UE5 渲染源码学习 - 添加描边后处理 Shader

效果对比

添加描边 Shader：EdgePsShaders.usf

#include "../Common.ush"

Texture2D SceneColorTexture;
SamplerState SceneColorSampler;

void MainPS(
    noperspective float4 UVAndScreenPos : TEXCOORD0,
    float4 SvPosition : SV_POSITION,
    out float4 OutColor : SV_Target0)
{
    float2 UV = UVAndScreenPos.xy;
    float3 FinalColor = float3(0.0,0.0,0.0);
    const int edgeSize = 1;

    for(int x = -edgeSize; x<=edgeSize; ++x)
    {
        for(int y = -edgeSize; y <= edgeSize; ++y)
        {
            float2 SampleUV = UV + (float2(x,y) * View.BufferSizeAndInvSize.zw);
            float3 SampleColor = Texture2DSample(SceneColorTexture, SceneColorSampler, SampleUV).rgb;
            
            if(x == 0 && y == 0)
            {
                FinalColor += (8 * SampleColor);
            }
            else
            {
                FinalColor += (-1 * SampleColor);
            }
        }
    }

    FinalColor = dot(FinalColor, float3(0.299, 0.587, 0.114));
    OutColor = float4(FinalColor, 1.0);
}

添加 Renderer 以及 Shader 声明

DrawEdgePsRendering.h

#pragma once

#include "RenderGraphFwd.h"
#include "Engine/World.h"
#include "GlobalShader.h"
#include "PipelineStateCache.h"
#include "RHIStaticStates.h"
#include "SceneUtils.h"
#include "../SceneRendering.h"
#include "SceneInterface.h"
#include "ShaderParameterUtils.h"

void RenderEdgePs(FRDGBuilder& GraphBuilder, const FViewInfo& View, FRDGTextureRef InputColorTexture, FRDGTextureRef ViewTexture);

DrawEdgePsRendering.cpp

#include "DrawEdgePsRendering.h"
#include "GlobalShader.h"
#include "ShaderParameterStruct.h"
#include "Engine/World.h"
#include "PipelineStateCache.h"
#include "RHIStaticStates.h"
#include "SceneUtils.h"
#include "SceneInterface.h"
#include "ShaderParameterUtils.h"
#include "../SceneRendering.h"
#include "../Public/ScreenPass.h"

class FEdgePsPS : public FGlobalShader
{
public:
    DECLARE_SHADER_TYPE(FEdgePsPS, Global);

    SHADER_USE_PARAMETER_STRUCT(FEdgePsPS, FGlobalShader);

    BEGIN_SHADER_PARAMETER_STRUCT(FParameters,)
        SHADER_PARAMETER_STRUCT_REF(FViewUniformShaderParameters, View)
        SHADER_PARAMETER_RDG_TEXTURE(Texture2D, SceneColorTexture)
        SHADER_PARAMETER_SAMPLER(SamplerState, SceneColorSampler)
        RENDER_TARGET_BINDING_SLOTS()
    END_SHADER_PARAMETER_STRUCT()
};

IMPLEMENT_SHADER_TYPE(, FEdgePsPS, TEXT("/Engine/Private/DrawEdge/EdgePsShaders.usf"), TEXT("MainPS"), SF_Pixel)

void RenderEdgePs(FRDGBuilder& GraphBuilder, const FViewInfo& View, FRDGTextureRef InputColorTexture, FRDGTextureRef ViewFamilyTexture)
{
    FRDGTextureRef CopiedViewFamilyTexture = GraphBuilder.CreateTexture(ViewFamilyTexture->Desc, TEXT("CopiedViewFamilyTexture"));
    AddCopyTexturePass(GraphBuilder, ViewFamilyTexture, CopiedViewFamilyTexture);

    TShaderMapRef<FEdgePsPS> PixelShader(View.ShaderMap);
    FEdgePsPS::FParameters* PassParameters = GraphBuilder.AllocParameters<FEdgePsPS::FParameters>();
    PassParameters->View = View.ViewUniformBuffer;
    PassParameters->SceneColorSampler = TStaticSamplerState<SF_Point, AM_Clamp, AM_Clamp, AM_Clamp>::GetRHI();
    PassParameters->SceneColorTexture = CopiedViewFamilyTexture;
    PassParameters->RenderTargets[0] = FRenderTargetBinding(ViewFamilyTexture, ERenderTargetLoadAction::ENoAction);

    AddDrawScreenPass(GraphBuilder, RDG_EVENT_NAME("Edge Pass"), View,
                      FScreenPassTextureViewport(ViewFamilyTexture),
                      FScreenPassTextureViewport(ViewFamilyTexture),
                      PixelShader, PassParameters);
}

在延迟渲染管线的最后调用描边渲染Pass

在 DeferredShadingSceneRenderer.cpp 的 Render() 函数中添加代码：

if (ViewFamily.bResolveScene && ViewFamilyTexture)
{
    for (int32 i = 0; i < Views.Num(); i++)
    {
        const FViewInfo& View = Views[i];
        RenderEdgePs(GraphBuilder, View, nullptr, ViewFamilyTexture);
    }
}

引用

7 UE5.1 修改引擎源码 新增屏幕特效