lastDTime = 0.;
+
+ public:
+  double getDeltaTime() const { return deltaTime; }
+  double getLastDeltaTime() const { return lastDTime; }
+
+  void start()
+  {
+    deltaTime = glfwGetTime();
+    lastDTime = 0.;
+  }
+
+  void update()
+  {
+    double currentTime = glfwGetTime();
+    deltaTime = currentTime - lastDTime;
+    lastDTime = currentTime;
+  }
+};
+
+#endif