Android: Pause rendering while the app is paused (#14058)

src/client/game.cpp

@@ -4010,31 +4010,6 @@ void Game::updateFrame(ProfilerGraph *graph, RunStats *stats, f32 dtime,
 	*/
 	client->getParticleManager()->step(dtime);
 
-	/*
-		Fog
-	*/
-	if (m_cache_enable_fog) {
-		driver->setFog(
-				sky->getBgColor(),
-				video::EFT_FOG_LINEAR,
-				runData.fog_range * sky->getFogStart(),
-				runData.fog_range * 1.0,
-				0.01,
-				false, // pixel fog
-				true // range fog
-		);
-	} else {
-		driver->setFog(
-				sky->getBgColor(),
-				video::EFT_FOG_LINEAR,
-				100000 * BS,
-				110000 * BS,
-				0.01f,
-				false, // pixel fog
-				false // range fog
-		);
-	}
-
 	/*
 		Damage camera tilt
 	*/
@@ -4134,7 +4109,8 @@ void Game::updateFrame(ProfilerGraph *graph, RunStats *stats, f32 dtime,
 	/*
 		==================== Drawing begins ====================
 	*/
-	drawScene(graph, stats);
+	if (RenderingEngine::shouldRender())
+		drawScene(graph, stats);
 	/*
 		==================== End scene ====================
 	*/
@@ -4214,10 +4190,39 @@ void Game::updateShadows()
 
 void Game::drawScene(ProfilerGraph *graph, RunStats *stats)
 {
-	const video::SColor skycolor = this->sky->getSkyColor();
+	const video::SColor bg_color = this->sky->getBgColor();
+	const video::SColor sky_color = this->sky->getSkyColor();
 
+	/*
+		Fog
+	*/
+	if (this->m_cache_enable_fog) {
+		this->driver->setFog(
+				bg_color,
+				video::EFT_FOG_LINEAR,
+				this->runData.fog_range * this->sky->getFogStart(),
+				this->runData.fog_range * 1.0f,
+				0.01f,
+				false, // pixel fog
+				true // range fog
+		);
+	} else {
+		this->driver->setFog(
+				bg_color,
+				video::EFT_FOG_LINEAR,
+				100000 * BS,
+				110000 * BS,
+				0.01f,
+				false, // pixel fog
+				false // range fog
+		);
+	}
+
+	/*
+		Drawing
+	*/
 	TimeTaker tt_draw("Draw scene", nullptr, PRECISION_MICRO);
-	this->driver->beginScene(true, true, skycolor);
+	this->driver->beginScene(true, true, sky_color);
 
 	const LocalPlayer *player = this->client->getEnv().getLocalPlayer();
 	bool draw_wield_tool = (this->m_game_ui->m_flags.show_hud &&
@@ -4230,7 +4235,7 @@ void Game::drawScene(ProfilerGraph *graph, RunStats *stats)
 	if (this->isNoCrosshairAllowed())
 		draw_crosshair = false;
 #endif
-	this->m_rendering_engine->draw_scene(skycolor, this->m_game_ui->m_flags.show_hud,
+	this->m_rendering_engine->draw_scene(sky_color, this->m_game_ui->m_flags.show_hud,
 			this->m_game_ui->m_flags.show_minimap, draw_wield_tool, draw_crosshair);
 
 	/*

src/client/renderingengine.h

@@ -138,6 +138,17 @@ public:
 			const irr::core::dimension2d<u32> initial_screen_size,
 			const bool initial_window_maximized);
 
+	static bool shouldRender()
+	{
+		// On Android, pause rendering while the app is in background (generally not visible).
+		// Don't do this on desktop because windows can be partially visible.
+#ifdef __ANDROID__
+		return get_raw_device()->isWindowActive();
+#else
+		return true;
+#endif
+	};
+
 private:
 	v2u32 _getWindowSize() const;
 

src/gui/guiEngine.cpp

@@ -265,35 +265,36 @@ void GUIEngine::run()
 	f32 dtime = 0.0f;
 
 	while (m_rendering_engine->run() && (!m_startgame) && (!m_kill)) {
+		if (RenderingEngine::shouldRender()) {
+			// check if we need to update the "upper left corner"-text
+			if (text_height != g_fontengine->getTextHeight()) {
+				updateTopLeftTextSize();
+				text_height = g_fontengine->getTextHeight();
+			}
 
-		//check if we need to update the "upper left corner"-text
+			driver->beginScene(true, true, RenderingEngine::MENU_SKY_COLOR);
-		if (text_height != g_fontengine->getTextHeight()) {
+
-			updateTopLeftTextSize();
+			if (m_clouds_enabled)
-			text_height = g_fontengine->getTextHeight();
+			{
+				cloudPreProcess();
+				drawOverlay(driver);
+			}
+			else
+				drawBackground(driver);
+
+			drawFooter(driver);
+
+			m_rendering_engine->get_gui_env()->drawAll();
+
+			// The header *must* be drawn after the menu because it uses
+			// GUIFormspecMenu::getAbsoluteRect().
+			// The header *can* be drawn after the menu because it never intersects
+			// the menu.
+			drawHeader(driver);
+
+			driver->endScene();
 		}
 
-		driver->beginScene(true, true, RenderingEngine::MENU_SKY_COLOR);
-
-		if (m_clouds_enabled)
-		{
-			cloudPreProcess();
-			drawOverlay(driver);
-		}
-		else
-			drawBackground(driver);
-
-		drawFooter(driver);
-
-		m_rendering_engine->get_gui_env()->drawAll();
-
-		// The header *must* be drawn after the menu because it uses
-		// GUIFormspecMenu::getAbsoluteRect().
-		// The header *can* be drawn after the menu because it never intersects
-		// the menu.
-		drawHeader(driver);
-
-		driver->endScene();
-
 		IrrlichtDevice *device = m_rendering_engine->get_raw_device();
 
 		u32 frametime_min = 1000 / (device->isWindowFocused()