/** 
* Renders the view family. 
*/
void FDeferredShadingSceneRenderer::Render()
{
	if(!ViewFamily.EngineShowFlags.Rendering)
	{
		return;
	}

	SCOPED_DRAW_EVENT(Scene,DEC_SCENE_ITEMS);

	// Initialize global system textures (pass-through if already initialized).
	GSystemTextures.InitializeTextures();

	// Allocate the maximum scene render target space for the current view family.
	GSceneRenderTargets.Allocate(ViewFamily);

	// Find the visible primitives.
	InitViews();

	const bool bIsWireframe = ViewFamily.EngineShowFlags.Wireframe;

	static const auto ClearMethodCVar = IConsoleManager::Get().FindTConsoleVariableDataInt(TEXT("r.ClearSceneMethod"));
	bool bRequiresRHIClear = true;
	bool bRequiresFarZQuadClear = false;

	if (ClearMethodCVar)
	{
		switch (ClearMethodCVar->GetValueOnRenderThread())
		{
		case 0: // No clear
			{
				bRequiresRHIClear = false;
				bRequiresFarZQuadClear = false;
				break;
			}
		
		case 1: // RHIClear
			{
				bRequiresRHIClear = true;
				bRequiresFarZQuadClear = false;
				break;
			}

		case 2: // Clear using far-z quad
			{
				bRequiresFarZQuadClear = true;
				bRequiresRHIClear = false;
				break;
			}
		}
	}

	// Always perform a full buffer clear for wireframe, shader complexity view mode, and stationary light overlap viewmode.
	if (bIsWireframe || ViewFamily.EngineShowFlags.ShaderComplexity || ViewFamily.EngineShowFlags.StationaryLightOverlap)
	{
		bRequiresRHIClear = true;
	}

	// force using occ queries for wireframe if rendering is parented or frozen in the first view
	check(Views.Num());
	#if (UE_BUILD_SHIPPING || UE_BUILD_TEST)
		const bool bIsViewFrozen = false;
		const bool bHasViewParent = false;
	#else
		const bool bIsViewFrozen = Views[0].State && ((FSceneViewState*)Views[0].State)->bIsFrozen;
		const bool bHasViewParent = Views[0].State && ((FSceneViewState*)Views[0].State)->HasViewParent();
	#endif
	const bool bIsOcclusionTesting = DoOcclusionQueries() && (!bIsWireframe || bIsViewFrozen || bHasViewParent);

	// Dynamic vertex and index buffers need to be committed before rendering.
	FGlobalDynamicVertexBuffer::Get().Commit();
	FGlobalDynamicIndexBuffer::Get().Commit();

	// Notify the FX system that the scene is about to be rendered.
	if (Scene->FXSystem)
	{
		Scene->FXSystem->PreRender();
	}

	// Draw the scene pre-pass / early z pass, populating the scene depth buffer and HiZ
	RenderPrePass();
	
	// Clear scene color buffer if necessary.
	if ( bRequiresRHIClear )
	{
		ClearView();

		// Only clear once.
		bRequiresRHIClear = false;
	}

	// Clear LPVs for all views
	if ( IsFeatureLevelSupported(GRHIShaderPlatform, ERHIFeatureLevel::SM5) )
	{
		ClearLPVs();
	}

	// only temporarily available after early z pass and until base pass
	check(!GSceneRenderTargets.DBufferA);
	check(!GSceneRenderTargets.DBufferB);
	check(!GSceneRenderTargets.DBufferC);

	if(IsDBufferEnabled())
	{
		GSceneRenderTargets.ResolveSceneDepthTexture();

		// Resolve the scene depth to an auxiliary texture when SM3/SM4 is in use. This needs to happen so the auxiliary texture can be bound as a shader parameter
		// while the primary scene depth texture can be bound as the target. Simultaneously binding a single DepthStencil resource as a parameter and target
		// is unsupported in d3d feature level 10.
		if(!(GRHIFeatureLevel >= ERHIFeatureLevel::SM5) && GRHIFeatureLevel >= ERHIFeatureLevel::SM4)
		{
			GSceneRenderTargets.ResolveSceneDepthToAuxiliaryTexture();
		}

