// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

Shader "Unlit/DissolveEffect" 
{  
    Properties{  
        _Diffuse("Diffuse", Color) = (1,1,1,1)  
        _DissolveColor("Dissolve Color", Color) = (0,0,0,0)  
        _DissolveEdgeColor("Dissolve Edge Color", Color) = (1,1,1,1)  
        _MainTex("Texture", 2D) = "white" {}    
        _DissolveMap("DissolveMap", 2D) = "white"{}  
        _DissolveThreshold("DissolveThreshold", Range(0,1)) = 0  
        _ColorFactor("ColorFactor", Range(0,1)) = 0.7  
        _DissolveEdge("DissolveEdge", Range(0,1)) = 0.8  
    }  
      
    CGINCLUDE  
    #include "Lighting.cginc"  
    uniform fixed4 _Diffuse;  
    uniform fixed4 _DissolveColor;  
    uniform fixed4 _DissolveEdgeColor;  
    uniform sampler2D _MainTex;  
    uniform float4 _MainTex_ST;  
    uniform sampler2D _DissolveMap;  
    uniform fixed _DissolveThreshold;  
    uniform fixed _ColorFactor;  
    uniform fixed _DissolveEdge;  
      
    struct v2f  
    {  
        half4 pos : SV_POSITION;  
       // half3 worldNormal : TEXCOORD0;  
        half2 uv : TEXCOORD1;  
    };  
      
    v2f vert(appdata_base v)  
    {  
        v2f o;  
        o.pos = UnityObjectToClipPos(v.vertex);  
        o.uv = TRANSFORM_TEX(v.texcoord, _MainTex);  
        //o.worldNormal = mul(v.normal, (float3x3)unity_WorldToObject);  
        return o;  
    }  
      
    fixed4 frag(v2f i) : SV_Target  
    {  
        //采样Dissolve Map  
        fixed4 dissolveValue = tex2D(_DissolveMap, i.uv);  
        //小于阈值的部分直接discard  
        if (dissolveValue.r < _DissolveThreshold)  
        {  
            discard;  
        }  
        //Diffuse + Ambient光照计算  
        //fixed3 worldNormal = normalize(i.worldNormal);  
        //fixed3 worldLightDir = normalize(_WorldSpaceLightPos0.xyz);  
        //fixed3 lambert = saturate(dot(worldNormal, worldLightDir));  
       // fixed3 albedo = lambert * _Diffuse.xyz * _LightColor0.xyz + UNITY_LIGHTMODEL_AMBIENT.xyz;  
        fixed3 color = tex2D(_MainTex, i.uv).rgb; //* albedo;  
  
        //优化版本，尽量不在shader中用分支判断的版本,但是代码很难理解啊....  
        fixed percentage = _DissolveThreshold / dissolveValue.r;  
        //如果当前百分比 - 颜色权重 - 边缘颜色  
        fixed lerpEdge = sign(percentage - _ColorFactor - _DissolveEdge);  
        //貌似sign返回的值还得saturate一下，否则是一个很奇怪的值  
        fixed3 edgeColor = lerp(_DissolveEdgeColor.rgb, _DissolveColor.rgb, saturate(lerpEdge));  
        //最终输出颜色的lerp值  
        fixed lerpOut = sign(percentage - _ColorFactor);  
        //最终颜色在原颜色和上一步计算的颜色之间差值（其实经过saturate（sign（..））的lerpOut应该只能是0或1）  
        fixed3 colorOut = lerp(color, edgeColor, saturate(lerpOut));  
        return fixed4(colorOut, 1);  
    }  
    ENDCG  
      
    SubShader  
    {  
        Tags{ "RenderType" = "Opaque" }  
        Pass  
        {  
            CGPROGRAM  
            #pragma vertex vert  
            #pragma fragment frag     
            ENDCG  
        }  
    }  
    //FallBack "Diffuse"  
}