개요

피부용 커스텀 SSS(Subscattering Surface) 구현

SSS(Subscattering Surface)

두께맵(Thickness)을 바탕으로 마스킹한 SSS를 이미시브로 출력하고, 베이스 컬러에 약간의 혈색을 더하여 전후면 SSS를 구현하였습니다.

1. 언리얼 엔진 커스텀 노드에 입력할 HLSL 코드

// Output Type: CMOT Float 3
// Input: InLightDir, InNormalWS, InCameraVector, InThickness, InThicknessPoewr, InSSSColor, InSSSIntensity, InComplexion
// ※ InThickness: Thickness map. Thickest parts should have a value of 1. Thinnest 0.
// Additional Outputs: Complexion(CMOT Float 3)
// Output
// - result: SSS Backlight. Connect to emissive.
// - Complexion: Connect to Base Color to add complexion based on thickness map.

struct Function
{
     float3 SSS(float3 InLightDir, float3 InNormalWS, float3 InCameraVector, float InThickness, float InThicknessPower, float3 InSSSColor, float InSSSIntensity)
     {
          float3 H = InLightDir + InNormalWS;
          float3 VdotH = dot(InCameraVector, -H);
          float Thickness = pow((1 - InThickness), InThicknessPower);
          float3 result = VdotH * Thickness * InSSSColor * InSSSIntensity;

          return result;
     }

     float3 Complexion(float3 InSSSColor, float InComplexion)
     {
          float Thickness = pow((1 - InThickness), InThicknessPower);
          return Thickness * InComplexion;
     }
};

Function f;
float3 CalculatedSSS = f.SSS(InLightDir, InNormalWS, InCameraVector, InThickness, InThicknessPower, InSSSColor, InSSSIntensity);

Complexion = f.Complexion(InSSSColor, InComplexion);

return CalculatedSSS;

2. 언리얼 엔진 커스텀 노드 구성
   
   

결과 예시