		// e.g. ambient cubemaps, ambient occlusion, deferred decals
		for(int32 ViewIndex = 0;ViewIndex < Views.Num();ViewIndex++)
		{	
			SCOPED_CONDITIONAL_DRAW_EVENTF(EventView,Views.Num() > 1, DEC_SCENE_ITEMS, TEXT("View%d"), ViewIndex);
			GCompositionLighting.ProcessBeforeBasePass(Views[ViewIndex]);
		}
	}

	if(bIsWireframe && FDeferredShadingSceneRenderer::ShouldCompositeEditorPrimitives(Views[0]))
	{
		// In Editor we want wire frame view modes to be MSAA for better quality. Resolve will be done with EditorPrimitives
		RHISetRenderTarget(GSceneRenderTargets.GetEditorPrimitivesColor(), GSceneRenderTargets.GetEditorPrimitivesDepth());
		RHIClear(true, FLinearColor(0, 0, 0, 0), true, 0.0f, false, 0, FIntRect());
	}
	else
	{
		// Begin rendering to scene color
		GSceneRenderTargets.BeginRenderingSceneColor(true);
	}

	RenderBasePass();

	if(ViewFamily.EngineShowFlags.VisualizeLightCulling)
	{
		// clear out emissive and baked lighting (not too efficient but simple and only needed for this debug view)
		GSceneRenderTargets.BeginRenderingSceneColor(false);
		RHIClear(true, FLinearColor(0, 0, 0, 0), false, 0, false, 0, FIntRect());
	}

	GSceneRenderTargets.DBufferA.SafeRelease();
	GSceneRenderTargets.DBufferB.SafeRelease();
	GSceneRenderTargets.DBufferC.SafeRelease();

	// only temporarily available after early z pass and until base pass
	check(!GSceneRenderTargets.DBufferA);
	check(!GSceneRenderTargets.DBufferB);
	check(!GSceneRenderTargets.DBufferC);

	if (bRequiresFarZQuadClear)
	{
		// Clears view by drawing quad at maximum Z
		// TODO: if all the platforms have fast color clears, we can replace this with an RHIClear.
		ClearGBufferAtMaxZ();

		bRequiresFarZQuadClear = false;
	}
	
	GSceneRenderTargets.ResolveSceneColor(FResolveRect(0, 0, ViewFamily.FamilySizeX, ViewFamily.FamilySizeY));
	GSceneRenderTargets.ResolveSceneDepthTexture();

	// Resolve the scene depth to an auxiliary texture when SM3/SM4 is in use. This needs to happen so the auxiliary texture can be bound as a shader parameter
	// while the primary scene depth texture can be bound as the target. Simultaneously binding a single DepthStencil resource as a parameter and target
	// is unsupported in d3d feature level 10.
	if(!GSupportsDepthFetchDuringDepthTest)
	{
		GSceneRenderTargets.ResolveSceneDepthToAuxiliaryTexture();
	}
	
	RenderCustomDepthPass();

	// Notify the FX system that opaque primitives have been rendered and we now have a valid depth buffer.
	if (Scene->FXSystem && Views.IsValidIndex(0))
	{
		Scene->FXSystem->PostRenderOpaque(
			Views.GetTypedData(),
			GSceneRenderTargets.GetSceneDepthTexture(),
			GSceneRenderTargets.GetGBufferATexture()
			);
	}

	// Update the quarter-sized depth buffer with the current contents of the scene depth texture.
	// This needs to happen before occlusion tests, which makes use of the small depth buffer.
	UpdateDownsampledDepthSurface();

	// Issue occlusion queries
	// This is done after the downsampled depth buffer is created so that it can be used for issuing queries
	if ( bIsOcclusionTesting )
	{
		BeginOcclusionTests();
	}
	
