Rim Shader

key point

• inversed dot product.
• using WorldSpaceViewDirection.

Code

    Shader "Custom/RimShader"
    {
    Properties 
    {
        _RimPower("Rim Power", Range(0.01, 0.1)) = 0.05
        _RimInten("Rim Intensity", Range(0.01, 100)) = 10

        [HDR]_RimColor("Rim Color", color) = (1,1,1,1)
    } 

    SubShader
    {  	
    Tags
    {
        "RenderPipeline"="UniversalPipeline"
        "RenderType"="Opaque"          
        "Queue"="Geometry"		
    }
    Pass
    {
    Name "Universal Forward"
    Tags {"LightMode" = "UniversalForward"}

    HLSLPROGRAM
    #pragma prefer_hlslcc gles
    #pragma exclude_renderers d3d11_9x
    #pragma vertex vert
    #pragma fragment frag		

    #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Lighting.hlsl"

    struct VertexInput
    {
        float4 vertex : POSITION;
        float3 normal : NORMAL;
    };

    struct VertexOutput
    {
    float4 vertex  	: SV_POSITION;
        float3 normal   : NORMAL;			
        float3 WorldSpaceViewDirection : TEXCOORD0;
    };

    float _RimPower, _RimInten;
    half4 _RimColor;	

    VertexOutput vert(VertexInput v)
    {
        VertexOutput o;      
        o.vertex = TransformObjectToHClip(v.vertex.xyz); 				         	
        o.normal = TransformObjectToWorldNormal(v.normal);
    
        // 지정된 객체 공간 정점 위치에서 카메라 방향으로 월드 공간 방향을 계산하고 정규화 함 월드공간 카메라 좌표 - 월드공간버텍스 좌표
        //o.WorldSpaceViewDirection = normalize(_WorldSpaceCameraPos.xyz - TransformObjectToWorld(v.vertex.xyz));
        o.WorldSpaceViewDirection = normalize(_WorldSpaceCameraPos.xyz - mul(GetObjectToWorldMatrix(), float4(v.vertex.xyz, 1.0)).xyz);

        return o;
    }					

    half4 frag(VertexOutput i) : SV_Target
    {	  	
        float3 light = _MainLightPosition.xyz;
        float4 color = float4(0.5, 0.5, 0.5, 1);			

        half3 ambient = SampleSH(i.normal);
    
        //월드 카메라 벡터와 노멀을 내적해 방향에 대한 값을 구합니다. 바라보는 방향이 같은 1(밝음) 90도면 0(어두움)이 됩니다.	      
        half face = saturate(dot(i.WorldSpaceViewDirection, i.normal));

        half3 rim = 1.0 - (pow(face, _RimPower));

        //emissive term	
        color.rgb *= saturate(dot(i.normal, light)) * _MainLightColor.rgb + ambient ;	

        //emissive term	
        color.rgb += rim * _RimInten * _RimColor;

        return color;
    }
    ENDHLSL  
    }
    }

}