Emscripten: Add compatible main loop

src/PowderToy.cpp

@@ -510,10 +510,7 @@ int main(int argc, char * argv[])
 			}
 		}
 
-		while (engine.Running())
-		{
-			EngineProcess();
-		}
+		MainLoop();
 	};
 
 	if (enableBluescreen)

src/PowderToySDL.h

@@ -26,6 +26,7 @@ extern bool mouseDown;
 extern bool calculatedInitialMouse;
 extern bool hasMouseMoved;
 
+void MainLoop();
 void EngineProcess();
 void StartTextInput();
 void StopTextInput();

src/PowderToySDLCommon.cpp

@@ -0,0 +1,10 @@
+#include "PowderToySDL.h"
+#include "gui/interface/Engine.h"
+
+void MainLoop()
+{
+	while (ui::Engine::Ref().Running())
+	{
+		EngineProcess();
+	}
+}

src/PowderToySDLEmscripten.cpp

@@ -0,0 +1,37 @@
+#include "PowderToySDL.h"
+#include "gui/interface/Engine.h"
+#include <emscripten.h>
+#include <iostream>
+
+static float lastFpsLimit;
+static void updateFpsLimit()
+{
+	lastFpsLimit = ui::Engine::Ref().FpsLimit;
+	if (lastFpsLimit == 60.0f) // TODO: rework FPS cap so 60.0 is not the default
+	{
+		emscripten_set_main_loop_timing(EM_TIMING_RAF, 1);
+		std::cerr << "implicit fps limit via vsync" << std::endl;
+	}
+	else
+	{
+		auto delay = int(1000.f / lastFpsLimit);
+		emscripten_set_main_loop_timing(EM_TIMING_SETTIMEOUT, delay);
+		std::cerr << "explicit fps limit: " << delay << "ms delays" << std::endl;
+	}
+}
+
+static void mainLoopBody()
+{
+	EngineProcess();
+	if (lastFpsLimit != ui::Engine::Ref().FpsLimit)
+	{
+		updateFpsLimit();
+	}
+}
+
+void MainLoop()
+{
+	emscripten_set_main_loop(mainLoopBody, 0, 0);
+	updateFpsLimit();
+	mainLoopBody();
+}

src/common/platform/Common.cpp

@@ -3,7 +3,6 @@
 #include "common/tpt-rand.h"
 #include "Config.h"
 #include <memory>
-#include <list>
 #include <cstring>
 #include <fstream>
 #include <iostream>
@@ -108,20 +107,4 @@ bool WriteFile(const std::vector<char> &fileData, ByteString filename)
 	}
 	return true;
 }
-
-std::list<ExitFunc> exitFuncs;
-
-void Atexit(ExitFunc exitFunc)
-{
-	exitFuncs.push_front(exitFunc);
-}
-
-void Exit(int code)
-{
-	for (auto exitFunc : exitFuncs)
-	{
-		exitFunc();
-	}
-	exit(code);
-}
 }

src/common/platform/Emscripten.cpp

@@ -29,4 +29,12 @@ bool Install()
 {
 	return false;
 }
+
+void Atexit(ExitFunc exitFunc)
+{
+}
+
+void Exit(int code)
+{
+}
 }

src/common/platform/ExitCommon.cpp

@@ -0,0 +1,22 @@
+#include "Platform.h"
+#include <cstdlib>
+#include <list>
+
+namespace Platform
+{
+std::list<ExitFunc> exitFuncs;
+
+void Atexit(ExitFunc exitFunc)
+{
+	exitFuncs.push_front(exitFunc);
+}
+
+void Exit(int code)
+{
+	for (auto exitFunc : exitFuncs)
+	{
+		exitFunc();
+	}
+	exit(code);
+}
+}

src/common/platform/meson.build

@@ -10,18 +10,21 @@ if host_platform == 'windows'
 	path_sep_char = '\\\\'
 	common_files += files(
 		'Windows.cpp',
+		'ExitCommon.cpp',
 	)
 elif host_platform == 'darwin'
 	can_install_enforce_no = true
 	common_files += files(
 		'Darwin.cpp',
 		'Posix.cpp',
+		'ExitCommon.cpp',
 	)
 elif host_platform == 'android'
 	can_install_enforce_no = true
 	common_files += files(
 		'Android.cpp',
 		'Posix.cpp',
+		'ExitCommon.cpp',
 	)
 elif host_platform == 'emscripten'
 	use_bluescreen = false
@@ -36,12 +39,14 @@ elif host_platform == 'linux'
 	common_files += files(
 		'Linux.cpp',
 		'Posix.cpp',
+		'ExitCommon.cpp',
 	)
 else
 	can_install_enforce_no = true
 	common_files += files(
 		'Null.cpp',
 		'Posix.cpp',
+		'ExitCommon.cpp',
 	)
 endif
 conf_data.set('SET_WINDOW_ICON', set_window_icon ? 'true' : 'false')

src/meson.build

@@ -46,6 +46,15 @@ powder_files = files(
 	'lua/TPTScriptInterface.cpp',
 	'lua/TPTSTypes.cpp',
 )
+if host_platform == 'emscripten'
+	powder_files += files(
+		'PowderToySDLEmscripten.cpp',
+	)
+else
+	powder_files += files(
+		'PowderToySDLCommon.cpp',
+	)
+endif
 if is_x86
 	powder_files += files('X86KillDenormals.cpp')
 endif