	// Render lighting.
	if (ViewFamily.EngineShowFlags.Lighting
		&& GRHIFeatureLevel >= ERHIFeatureLevel::SM4
		&& ViewFamily.EngineShowFlags.DeferredLighting
		)
	{
		// Pre-lighting composition lighting stage
		// e.g. deferred decals, blurred GBuffer
		for(int32 ViewIndex = 0;ViewIndex < Views.Num();ViewIndex++)
		{	
			SCOPED_CONDITIONAL_DRAW_EVENTF(EventView,Views.Num() > 1, DEC_SCENE_ITEMS, TEXT("View%d"), ViewIndex);
			GCompositionLighting.ProcessAfterBasePass(Views[ViewIndex]);
		}
		
		// Clear the translucent lighting volumes before we accumulate
		ClearTranslucentVolumeLighting();

		RenderLights();

		InjectAmbientCubemapTranslucentVolumeLighting();

		CompositeIndirectTranslucentVolumeLighting();

		// Filter the translucency lighting volume now that it is complete
		FilterTranslucentVolumeLighting();

		// Clear LPVs for all views
		if ( IsFeatureLevelSupported(GRHIShaderPlatform, ERHIFeatureLevel::SM5) )
		{
			PropagateLPVs();
		}

		// Render reflections that only operate on opaque pixels
		RenderDeferredReflections();

		// Post-lighting composition lighting stage
		// e.g. ambient cubemaps, ambient occlusion, LPV indirect
		for(int32 ViewIndex = 0; ViewIndex < Views.Num(); ++ViewIndex)
		{	
			SCOPED_CONDITIONAL_DRAW_EVENTF(EventView,Views.Num() > 1, DEC_SCENE_ITEMS, TEXT("View%d"), ViewIndex);
			GCompositionLighting.ProcessLighting(Views[ViewIndex]);
		}
	}

	if( ViewFamily.EngineShowFlags.StationaryLightOverlap &&
		GRHIFeatureLevel >= ERHIFeatureLevel::SM4)
	{
		RenderStationaryLightOverlap();
	}

	FLightShaftsOutput LightShaftOutput;

	// Draw Lightshafts
	if (ViewFamily.EngineShowFlags.LightShafts)
	{
		LightShaftOutput = RenderLightShaftOcclusion();
	}

	// Draw atmosphere
	if(ShouldRenderAtmosphere(ViewFamily))
	{
		if (Scene->AtmosphericFog)
		{
			// Update RenderFlag based on LightShaftTexture is valid or not
			if (LightShaftOutput.bRendered)
			{
				Scene->AtmosphericFog->RenderFlag &= EAtmosphereRenderFlag::E_LightShaftMask;
			}
			else
			{
				Scene->AtmosphericFog->RenderFlag |= EAtmosphereRenderFlag::E_DisableLightShaft;
			}
#if WITH_EDITOR
			if (Scene->bIsEditorScene)
			{
				// Precompute Atmospheric Textures
				Scene->AtmosphericFog->PrecomputeTextures(Views.GetTypedData(), &ViewFamily);
			}
#endif
			RenderAtmosphere(LightShaftOutput);
		}
	}

	// Draw fog.
	if(ShouldRenderFog(ViewFamily))
	{
		RenderFog(LightShaftOutput);
	}

	// No longer needed, release
	LightShaftOutput.LightShaftOcclusion = NULL;

	// Draw translucency.
	if(ViewFamily.EngineShowFlags.Translucency)
	{
		SCOPE_CYCLE_COUNTER(STAT_TranslucencyDrawTime);

		if(ViewFamily.EngineShowFlags.Refraction)
		{
			// to apply refraction effect by distorting the scene color
			RenderDistortion();
		}
		RenderTranslucency();
	}

	if (ViewFamily.EngineShowFlags.LightShafts)
	{
		RenderLightShaftBloom();
	}

	// Resolve the scene color for post processing.
	GSceneRenderTargets.ResolveSceneColor(FResolveRect(0, 0, ViewFamily.FamilySizeX, ViewFamily.FamilySizeY));

