Shader "Custom/WireframeWhiteSurface" {
    Properties {
        _WireColor ("Wire Color", Color) = (0,0,0,1) // 线框黑色
        _SurfaceColor ("Surface Color", Color) = (1,1,1,1) // 表面白色
        _Thickness ("Thickness", Range(0, 0.5)) = 0.05
    }
    SubShader {
        Tags { "RenderType"="Opaque" }
        LOD 100

        Pass {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #pragma geometry geom
            #include "UnityCG.cginc"

            struct appdata {
                float4 vertex : POSITION;
            };

            struct v2g {
                float4 vertex : POSITION;
            };

            struct g2f {
                float4 pos : SV_POSITION;
                float3 bary : TEXCOORD0;
            };

            float _Thickness;
            fixed4 _WireColor;
            fixed4 _SurfaceColor;

            v2g vert (appdata v) {
                v2g o;
                o.vertex = v.vertex;
                return o;
            }

            [maxvertexcount(3)]
            void geom(triangle v2g IN[3], inout TriangleStream<g2f> stream) {
                g2f o;
                o.bary = float3(1, 0, 0);
                o.pos = UnityObjectToClipPos(IN[0].vertex);
                stream.Append(o);

                o.bary = float3(0, 1, 0);
                o.pos = UnityObjectToClipPos(IN[1].vertex);
                stream.Append(o);

                o.bary = float3(0, 0, 1);
                o.pos = UnityObjectToClipPos(IN[2].vertex);
                stream.Append(o);
            }

            fixed4 frag (g2f i) : SV_Target {
                // 计算边缘距离
                float minBary = min(min(i.bary.x, i.bary.y), i.bary.z);
                
                // 线框部分：黑色
                if (minBary < _Thickness) {
                    return _WireColor;
                }
                // 表面部分：白色
                return _SurfaceColor;
            }
            ENDCG
        }
    }
}