From e238e35bb20bccaf2bb5255a6d36fa2a6cea7b42 Mon Sep 17 00:00:00 2001
From: "Grayson Riffe (Desktop)" <graysonriffe@yahoo.com>
Date: Mon, 23 Aug 2021 01:13:53 -0500
Subject: [PATCH] Refactored game loop to use less CPU

---
 NothinFancy/src/Application.cpp          | 15 ++++++++-------
 NothinFancy/src/Renderer/IndexBuffer.cpp |  2 +-
 NothinFancy/src/Utility.cpp              |  3 +--
 NothinFancy/src/include/Application.h    |  5 ++---
 NothinFancy/src/include/Renderer.h       |  1 +
 5 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/NothinFancy/src/Application.cpp b/NothinFancy/src/Application.cpp
index 12471bd..f5f1882 100644
--- a/NothinFancy/src/Application.cpp
+++ b/NothinFancy/src/Application.cpp
@@ -140,8 +140,11 @@ namespace nf {
 	void Application::startMainThread() {
 		m_renderer = new Renderer(this);
 		startIntroState();
+		std::chrono::steady_clock::time_point start_time = std::chrono::steady_clock::now();
+		const std::chrono::duration<double> wait_time = std::chrono::nanoseconds(1000000000 / 60);
+		auto next_time = start_time + wait_time;
 		while (m_running) {
-			m_deltaTime = m_fpsDuration.count();
+			start_time = std::chrono::steady_clock::now();
 			m_currentState->update();
 			m_currentState->render();
 			m_renderer->doFrame();
@@ -149,16 +152,14 @@ namespace nf {
 			m_fpsClock2 = std::chrono::steady_clock::now();
 			m_fpsDuration = m_fpsClock2 - m_fpsClock1;
 			if (m_fpsDuration.count() >= 1.0) {
-				m_fpsClock1 = std::chrono::steady_clock::now();
 				m_FPS = m_frames;
 				m_frames = 0;
 				Log("FPS: " + std::to_string(m_FPS));
+				m_fpsClock1 = std::chrono::steady_clock::now();
 			}
-			m_fpsDuration = std::chrono::steady_clock::now() - m_frameClock;
-			while (m_fpsDuration.count() < m_minFrametime) {
-				m_fpsDuration = std::chrono::steady_clock::now() - m_frameClock;
-			}
-			m_frameClock = std::chrono::steady_clock::now();
+			std::this_thread::sleep_until(next_time);
+			m_deltaTime = (std::chrono::steady_clock::now() - start_time).count();
+			next_time += wait_time;
 		}
 		m_currentState->onExit();
 		delete m_renderer;
diff --git a/NothinFancy/src/Renderer/IndexBuffer.cpp b/NothinFancy/src/Renderer/IndexBuffer.cpp
index 047992b..6382133 100644
--- a/NothinFancy/src/Renderer/IndexBuffer.cpp
+++ b/NothinFancy/src/Renderer/IndexBuffer.cpp
@@ -5,7 +5,7 @@ namespace nf {
 		m_count = count;
 		glGenBuffers(1, &m_id);
 		glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_id);
-		glBufferData(GL_ELEMENT_ARRAY_BUFFER, count * sizeof(unsigned int), data, GL_STATIC_DRAW);//TODO: See if I need to change this to dynamic
+		glBufferData(GL_ELEMENT_ARRAY_BUFFER, count * sizeof(unsigned int), data, GL_STATIC_DRAW);
 	}
 
 	void IndexBuffer::bind() const {
diff --git a/NothinFancy/src/Utility.cpp b/NothinFancy/src/Utility.cpp
index 2347400..2a66909 100644
--- a/NothinFancy/src/Utility.cpp
+++ b/NothinFancy/src/Utility.cpp
@@ -1,4 +1,3 @@
-//TODO: File IO functions
 #include <Windows.h>
 
 #include "Utility.h"
@@ -72,7 +71,7 @@ namespace nf {
 		out.close();
 		return true;
 	}
-
+	//TODO: XOR encryption
 	std::string readFile(const char* filename) {
 		std::ifstream in;
 		in.open(filename);
diff --git a/NothinFancy/src/include/Application.h b/NothinFancy/src/include/Application.h
index 2de15cc..e38df10 100644
--- a/NothinFancy/src/include/Application.h
+++ b/NothinFancy/src/include/Application.h
@@ -50,11 +50,10 @@ namespace nf {
 		LONG m_defaultWindowStyle;
 		WINDOWPLACEMENT m_wndPlacement;
 
-		std::chrono::steady_clock::time_point m_frameClock = std::chrono::steady_clock::now();
 		std::chrono::duration<double> m_fpsDuration;
 		double m_deltaTime;
-		std::chrono::steady_clock::time_point m_fpsClock1 = m_frameClock;
-		std::chrono::steady_clock::time_point m_fpsClock2 = m_frameClock;
+		std::chrono::steady_clock::time_point m_fpsClock1 = std::chrono::steady_clock::now();
+		std::chrono::steady_clock::time_point m_fpsClock2 = m_fpsClock1;
 		int m_frames;
 		const int m_targetFPS = 60;
 		const double m_minFrametime = 1.0 / m_targetFPS;
diff --git a/NothinFancy/src/include/Renderer.h b/NothinFancy/src/include/Renderer.h
index aa4b769..65a39aa 100644
--- a/NothinFancy/src/include/Renderer.h
+++ b/NothinFancy/src/include/Renderer.h
@@ -6,6 +6,7 @@
 
 namespace nf {
 	class Application;
+
 	class Renderer {
 	public:
 		Renderer(Application* app);