Shader "IndianOcean/AbyssEdgeGlow"
{
    // 悬崖边缘发光线 Shader
    // 加法混合 + Queue 3200（在黑暗遮罩之后渲染）
    // UV.y = 1 在顶部（亮），UV.y = 0 在底部（暗）
    // 用于 CliffWallBuilder 生成的边缘条带，勾勒地面断开处的轮廓
    Properties
    {
        _Color ("发光颜色", Color) = (0.2, 0.6, 0.9, 1.0)
        _Intensity ("亮度", Range(0.1, 5.0)) = 1.5
        _Gradient ("渐变（越大边缘越硬）", Range(0.1, 3.0)) = 1.0
    }
    SubShader
    {
        Tags
        {
            "RenderType" = "Transparent"
            "Queue" = "Transparent+200"
            "RenderPipeline" = "UniversalPipeline"
        }
        Blend SrcAlpha One
        ZWrite Off
        ZTest LEqual
        Cull Off

        Pass
        {
            Name "EdgeGlow"
            HLSLPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #pragma multi_compile_instancing

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

            struct Attributes
            {
                float4 positionOS : POSITION;
                float2 uv : TEXCOORD0;
                UNITY_VERTEX_INPUT_INSTANCE_ID
            };

            struct Varyings
            {
                float4 positionCS : SV_POSITION;
                float2 uv : TEXCOORD0;
                UNITY_VERTEX_INPUT_INSTANCE_ID
            };

            CBUFFER_START(UnityPerMaterial)
                float4 _Color;
                float  _Intensity;
                float  _Gradient;
            CBUFFER_END

            Varyings vert(Attributes input)
            {
                Varyings output;
                UNITY_SETUP_INSTANCE_ID(input);
                UNITY_TRANSFER_INSTANCE_ID(input, output);
                output.positionCS = TransformObjectToHClip(input.positionOS.xyz);
                output.uv = input.uv;
                return output;
            }

            half4 frag(Varyings input) : SV_Target
            {
                // UV.y: 1=顶部(亮), 0=底部(暗)
                float glow = pow(input.uv.y, _Gradient);
                float3 col = _Color.rgb * _Intensity;
                return half4(col, glow);
            }
            ENDHLSL
        }
    }
    FallBack Off
}