From 30660b1f451eca8a0aa45310d6bb4e1eef932b03 Mon Sep 17 00:00:00 2001
From: kj16609 <bigskyman02@gmail.com>
Date: Thu, 25 Jan 2024 05:30:28 -0500
Subject: [PATCH] Add an average framerate for the previous 120 frames

---
 src/engine/Average.hpp       | 40 ++++++++++++++++++++++++++++++++++++
 src/engine/CMakeLists.txt    |  8 ++++----
 src/engine/EngineContext.cpp | 21 +++++++++++++++----
 3 files changed, 61 insertions(+), 8 deletions(-)
 create mode 100644 src/engine/Average.hpp

diff --git a/src/engine/Average.hpp b/src/engine/Average.hpp
new file mode 100644
index 0000000..1e2c85d
--- /dev/null
+++ b/src/engine/Average.hpp
@@ -0,0 +1,40 @@
+//
+// Created by kj16609 on 1/25/24.
+//
+
+#pragma once
+
+#include <concepts>
+#include <numeric>
+
+template < typename T, std::uint64_t max_count = 100 >
+	requires std::is_integral_v< T > || std::is_floating_point_v< T >
+class Average
+{
+	std::array< T, max_count > data {};
+
+  public:
+
+	std::array< T, max_count >& getData() { return data; }
+
+	consteval std::uint64_t count() const { return max_count; }
+
+	void push( const T t )
+	{
+		std::array< T, max_count > shift_array {};
+		for ( std::uint64_t i = 1; i < max_count; ++i )
+		{
+			shift_array[ i - 1 ] = data[ i ];
+		}
+
+		shift_array[ max_count - 1 ] = t;
+		data = shift_array;
+	}
+
+	T average() const
+	{
+		const T accum { std::accumulate( data.begin(), data.end(), T() ) };
+
+		return accum / static_cast< T >( data.size() );
+	}
+};
diff --git a/src/engine/CMakeLists.txt b/src/engine/CMakeLists.txt
index b926c13..8c4ffb9 100644
--- a/src/engine/CMakeLists.txt
+++ b/src/engine/CMakeLists.txt
@@ -26,8 +26,8 @@ target_include_directories(FGLEngine PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/..)
 set_target_properties(FGLEngine PROPERTIES COMPILE_FLAGS ${FGL_FLAGS})
 
 string(TOUPPER ${CMAKE_BUILD_TYPE} CMAKE_UPPER_BUILD_TYPE)
-#if (CMAKE_UPPER_BUILD_TYPE STREQUAL "DEBUG")
-#	target_compile_definitions(FGLEngine PRIVATE ENABLE_IMGUI=1)
-#else ()
+if (CMAKE_UPPER_BUILD_TYPE STREQUAL "DEBUG")
+	target_compile_definitions(FGLEngine PRIVATE ENABLE_IMGUI=1)
+else ()
 	target_compile_definitions(FGLEngine PRIVATE ENABLE_IMGUI=0)
-#endif ()
+endif ()
diff --git a/src/engine/EngineContext.cpp b/src/engine/EngineContext.cpp
index 8f275c9..d30fab6 100644
--- a/src/engine/EngineContext.cpp
+++ b/src/engine/EngineContext.cpp
@@ -15,6 +15,7 @@
 #include <thread>
 
 #include "KeyboardMovementController.hpp"
+#include "engine/Average.hpp"
 #include "engine/buffers/UniqueFrameSuballocation.hpp"
 #include "engine/descriptors/Descriptor.hpp"
 #include "engine/descriptors/DescriptorPool.hpp"
@@ -46,6 +47,8 @@ namespace fgl::engine
 		loadGameObjects();
 	}
 
+	static Average< float, 120 > rolling_ms_average;
+
 	void EngineContext::run()
 	{
 		using namespace fgl::literals::size_literals;
@@ -99,15 +102,28 @@ namespace fgl::engine
 
 		auto current_time { std::chrono::high_resolution_clock::now() };
 
+		auto previous_frame_start { std::chrono::high_resolution_clock::now() };
+
 		while ( !m_window.shouldClose() )
 		{
 			ZoneScopedN( "Poll" );
 			glfwPollEvents();
 
 			const auto new_time { std::chrono::high_resolution_clock::now() };
+
+			{
+				//Calculate time change from previous frame and add to accumulator
+				const auto time_diff { new_time - previous_frame_start };
+				rolling_ms_average.push(
+					static_cast< float >( std::chrono::duration_cast< std::chrono::microseconds >( time_diff ).count() )
+					/ 1000.0f );
+				previous_frame_start = new_time;
+			}
+
 			auto delta_time {
 				std::chrono::duration< float, std::chrono::seconds::period >( new_time - current_time ).count()
 			};
+
 			current_time = new_time;
 			delta_time = glm::min( delta_time, MAX_DELTA_TIME );
 
@@ -163,10 +179,7 @@ namespace fgl::engine
 						ImGui::Text( "Frame Time" );
 						ImGui::SameLine();
 						ImGui::Text( "%.3f ms", 1000.0f / ImGui::GetIO().Framerate );
-
-						ImGui::Text( "Frame: " );
-						ImGui::SameLine();
-						ImGui::Text( "%i", frame_info.frame_idx );
+						ImGui::Text( "Average rolling frametime: %.3f ms", rolling_ms_average.average() );
 
 						if ( ImGui::CollapsingHeader( "Camera" ) )
 						{