Re-write Timer class (#15)

Re-write `Timer` class to fire a user-defined callback function at a regular user-defined interval (i.e. make `Timer` generic and thus more reusable). * Also extracted the notion of frame time from the class since that's really more of an `Engine` concern.

Author: htmlboss

MP-APS/Engine.cpp

@@ -1,5 +1,6 @@
 #include "Engine.h"
 
+#include "Timer.h"
 #include "Input.h"
 #include "ViewFrustum.h"
 #include "ResourceManager.h"
@@ -31,6 +32,16 @@ void connectWindowInstanceToInput(GLFWwindow* window) {
 glfwSetCursorPosCallback(window, cursorPosCallback);
 }
 
+/***********************************************************************************/
+double frameTimeMilliseconds(const unsigned int numFramesRendered) {
+return 1000.0 / static_cast<double>(numFramesRendered);
+}
+
+/***********************************************************************************/
+double framesPerSecond(const double frameTimeMilliseconds) {
+return 1.0 / (frameTimeMilliseconds / 1000.0);
+}
+
 /***********************************************************************************/
 Engine::Engine(const std::filesystem::path& configPath) {
 
@@ -92,11 +103,28 @@ void Engine::Execute() {
 std::cout << "Engine initialization complete!\n";
 std::cout << "**************************************************\n";
 
+bool hasOneSecondPassed{ false };
+Timer timer(1.0, [&]() {
+hasOneSecondPassed = true;
+});
+
 // Main loop
+unsigned int numFramesRendered{ 0 };
 while (!m_window.ShouldClose()) {
+timer.Update(glfwGetTime());
+
+if (hasOneSecondPassed) {
+const auto frameTime{ frameTimeMilliseconds(numFramesRendered) };
+std::cout << 
+"Frame time: " <<
+frameTime << " ms - " <<
+framesPerSecond(frameTime) << " fps\n";
+
+numFramesRendered = 0;
+hasOneSecondPassed = false;
+}
 
-m_timer.Update(glfwGetTime());
-const auto dt{ m_timer.GetDelta() };
+const auto dt{ timer.GetDelta() };
 
 Input::GetInstance().Update();
 
@@ -114,6 +142,8 @@ void Engine::Execute() {
 m_guiSystem.Render();
 
 m_window.SwapBuffers();
+
+++numFramesRendered;
 }
 
 shutdown();

MP-APS/Engine.h

@@ -1,5 +1,4 @@
 #pragma once
-#include "Timer.h"
 #include "Camera.h"
 
 #include "Core/WindowSystem.h"
@@ -27,7 +26,6 @@ class Engine {
 // Returns meshes visible by the camera.
 std::vector<ModelPtr> cullViewFrustum() const;
 
-Timer m_timer;
 Camera m_camera;
 
 // Core Systems

MP-APS/Timer.cpp

@@ -1,17 +1,32 @@
 #pragma once
-#include <cstdint>
+
+#include <functional>
 
 class Timer {
+using TimerCallbackFunc = std::function<void()>;
 public:
-Timer() noexcept;
+
+Timer(const double secondsBetweenCallbackTriggers, TimerCallbackFunc callback) 
+: m_secondsBetweenCallbackTriggers{ secondsBetweenCallbackTriggers },
+ m_callbackFunc{ callback } {}
+
+void Update(const double time) {
+if (time - m_prevTriggerTime >= m_secondsBetweenCallbackTriggers) {
+m_callbackFunc();
+
+m_prevTriggerTime += m_secondsBetweenCallbackTriggers;
+}
 
-Timer(const Timer&) = delete;
-Timer& operator=(const Timer&) = delete;
+m_delta = time - m_prevTime;
+m_prevTime = time;
+}
 
-void Update(const double time) noexcept;
-auto GetDelta() const noexcept { return m_delta; }
+auto GetDelta() const noexcept {
+return m_delta;
+}
 
 private:
-double m_delta, m_lastFrame, m_lastTime;
-uint32_t m_nbFrames;
+double m_prevTriggerTime{ 0.0 }, m_prevTime{ 0.0 }, m_delta{ 0.0 };
+const double m_secondsBetweenCallbackTriggers;
+const TimerCallbackFunc m_callbackFunc;
 };