Stabilized main loop.

Cherry picked timeBeginPeriod.
Ref PR #85.

SpaceCadetPinball/pb.cpp

@@ -225,12 +225,15 @@ void pb::ballset(int x, int y)
 	ball->Speed = maths::normalize_2d(&ball->Acceleration);
 }
 
-int pb::frame(int time)
+void pb::frame(int time)
 {
 	static int frameTime = 0;
 
 	if (time > 100)
 		time = 100;
+	if (time <= 0)
+		return;
+
 	float timeMul = time * 0.001f;
 	if (!mode_countdown(time))
 	{
@@ -284,7 +287,6 @@ int pb::frame(int time)
 				MainTable->tilt(time_now);
 		}
 	}
-	return 1;
 }
 
 void pb::timed_frame(float timeNow, float timeDelta, bool drawBalls)

SpaceCadetPinball/pb.h

@@ -26,7 +26,7 @@ public:
 	static void toggle_demo();
 	static void replay_level(int demoMode);
 	static void ballset(int x, int y);
-	static int frame(int time);
+	static void frame(int time);
 	static void timed_frame(float timeNow, float timeDelta, bool drawBalls);
 	static void window_size(int* width, int* height);
 	static void pause_continue();

SpaceCadetPinball/winmain.cpp

@@ -12,6 +12,8 @@
 #include "splash.h"
 #include "render.h"
 
+const int TargetFrameTime = 8;
+
 HINSTANCE winmain::hinst = nullptr;
 HWND winmain::hwnd_frame = nullptr;
 HCURSOR winmain::mouse_hsave;
@@ -28,8 +30,6 @@ int winmain::last_mouse_y;
 int winmain::mouse_down;
 int winmain::no_time_loss;
 
-DWORD winmain::then;
-DWORD winmain::now;
 UINT winmain::iFrostUniqueMsg;
 bool winmain::restart = false;
 
@@ -51,6 +51,10 @@ int winmain::WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLi
 	options::ReadOptions();
 	auto regSpaceCadet = pinball::get_rc_string(166, 0);
 
+	// Needed for sub 16ms sleep
+	if (timeBeginPeriod(1) == TIMERR_NOERROR)
+		atexit(ResetTimer);
+
 	if (options::get_int(regSpaceCadet, "Table Version", 1) <= 1)
 	{
 		auto tmpBuf = memory::allocate(0x1F4u);
@@ -221,7 +225,7 @@ int winmain::WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLi
 		pb::replay_level(0);
 
 	DWORD someTimeCounter = 300u, prevTime = 0u;
-	then = timeGetTime();
+	int sleepRemainder = 0, frameDuration = TargetFrameTime;
 	while (true)
 	{
 		if (!someTimeCounter)
@@ -259,38 +263,26 @@ int winmain::WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLi
 
 		if (has_focus)
 		{
-			if (mouse_down)
+			if (mouse_down && frameDuration >= 2)
-			{
-				now = timeGetTime();
-				if (now - then >= 2)
 			{
 				/*last_mouse_n is in client coordinates*/
 				POINT Point;
 				GetCursorPos(&Point);
 				ScreenToClient(hwnd_frame, &Point);
 				pb::ballset(last_mouse_x - Point.x, Point.y - last_mouse_y);
-					Point = POINT{last_mouse_x, last_mouse_y};
+				Point = POINT{ last_mouse_x, last_mouse_y };
 				ClientToScreen(hwnd_frame, &Point);
 				SetCursorPos(Point.x, Point.y);
 			}
-			}
+
 			if (!single_step)
 			{
-				now = timeGetTime();
+				auto frameStart = timeGetTime();
-				if (no_time_loss)
+				auto dt = frameDuration;
-				{
+				if (!no_time_loss)
-					then = now;
-					no_time_loss = 0;
-				}
-
-				if (now == then)
-				{
-					Sleep(8u);
-				}
-				else
-				{
-					auto dt = now - then;
 					pb::frame(dt);
+				else
+					no_time_loss = 0;
 
 				if (DispGRhistory)
 				{
@@ -303,7 +295,7 @@ int winmain::WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLi
 
 					gdrv::ScrollBitmapHorizontal(&gfr_display, -1);
 
-						auto target = 8.0f;
+					float target = TargetFrameTime;
 					auto scale = height / target / 2;
 					gdrv::fill_bitmap(&gfr_display, 1, height, width - 1, 0, 0); // Background
 
@@ -318,9 +310,17 @@ int winmain::WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLi
 					gdrv::blit(&gfr_display, 0, 0, render::vscreen.Width - width, 0, width, height);
 				}
 
+				auto updateEnd = timeGetTime();
+				auto sleepDuration = TargetFrameTime - (int)(updateEnd - frameStart) - sleepRemainder;
+
+				if (sleepDuration > 0)
+					Sleep(sleepDuration);
+
+				auto frameEnd = timeGetTime();
+				sleepRemainder = (frameEnd - updateEnd) - sleepDuration;
+				frameDuration = min(frameEnd - frameStart, TargetFrameTime * 2);
+
 				--someTimeCounter;
-					then = now;
-				}
 			}
 		}
 	}

SpaceCadetPinball/winmain.h

@@ -26,11 +26,14 @@ public:
 private:
 	static int return_value, bQuit, DispFrameRate, DispGRhistory, activated;
 	static int has_focus, mouse_down, last_mouse_x, last_mouse_y, no_time_loss;
-	static DWORD then, now;
 	static UINT iFrostUniqueMsg;
 	static gdrv_bitmap8 gfr_display;
 	static HCURSOR mouse_hsave;
 	static bool restart;
 
 	static HDC _BeginPaint(HWND hWnd, LPPAINTSTRUCT lpPaint);
+	static void ResetTimer()
+	{
+		timeEndPeriod(1u);
+	}
 };