From 08bbf6a165fa607373113ef4a6e8b13ab0395beb Mon Sep 17 00:00:00 2001
From: UnknownShadow200 <unknownshadow200@gmail.com>
Date: Sat, 25 Dec 2021 17:16:00 +1100
Subject: [PATCH] Fix LimitXYZ mode still undershooting by a couple FPS when
 moving around

This was because the frame time calculation code was not accounting for how long Window_ProcessEvents took
---
 src/Game.c           | 21 +++++++++++----------
 src/Game.h           |  2 ++
 src/Graphics_D3D11.c |  2 +-
 src/Graphics_D3D9.c  |  1 -
 src/_GLShared.h      |  2 +-
 src/_GraphicsBase.h  |  3 +--
 6 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/src/Game.c b/src/Game.c
index 6ea16a33c..3cfd48a20 100644
--- a/src/Game.c
+++ b/src/Game.c
@@ -38,6 +38,7 @@
 #include "Animations.h"
 
 struct _GameData Game;
+cc_uint64 Game_FrameStart;
 cc_bool Game_UseCPEBlocks;
 
 struct RayTracer Game_SelectedPos;
@@ -607,25 +608,24 @@ void Game_Free(void* obj) {
 }
 
 #define Game_DoFrameBody() \
+	render = Stopwatch_Measure();\
 	Window_ProcessEvents();\
 	if (!WindowInfo.Exists) return;\
 	\
-	render = Stopwatch_Measure();\
-	time   = Stopwatch_ElapsedMicroseconds(lastRender, render) / (1000.0 * 1000.0);\
+	delta  = Stopwatch_ElapsedMicroseconds(Game_FrameStart, render) / (1000.0 * 1000.0);\
 	\
-	if (time > 1.0) time = 1.0; /* avoid large delta with suspended process */ \
-	if (time > 0.0) { lastRender = Stopwatch_Measure(); Game_RenderFrame(time); }
+	if (delta > 1.0) delta = 1.0; /* avoid large delta with suspended process */ \
+	if (delta > 0.0) { Game_FrameStart = render; Game_RenderFrame(delta); }
 
 #ifdef CC_BUILD_WEB
-static cc_uint64 lastRender;
 void Game_DoFrame(void) {
 	cc_uint64 render; 
-	double time;
+	double delta;
 	Game_DoFrameBody()
 }
 
 static void Game_RunLoop(void) {
-	lastRender = Stopwatch_Measure();
+	Game_FrameStart = Stopwatch_Measure();
 	/* Window_Web.c sets Game_DoFrame as the main loop callback function */
 	/* (i.e. web browser is in charge of calling Game_DoFrame, not us) */
 }
@@ -643,9 +643,10 @@ cc_bool Game_ShouldClose(void) {
 }
 #else
 static void Game_RunLoop(void) {
-	cc_uint64 lastRender, render; 
-	double time;
-	lastRender = Stopwatch_Measure();
+	cc_uint64 render;
+	double delta;
+
+	Game_FrameStart = Stopwatch_Measure();
 	for (;;) { Game_DoFrameBody() }
 }
 #endif
diff --git a/src/Game.h b/src/Game.h
index d9b2ad7d9..43d77af09 100644
--- a/src/Game.h
+++ b/src/Game.h
@@ -16,6 +16,8 @@ CC_VAR extern struct _GameData {
 	int ChunkUpdates;
 } Game;
 
+/* Stopwatch measurement of when current frame started */
+extern cc_uint64 Game_FrameStart;
 extern struct RayTracer Game_SelectedPos;
 extern cc_bool Game_UseCPEBlocks;
 
diff --git a/src/Graphics_D3D11.c b/src/Graphics_D3D11.c
index 2a4dc394c..458b51bbe 100644
--- a/src/Graphics_D3D11.c
+++ b/src/Graphics_D3D11.c
@@ -1017,7 +1017,7 @@ void Gfx_SetFpsLimit(cc_bool vsync, float minFrameMs) {
 	gfx_minFrameMs = minFrameMs;
 	gfx_vsync      = vsync;
 }
-void Gfx_BeginFrame(void) { frameStart = Stopwatch_Measure(); }
+void Gfx_BeginFrame(void) { }
 void Gfx_Clear(void)      { OM_Clear(); }
 
 void Gfx_EndFrame(void) {
diff --git a/src/Graphics_D3D9.c b/src/Graphics_D3D9.c
index cc6aba8d9..8f16f3669 100644
--- a/src/Graphics_D3D9.c
+++ b/src/Graphics_D3D9.c
@@ -801,7 +801,6 @@ void Gfx_SetFpsLimit(cc_bool vsync, float minFrameMs) {
 
 void Gfx_BeginFrame(void) { 
 	IDirect3DDevice9_BeginScene(device);
-	frameStart = Stopwatch_Measure();
 }
 
 void Gfx_Clear(void) {
diff --git a/src/_GLShared.h b/src/_GLShared.h
index 18b80234f..7aebccdcb 100644
--- a/src/_GLShared.h
+++ b/src/_GLShared.h
@@ -268,7 +268,7 @@ void Gfx_SetFpsLimit(cc_bool vsync, float minFrameMs) {
 	if (Gfx.Created) GL_UpdateVsync();
 }
 
-void Gfx_BeginFrame(void) { frameStart = Stopwatch_Measure(); }
+void Gfx_BeginFrame(void) { }
 void Gfx_Clear(void) { glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); }
 
 void Gfx_EndFrame(void) {
diff --git a/src/_GraphicsBase.h b/src/_GraphicsBase.h
index dba073b60..749d0f141 100644
--- a/src/_GraphicsBase.h
+++ b/src/_GraphicsBase.h
@@ -22,7 +22,6 @@ static cc_bool customMipmapsLevels;
 
 static cc_bool gfx_vsync, gfx_fogEnabled;
 static float gfx_minFrameMs;
-static cc_uint64 frameStart;
 cc_bool Gfx_GetFog(void) { return gfx_fogEnabled; }
 
 /* Initialises/Restores render state */
@@ -78,7 +77,7 @@ static float gfx_targetTime, gfx_actualTime;
 /*  then sleeps if actual frame time is too fast */
 static void LimitFPS(void) {
 	cc_uint64 frameEnd = Stopwatch_Measure();
-	gfx_actualTime += Stopwatch_ElapsedMicroseconds(frameStart, frameEnd) / 1000.0f;
+	gfx_actualTime += Stopwatch_ElapsedMicroseconds(Game_FrameStart, frameEnd) / 1000.0f;
 	gfx_targetTime += gfx_minFrameMs;
 
 	/* going faster than FPS limit - sleep to slow down */