#if !(UE_BUILD_SHIPPING || UE_BUILD_TEST)
	if(CVarTestUIBlur.GetValueOnRenderThread() > 0)
	{
		Views[0].UIBlurOverrideRectangles.Add(FIntRect(20, 20, 400, 400));
	}
#endif

	// Finish rendering for each view.
	if(ViewFamily.bResolveScene)
	{
		SCOPED_DRAW_EVENT(FinishRendering, DEC_SCENE_ITEMS);
		SCOPE_CYCLE_COUNTER(STAT_FinishRenderViewTargetTime);
		for(int32 ViewIndex = 0;ViewIndex < Views.Num();ViewIndex++)
		{	
			SCOPED_CONDITIONAL_DRAW_EVENTF(EventView, Views.Num() > 1, DEC_SCENE_ITEMS, TEXT("View%d"), ViewIndex);
			FinishRenderViewTarget(&Views[ViewIndex], ViewIndex == (Views.Num() - 1));
		}
	}

	RenderFinish();
}
/** 
* Renders the view family. 
*/
void FForwardShadingSceneRenderer::Render(FRHICommandListImmediate& RHICmdList)
{
	if(!ViewFamily.EngineShowFlags.Rendering)
	{
		return;
	}

	auto FeatureLevel = ViewFamily.GetFeatureLevel();

	// Initialize global system textures (pass-through if already initialized).
	GSystemTextures.InitializeTextures(RHICmdList, FeatureLevel);

	// Allocate the maximum scene render target space for the current view family.
	GSceneRenderTargets.Allocate(ViewFamily);

	// Find the visible primitives.
	InitViews(RHICmdList);
	
	RenderShadowDepthMaps(RHICmdList);

	// Notify the FX system that the scene is about to be rendered.
	if (Scene->FXSystem)
	{
		Scene->FXSystem->PreRender(RHICmdList);
	}

	GRenderTargetPool.VisualizeTexture.OnStartFrame(Views[0]);

	// Dynamic vertex and index buffers need to be committed before rendering.
	FGlobalDynamicVertexBuffer::Get().Commit();
	FGlobalDynamicIndexBuffer::Get().Commit();

	// This might eventually be a problem with multiple views.
	// Using only view 0 to check to do on-chip transform of alpha.
	FViewInfo& View = Views[0];

	const bool bGammaSpace = !IsMobileHDR();
	const bool bRequiresUpscale = ((uint32)ViewFamily.RenderTarget->GetSizeXY().X > ViewFamily.FamilySizeX || (uint32)ViewFamily.RenderTarget->GetSizeXY().Y > ViewFamily.FamilySizeY);
	const bool bRenderToScene = bRequiresUpscale || FSceneRenderer::ShouldCompositeEditorPrimitives(View);

	if (bGammaSpace && !bRenderToScene)
	{
		SetRenderTarget(RHICmdList, ViewFamily.RenderTarget->GetRenderTargetTexture(), GSceneRenderTargets.GetSceneDepthTexture(), ESimpleRenderTargetMode::EClearToDefault);
	}
	else
	{
		// Begin rendering to scene color
		GSceneRenderTargets.BeginRenderingSceneColor(RHICmdList, ESimpleRenderTargetMode::EClearToDefault);
	}

	if (GIsEditor)
	{
		RHICmdList.Clear(true, Views[0].BackgroundColor, false, 0, false, 0, FIntRect());
	}

	RenderForwardShadingBasePass(RHICmdList);

	// Make a copy of the scene depth if the current hardware doesn't support reading and writing to the same depth buffer
	GSceneRenderTargets.ResolveSceneDepthToAuxiliaryTexture(RHICmdList);

	// Notify the FX system that opaque primitives have been rendered.
	if (Scene->FXSystem)
	{
		Scene->FXSystem->PostRenderOpaque(RHICmdList);
	}

	// Draw translucency.
	if (ViewFamily.EngineShowFlags.Translucency)
	{
		SCOPE_CYCLE_COUNTER(STAT_TranslucencyDrawTime);

