PostProcessMotionBlur.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
/*=============================================================================
    PostProcessMotionBlur.h: Post process MotionBlur implementation.
=============================================================================*/
 
#pragma once
 
#include "ScreenPass.h"
#include "TranslucentRendering.h"
#include "PostProcess/LensDistortion.h"
 
 
// Returns whether motion blur is enabled for the requested view.
bool IsMotionBlurEnabled(const FViewInfo& View);
 
// Returns whether visualization of motion blur is enabled for the requested view.
bool IsVisualizeMotionBlurEnabled(const FViewInfo& View);
 
// The quality level of the motion blur pass.
enum class EMotionBlurQuality : uint32
{
    Low,
    Medium,
    High,
    VeryHigh,
    MAX
};
 
enum class EMotionBlurFilter : uint32
{
    Unified,
    Separable
};
 
// Returns whether motion blur also want half res input the scene color's MIP1.
bool DoesMotionBlurNeedsHalfResInput();
 
// Returns the global setting for motion blur quality.
EMotionBlurQuality GetMotionBlurQuality();
 
// Returns the global setting for motion blur filter.
EMotionBlurFilter GetMotionBlurFilter();
 
// Number of simultaneous direction motion blur can blur per tiles.
int32 GetMotionBlurDirections();
 
// Shader parameters for MotionBlurVelocityFlatten.ush when another pass can also generate the FVelocityFlattenTextures
BEGIN_SHADER_PARAMETER_STRUCT(FVelocityFlattenParameters, )
    SHADER_PARAMETER(FVector2f, VelocityScale)
    SHADER_PARAMETER(float, VelocityMax)
END_SHADER_PARAMETER_STRUCT()
 
FVelocityFlattenParameters GetVelocityFlattenParameters(const FViewInfo& View);
 
// Textures generated by the velocity flattening pass.
struct FVelocityFlattenTextures
{
    static constexpr int32 kMaxVelocityTileTextureCount = 2;
    static constexpr int32 kTileSize = 16;
 
    FScreenPassTexture VelocityFlatten;
    FScreenPassTexture VelocityTileArray;
 
    bool IsValid() const
    {
        return VelocityFlatten.IsValid() && VelocityTileArray.IsValid();
    }
 
    // returns whether FVelocityFlattenTextures can be generated in external system.
    static bool AllowExternal(const FViewInfo& View);
};
 
struct FMotionBlurInputs
{
    bool bOutputHalfRes = false;
    bool bOutputQuarterRes = false;
 
    // [Optional] Render to the specified output. If invalid, a new texture is created and returned.
    FScreenPassRenderTarget OverrideOutput;
 
    // [Required] The input scene color and view rect.
    FScreenPassTextureSlice SceneColor;
 
    // [Required] The input scene depth and view rect.
    FScreenPassTexture SceneDepth;
 
    // [Required] The input scene velocity and view rect.
    FScreenPassTexture SceneVelocity;
 
    // [Optional] The separate translucency buffer to be composited after motion blur
    FTranslucencyPassResources PostMotionBlurTranslucency;
 
    // [Required] Quality to use when processing motion blur.
    EMotionBlurQuality Quality = EMotionBlurQuality::VeryHigh;
 
    // [Required] Filter to use when processing motion blur.
    EMotionBlurFilter Filter = EMotionBlurFilter::Separable;
 
    // [Optional] the velocity flatten is can be generated by a earlier pass.
    FVelocityFlattenTextures VelocityFlattenTextures;
 
    // [Optional] Lens distortion applied on the scene color.
    FLensDistortionLUT LensDistortionLUT;
};
 
struct FMotionBlurOutputs
{
    FScreenPassTextureSlice FullRes;
    FScreenPassTexture HalfRes;
    FScreenPassTexture QuarterRes;
};
 
FMotionBlurOutputs AddMotionBlurPass(FRDGBuilder& GraphBuilder, const FViewInfo& View, const FMotionBlurInputs& Inputs);
FScreenPassTextureSlice AddVisualizeMotionBlurPass(FRDGBuilder& GraphBuilder, const FViewInfo& View, const FMotionBlurInputs& Inputs);