Direct3D11: Reduce FPS instead of crashing when minimised

src/Graphics_D3D11.c

@@ -942,6 +942,13 @@ void Gfx_EndFrame(void) {
 	// https://docs.microsoft.com/en-us/windows/win32/api/dxgi/nf-dxgi-idxgiswapchain-present
 	// gfx_vsync happens to match SyncInterval parameter
 	HRESULT hr = IDXGISwapChain_Present(swapchain, gfx_vsync, 0);
+
+	// run at reduced FPS when minimised
+	if (hr == DXGI_STATUS_OCCLUDED) {
+		TickReducedPerformance(); return;
+	}
+
+	EndReducedPerformance();
 	if (hr) Logger_Abort2(hr, "Failed to swap buffers");
 }
 

src/Menus.c

@@ -3691,7 +3691,7 @@ static const struct ScreenVTABLE TexPackOverlay_VTABLE = {
 void TexPackOverlay_Show(const cc_string* url) {
 	struct TexPackOverlay* s = &TexPackOverlay;
 	s->grabsInput = true;
-	/* Too easy to accidentally ESC this important dialog*/
+	/* Too easy to accidentally ESC this important dialog */
 	/* s->closable= true; */
 	s->VTABLE     = &TexPackOverlay_VTABLE;
 	

src/_GraphicsBase.h

@@ -91,6 +91,21 @@ void Gfx_RecreateContext(void) {
 	Event_RaiseVoid(&GfxEvents.ContextRecreated);
 }
 
+cc_bool reducedPerformance;
+static void TickReducedPerformance(void) {
+	Thread_Sleep(100); /* 10 FPS */
+
+	if (reducedPerformance) return;
+	reducedPerformance = true; /* TODO: also log a message in-game? */
+	Platform_LogConst("Entering reduced performance mode");
+}
+
+static void EndReducedPerformance(void) {
+	if (!reducedPerformance) return;
+	reducedPerformance = false;
+	Platform_LogConst("Exited reduced performance mode");
+}
+
 
 void Gfx_RecreateDynamicVb(GfxResourceID* vb, VertexFormat fmt, int maxVertices) {
 	Gfx_DeleteDynamicVb(vb);