SceneCaptureRendering.cpp

void FScene::UpdateSceneCaptureContents(USceneCaptureComponent2D* CaptureComponent)
{
	check(CaptureComponent);

	if (CaptureComponent->TextureTarget)
	{
		// Only ensure motion blur cache is up to date when doing USceneCaptureComponent2D::CaptureScene(),
		// but only when bAlwaysPersistRenderingState == true for backward compatibility.
		if (!CaptureComponent->bCaptureEveryFrame && CaptureComponent->bAlwaysPersistRenderingState)
		{
			// We assume the world is not paused since the CaptureScene() has manually been called.
			EnsureMotionBlurCacheIsUpToDate(/* bWorldIsPaused = */ false);
		}

		FTransform Transform = CaptureComponent->GetComponentToWorld();
		FVector ViewLocation = Transform.GetTranslation();

		// Remove the translation from Transform because we only need rotation.
		Transform.SetTranslation(FVector::ZeroVector);
		Transform.SetScale3D(FVector::OneVector);
		FMatrix ViewRotationMatrix = Transform.ToInverseMatrixWithScale();

		// swap axis st. x=z,y=x,z=y (unreal coord space) so that z is up
		ViewRotationMatrix = ViewRotationMatrix * FMatrix(
			FPlane(0, 0, 1, 0),
			FPlane(1, 0, 0, 0),
			FPlane(0, 1, 0, 0),
			FPlane(0, 0, 0, 1));
		const float FOV = CaptureComponent->FOVAngle * (float)PI / 360.0f;
		FIntPoint CaptureSize(CaptureComponent->TextureTarget->GetSurfaceWidth(), CaptureComponent->TextureTarget->GetSurfaceHeight());

		FMatrix ProjectionMatrix;
		if (CaptureComponent->bUseCustomProjectionMatrix)
		{
			ProjectionMatrix = CaptureComponent->CustomProjectionMatrix;
		}
		else
		{
			BuildProjectionMatrix(CaptureSize, CaptureComponent->ProjectionType, FOV, CaptureComponent->OrthoWidth, ProjectionMatrix);
		}

		const bool bUseSceneColorTexture = CaptureComponent->CaptureSource != SCS_FinalColorLDR;

		FSceneRenderer* SceneRenderer = CreateSceneRendererForSceneCapture(
			this, 
			CaptureComponent, 
			CaptureComponent->TextureTarget->GameThread_GetRenderTargetResource(), 
			CaptureSize, 
			ViewRotationMatrix, 
			ViewLocation, 
			ProjectionMatrix, 
			CaptureComponent->MaxViewDistanceOverride, 
			bUseSceneColorTexture, 
			false, 
			&CaptureComponent->PostProcessSettings, 
			CaptureComponent->PostProcessBlendWeight,
			CaptureComponent->GetViewOwner());

		SceneRenderer->ViewFamily.SceneCaptureSource = CaptureComponent->CaptureSource;
		SceneRenderer->ViewFamily.SceneCaptureCompositeMode = CaptureComponent->CompositeMode;

		{
			FPlane ClipPlane = FPlane(CaptureComponent->ClipPlaneBase, CaptureComponent->ClipPlaneNormal.GetSafeNormal());

			for (FSceneView& View : SceneRenderer->Views)
			{
				View.bCameraCut = CaptureComponent->bCameraCutThisFrame;

				if (CaptureComponent->bEnableClipPlane)
				{
					View.GlobalClippingPlane = ClipPlane;
					// Jitter can't be removed completely due to the clipping plane
					View.bAllowTemporalJitter = false;
				}
			}
		}

		// Reset scene capture's camera cut.
		CaptureComponent->bCameraCutThisFrame = false;

		FTextureRenderTargetResource* TextureRenderTarget = CaptureComponent->TextureTarget->GameThread_GetRenderTargetResource();
		const FName OwnerName = CaptureComponent->GetOwner() ? CaptureComponent->GetOwner()->GetFName() : NAME_None;
		ENQUEUE_RENDER_COMMAND(CaptureCommand)(
			[SceneRenderer, TextureRenderTarget, OwnerName](FRHICommandListImmediate& RHICmdList)
			{
				UpdateSceneCaptureContent_RenderThread(RHICmdList, SceneRenderer, TextureRenderTarget, TextureRenderTarget, OwnerName, FResolveParams());
			}
		);
	}
}