Shader "Unlit/Outline"
{
    Properties
    {
        _OutlineColor ("描边颜色", Color) = (0,0,0,1)
        _OutlineWidth ("描边宽度", Range(0.001, 0.1)) = 0.015
    }
    SubShader
    {
        Tags { "RenderType"="Opaque" "Queue"="Geometry+10" }
        LOD 100

        Pass
        {
            Cull Front
            ZWrite On

            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #include "UnityCG.cginc"

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

            struct v2f
            {
                float4 pos : SV_POSITION;
            };

            fixed4 _OutlineColor;
            float _OutlineWidth;

            v2f vert (appdata v)
            {
                v2f o;
                // 沿法线方向外扩顶点
                float3 expandedPos = v.vertex.xyz + v.normal * _OutlineWidth;
                o.pos = UnityObjectToClipPos(float4(expandedPos, 1.0));
                return o;
            }

            fixed4 frag (v2f i) : SV_Target
            {
                return _OutlineColor;
            }
            ENDCG
        }
    }
    FallBack "Unlit/Texture"
}