		// Note: Forward pass has no SeparateTranslucency, so refraction effect order with Transluency is different.
		// Having the distortion applied between two different translucency passes would make it consistent with the deferred pass.
		// This is not done yet.

		if (ViewFamily.EngineShowFlags.Refraction)
		{
			// to apply refraction effect by distorting the scene color
			RenderDistortion(RHICmdList);
		}
		RenderTranslucency(RHICmdList);
	}

	static const auto CVarMobileMSAA = IConsoleManager::Get().FindTConsoleVariableDataInt(TEXT("r.MobileMSAA"));
	bool bOnChipSunMask =
		GSupportsRenderTargetFormat_PF_FloatRGBA &&
		GSupportsShaderFramebufferFetch &&
		ViewFamily.EngineShowFlags.PostProcessing &&
		((View.bLightShaftUse) || (View.FinalPostProcessSettings.DepthOfFieldScale > 0.0) ||
		((ViewFamily.GetShaderPlatform() == SP_METAL) && (CVarMobileMSAA ? CVarMobileMSAA->GetValueOnAnyThread() > 1 : false))
		);

	if (!bGammaSpace && bOnChipSunMask)
	{
		// Convert alpha from depth to circle of confusion with sunshaft intensity.
		// This is done before resolve on hardware with framebuffer fetch.
		// This will break when PrePostSourceViewportSize is not full size.
		FIntPoint PrePostSourceViewportSize = GSceneRenderTargets.GetBufferSizeXY();

		FMemMark Mark(FMemStack::Get());
		FRenderingCompositePassContext CompositeContext(RHICmdList, View);

		FRenderingCompositePass* PostProcessSunMask = CompositeContext.Graph.RegisterPass(new(FMemStack::Get()) FRCPassPostProcessSunMaskES2(PrePostSourceViewportSize, true));
		CompositeContext.Root->AddDependency(FRenderingCompositeOutputRef(PostProcessSunMask));
		CompositeContext.Process(TEXT("OnChipAlphaTransform"));
	}

	if (!bGammaSpace || bRenderToScene)
	{
		// Resolve the scene color for post processing.
		GSceneRenderTargets.ResolveSceneColor(RHICmdList, FResolveRect(0, 0, ViewFamily.FamilySizeX, ViewFamily.FamilySizeY));

		// Drop depth and stencil before post processing to avoid export.
		RHICmdList.DiscardRenderTargets(true, true, 0);
	}

	if (!bGammaSpace)
	{
		// Finish rendering for each view, or the full stereo buffer if enabled
		if (ViewFamily.bResolveScene)
		{
			if (ViewFamily.EngineShowFlags.StereoRendering)
			{
				check(Views.Num() > 1);

				//@todo ES2 stereo post: until we get proper stereo postprocessing for ES2, process the stereo buffer as one view
				FIntPoint OriginalMax0 = Views[0].ViewRect.Max;
				Views[0].ViewRect.Max = Views[1].ViewRect.Max;
				GPostProcessing.ProcessES2(RHICmdList, Views[0], bOnChipSunMask);
				Views[0].ViewRect.Max = OriginalMax0;
			}
			else
			{
				SCOPED_DRAW_EVENT(RHICmdList, PostProcessing);
				SCOPE_CYCLE_COUNTER(STAT_FinishRenderViewTargetTime);
				for(int32 ViewIndex = 0;ViewIndex < Views.Num();ViewIndex++)
				{
					SCOPED_CONDITIONAL_DRAW_EVENTF(RHICmdList, EventView, Views.Num() > 1, TEXT("View%d"), ViewIndex);
					GPostProcessing.ProcessES2(RHICmdList, Views[ViewIndex], bOnChipSunMask);
				}
			}
		}
	}
	else if (bRenderToScene)
	{
		BasicPostProcess(RHICmdList, View, bRequiresUpscale, FSceneRenderer::ShouldCompositeEditorPrimitives(View));
	}
	RenderFinish(RHICmdList);
}