Add NeedsRenderThread property to GraphicsContext

Common/GraphicsContext.h

@@ -29,6 +29,9 @@ public:
 	// Needs casting to the appropriate type, unfortunately. Should find a better solution..
 	virtual void *GetAPIContext() { return nullptr; }
 
+	// OpenGL returns true here.
+	virtual bool NeedsRenderThread() const { return false; }
+
 	// Called from the render thread from threaded backends.
 	virtual void ThreadStart() {}
 	virtual bool ThreadFrame(bool waitIfEmpty) { return true; }   // waitIfEmpty should normally be true, except in exit scenarios.
@@ -41,6 +44,8 @@ public:
 	virtual Draw::DrawContext *GetDrawContext() = 0;
 
 	void ThreadFrameUntilCondition(std::function<bool()> conditionStopped) {
+		_dbg_assert_(NeedsRenderThread());
+
 		bool exitOnEmpty = false;
 
 		INFO_LOG(Log::System, "Executing graphicsContext->ThreadFrame to clear buffers");

Core/EmuThread.cpp

@@ -74,23 +74,24 @@ std::thread EmuThread_Start(GraphicsContext *graphicsContext, std::function<void
 }
 
 void EmuThread_Join(GraphicsContext *graphicsContext, std::thread &emuThread) {
-	_dbg_assert_(emuThread.joinable());
 	const EmuThreadState state = g_emuThreadState;
 	if (state != EmuThreadState::QUIT_REQUESTED &&
 		state != EmuThreadState::STOPPED) {
 		g_emuThreadState = EmuThreadState::QUIT_REQUESTED;
 	}
-	graphicsContext->ThreadFrameUntilCondition([] {
-		// Need to keep eating frames to allow the EmuThread to exit correctly.
-		return g_emuThreadState == EmuThreadState::STOPPED;
-	});
+	_dbg_assert_(emuThread.joinable());
+	if (graphicsContext->NeedsRenderThread()) {
+		graphicsContext->ThreadFrameUntilCondition([] {
+			// Need to keep eating frames to allow the EmuThread to exit correctly.
+			return g_emuThreadState == EmuThreadState::STOPPED;
+		});
+	}
 	emuThread.join();
 	emuThread = std::thread();
 }
 
 void MainThreadFunc(GraphicsContext *graphicsContext, std::function<void()> postFrame) {
-	const bool useEmuThread = g_Config.iGPUBackend == (int)GPUBackend::OPENGL;
-	if (useEmuThread) {
+	if (graphicsContext->NeedsRenderThread()) {
 		SetCurrentThreadName("RenderThread");
 		// This is now the render thread, and will spawn the emu thread below.
 
@@ -139,7 +140,6 @@ void MainThreadFunc(GraphicsContext *graphicsContext, std::function<void()> post
 		g_inLoop = true;
 
 		graphicsContext->ThreadStart();
-
 		while (GetUIState() != UISTATE_EXIT) {
 			// We're here again, so the game quit.  Restart Run() which controls the UI.
 			// This way they can load a new game.
@@ -158,7 +158,6 @@ void MainThreadFunc(GraphicsContext *graphicsContext, std::function<void()> post
 
 		graphicsContext->ThreadEnd();
 		graphicsContext->ShutdownFromRenderThread();
-
 	}
 
 	graphicsContext->Shutdown();

Qt/QtMain.h

@@ -65,6 +65,8 @@ public:
 		renderManager_ = nullptr;
 	}
 
+	bool NeedsRenderThread() const override { return true; }
+
 	void Shutdown() override {}
 	void Resize() override {}
 

SDL/SDLGLGraphicsContext.h

@@ -12,6 +12,8 @@ public:
 	// Returns 0 on success.
 	int Init(SDL_Window *&window, int x, int y, int w, int h, int mode, std::string *error_message, int force_gl_version);
 
+	bool NeedsRenderThread() const override { return true; }
+
 	bool InitFromRenderThread(std::string *errorMessage) override;
 
 	void Shutdown() override {}

Windows/GPU/WindowsGLContext.h

@@ -13,6 +13,8 @@ class WindowsGLContext : public WindowsGraphicsContext {
 public:
 	bool Init(HINSTANCE hInst, HWND window, std::string *error_message) override;
 
+	bool NeedsRenderThread() const override { return true; }
+
 	bool InitFromRenderThread(std::string *errorMessage) override;
 	void ShutdownFromRenderThread() override;
 

android/jni/AndroidJavaGLContext.h

@@ -9,6 +9,8 @@ public:
 	AndroidJavaEGLGraphicsContext();
 	~AndroidJavaEGLGraphicsContext() override { delete draw_; }
 
+	bool NeedsRenderThread() const override { return true; }
+
 	// This performs the actual initialization,
 	bool InitFromRenderThread(ANativeWindow *wnd, int desiredBackbufferSizeX, int desiredBackbufferSizeY, int backbufferFormat, int androidVersion) override;
 

ios/ViewController.mm

@@ -55,6 +55,7 @@ public:
 	~IOSGLESContext() {
 		delete draw_;
 	}
+	bool NeedsRenderThread() const override { return true; }
 	Draw::DrawContext *GetDrawContext() override {
 		return draw_;
 	}

libretro/LibretroGLContext.h

@@ -16,6 +16,8 @@ public:
 		hw_render_.bottom_left_origin = true;
 	}
 
+   bool NeedsRenderThread() const override { return true; }
+
 	bool Init() override;
 	void CreateDrawContext() override;
 	void DestroyDrawContext() override;

libretro/LibretroGLCoreContext.h

@@ -7,10 +7,10 @@
 class LibretroGLCoreContext : public LibretroHWRenderContext {
 public:
 	LibretroGLCoreContext()
-		: LibretroHWRenderContext(RETRO_HW_CONTEXT_OPENGL_CORE, 3, 1)
-	{
+		: LibretroHWRenderContext(RETRO_HW_CONTEXT_OPENGL_CORE, 3, 1) {
 		hw_render_.bottom_left_origin = true;
 	}
+   bool NeedsRenderThread() const override { return true; }
 
 	bool Init() override;
 	void CreateDrawContext() override;