Echo/Assets/_Project/Shaders/InteractOutline.shader

Shader "Project/InteractOutline"
{
    Properties
    {
        _OutlineColor ("Outline Color", Color) = (0,1,0,1)
        _OutlineWidth ("Outline Width", Float) = 0.02
        _Emission ("Emission", Float) = 1
        _InnerWidthScale ("Inner Width Scale", Float) = 0.6
        _OuterWidthScale ("Outer Width Scale", Float) = 1.2
        _InnerAlpha ("Inner Alpha", Range(0, 1)) = 1
        _OuterAlpha ("Outer Alpha", Range(0, 1)) = 0
    }
    SubShader
    {
        Tags { "RenderPipeline"="UniversalPipeline" "Queue"="Transparent" "RenderType"="Transparent" }
        Pass
        {
            Name "OutlineLayer3"
            Tags { "LightMode"="UniversalForward" }
            Cull Front
            ZWrite Off
            ZTest LEqual
            Blend SrcAlpha One

            HLSLPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"

            CBUFFER_START(UnityPerMaterial)
                float4 _OutlineColor;
                float _OutlineWidth;
                float _Emission;
                float _InnerWidthScale;
                float _OuterWidthScale;
                float _InnerAlpha;
                float _OuterAlpha;
            CBUFFER_END

            struct Attributes
            {
                float4 positionOS : POSITION;
                float3 normalOS : NORMAL;
            };

            struct Varyings
            {
                float4 positionHCS : SV_POSITION;
            };

            Varyings vert (Attributes input)
            {
                Varyings output;
                float t = 1.0;
                float widthScale = lerp(_InnerWidthScale, _OuterWidthScale, t);
                float3 posOS = input.positionOS.xyz + input.normalOS * (_OutlineWidth * widthScale);
                output.positionHCS = TransformObjectToHClip(posOS);
                return output;
            }

            half4 frag (Varyings input) : SV_Target
            {
                float t = 1.0;
                float alpha = lerp(_InnerAlpha, _OuterAlpha, t);
                return half4(_OutlineColor.rgb * _Emission, _OutlineColor.a * alpha);
            }
            ENDHLSL
        }

        Pass
        {
            Name "OutlineLayer0"
            Tags { "LightMode"="UniversalForward" }
            Cull Front
            ZWrite Off
            ZTest LEqual
            Blend SrcAlpha One

            HLSLPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"

            CBUFFER_START(UnityPerMaterial)
                float4 _OutlineColor;
                float _OutlineWidth;
                float _Emission;
                float _InnerWidthScale;
                float _OuterWidthScale;
                float _InnerAlpha;
                float _OuterAlpha;
            CBUFFER_END

            struct Attributes
            {
                float4 positionOS : POSITION;
                float3 normalOS : NORMAL;
            };

            struct Varyings
            {
                float4 positionHCS : SV_POSITION;
            };

            Varyings vert (Attributes input)
            {
                Varyings output;
                float t = 0.0;
                float widthScale = lerp(_InnerWidthScale, _OuterWidthScale, t);
                float3 posOS = input.positionOS.xyz + input.normalOS * (_OutlineWidth * widthScale);
                output.positionHCS = TransformObjectToHClip(posOS);
                return output;
            }

            half4 frag (Varyings input) : SV_Target
            {
                float t = 0.0;
                float alpha = lerp(_InnerAlpha, _OuterAlpha, t);
                return half4(_OutlineColor.rgb * _Emission, _OutlineColor.a * alpha);
            }
            ENDHLSL
        }

        Pass
        {
            Name "OutlineLayer1"
            Tags { "LightMode"="UniversalForward" }
            Cull Front
            ZWrite Off
            ZTest LEqual
            Blend SrcAlpha One

            HLSLPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"

            CBUFFER_START(UnityPerMaterial)
                float4 _OutlineColor;
                float _OutlineWidth;
                float _Emission;
                float _InnerWidthScale;
                float _OuterWidthScale;
                float _InnerAlpha;
                float _OuterAlpha;
            CBUFFER_END

            struct Attributes
            {
                float4 positionOS : POSITION;
                float3 normalOS : NORMAL;
            };

            struct Varyings
            {
                float4 positionHCS : SV_POSITION;
            };

            Varyings vert (Attributes input)
            {
                Varyings output;
                float t = 0.3333333;
                float widthScale = lerp(_InnerWidthScale, _OuterWidthScale, t);
                float3 posOS = input.positionOS.xyz + input.normalOS * (_OutlineWidth * widthScale);
                output.positionHCS = TransformObjectToHClip(posOS);
                return output;
            }

            half4 frag (Varyings input) : SV_Target
            {
                float t = 0.3333333;
                float alpha = lerp(_InnerAlpha, _OuterAlpha, t);
                return half4(_OutlineColor.rgb * _Emission, _OutlineColor.a * alpha);
            }
            ENDHLSL
        }

        Pass
        {
            Name "OutlineLayer2"
            Tags { "LightMode"="UniversalForward" }
            Cull Front
            ZWrite Off
            ZTest LEqual
            Blend SrcAlpha One

            HLSLPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"

            CBUFFER_START(UnityPerMaterial)
                float4 _OutlineColor;
                float _OutlineWidth;
                float _Emission;
                float _InnerWidthScale;
                float _OuterWidthScale;
                float _InnerAlpha;
                float _OuterAlpha;
            CBUFFER_END

            struct Attributes
            {
                float4 positionOS : POSITION;
                float3 normalOS : NORMAL;
            };

            struct Varyings
            {
                float4 positionHCS : SV_POSITION;
            };

            Varyings vert (Attributes input)
            {
                Varyings output;
                float t = 0.6666667;
                float widthScale = lerp(_InnerWidthScale, _OuterWidthScale, t);
                float3 posOS = input.positionOS.xyz + input.normalOS * (_OutlineWidth * widthScale);
                output.positionHCS = TransformObjectToHClip(posOS);
                return output;
            }

            half4 frag (Varyings input) : SV_Target
            {
                float t = 0.6666667;
                float alpha = lerp(_InnerAlpha, _OuterAlpha, t);
                return half4(_OutlineColor.rgb * _Emission, _OutlineColor.a * alpha);
            }
            ENDHLSL
        }
    }
}