# 分析

由上图我们可以知道，一个消隐主要分为四个部分

• 消失边缘
• 消失内边缘
• 消失部分
• 未消失部分

其实很简单，我们只需要一张黑白噪音贴图即可，这张贴图是灰度图，我们用一个参数 **_DisAmount 来代表当前阈值，(取值 0-1), 假设噪音贴图对应 uv 坐标上的数值为 k**, 那么我们就可以判断 (k-_DisAmount) 是否小于 0 如果这个值小于 0, 就认为消失， 否则就根据值的大小来判断是外边元还是内边缘，然后直接着色即可

# 代码

//lit toon dissolve by @minionsart
Shader “Toon/Lit Dissolve” {
Properties {
_Color (“Main Color”, Color) = (0.5,0.5,0.5,1)
_MainTex (“Base (RGB)”, 2D) = “white” {}
_Ramp (“Toon Ramp (RGB)”, 2D) = “gray” {}
_NoiseTex(“Dissolve Noise”, 2D) = “white”{} // Texture the dissolve is based on
_DisAmount(“Dissolve Amount”, Range(0, 1)) = 0 // amount of dissolving going on
_DisLineWidth(“Dissolve Width”, Range(0, 2)) = 0 // width of the line around the dissolve
_DisLineColor(“Dissolve Color”, Color) = (1,1,1,1) // Color of the dissolve Line
_DisLineColorEx(“Dissolve Color Extra”, Color) = (1,1,1,1) // Color of the dissolve Line
}

SubShader{
Tags { “RenderType” = “Opaque” }
LOD 200
ZTest Less

Blend SrcAlpha OneMinusSrcAlpha // transparency
CGPROGRAM
#pragma surface surf ToonRamp keepalpha // transparency

sampler2D _Ramp;

// custom lighting function that uses a texture ramp based
// on angle between light direction and normal
#pragma lighting ToonRamp exclude_path:prepass
inline half4 LightingToonRamp (SurfaceOutput s, half3 lightDir, half atten)
{
#ifndef USING_DIRECTIONAL_LIGHT
lightDir = normalize(lightDir);
#endif

half d = dot (s.Normal, lightDir)*0.5 + 0.5;
half3 ramp = tex2D (_Ramp, float2(d,d)).rgb;

half4 c;
c.rgb = s.Albedo * _LightColor0.rgb * ramp * (atten * 2);
//c.a = 0; we don’t want the alpha
c.a = s.Alpha; // use the alpha of the surface output
return c;
}

sampler2D _MainTex;
float4 _Color;
sampler2D _NoiseTex;//
float _DisAmount;//
float _DisLineWidth;//
float4 _DisLineColor;//
float4 _DisLineColorEx;//

struct Input {
float2 uv_MainTex : TEXCOORD0;
float3 worldPos;// built in value to use the world space position

};

void surf (Input IN, inout SurfaceOutput o) {
//_DisAmount = _SinTime.w;
half4 c = tex2D(_MainTex, IN.uv_MainTex) * _Color;
half4 n = tex2D(_NoiseTex, IN.worldPos.xy); // turn the noise texture into a value we can compare to. worldPos.xy projects from one side, xz from other side, yz from top
if (n.r - (_DisLineWidth +0.1) < _DisAmount) { //if the noise value minus the width of the line is lower than the dissolve amount
c = _DisLineColorEx;
o.Emission = c.rgb;// that part is the dissolve line color
}
if (n.r - _DisLineWidth < _DisAmount) { //if the noise value minus the width of the line is lower than the dissolve amount
c = _DisLineColor ; // that part is the dissolve line color
}
if (n.r<_DisAmount) { // if the noise value is under the dissolve amount
c.a = 0.0; // it’s transparent, the alpha is set to 0
}
o.Albedo = c.rgb;
o.Alpha = c.a;
}
ENDCG

}

Fallback “Diffuse”
}