Properties {
        _MainTex("Main Texture", 2D) = "white" {}
        _CrackTex("Crack Texture", 2D) = "white" {}
        _AlphaTex("Alpha Mask Texture", 2D) = "white" {}
        [HideInInspector]_AlphaThresh("Alpha Threshold", Range(0, 1)) = 0
    }

    SubShader {
        Tags {"Queue" = "Transparent" "IgnoreProjector" = "True" "RenderType" = "Transparent"}
        LOD 100

        ZWrite Off
        Blend SrcAlpha OneMinusSrcAlpha

        Pass {
            CGPROGRAM
                #pragma vertex vert
                #pragma fragment frag
                #pragma target 2.0

                #include "UnityCG.cginc"

                struct appdata_t {
                    float4 vertex : POSITION;
                    float2 texcoord : TEXCOORD0;
                };

                struct v2f {
                    float4 vertex : SV_POSITION;
                    float2 texcoord : TEXCOORD0;
                };

                sampler2D _MainTex;
                float4 _MainTex_ST;
                sampler2D _CrackTex;
                float4 _CrackTex_ST;
                sampler2D _AlphaTex;
                float4 _AlphaTex_ST;
                float _AlphaThresh;

                v2f vert(appdata_t v) {
                    v2f o;
                    o.vertex = UnityObjectToClipPos(v.vertex);
                    o.texcoord = TRANSFORM_TEX(v.texcoord, _MainTex);
                    return o;
                }

                fixed4 frag(v2f i) : SV_Target
                {
                    fixed4 mainTex = tex2D(_MainTex, i.texcoord);
                    fixed4 crackTex = tex2D(_CrackTex, i.texcoord);
                    fixed4 alphaTex = tex2D(_AlphaTex, i.texcoord);
                    fixed4 maskedCrackTex = (alphaTex.r < 0.5) ? 0 : crackTex;
                    mainTex = saturate(mainTex + maskedCrackTex);
                    return mainTex;
                }
            ENDCG
        }
    }