崩坏学园3里离摄像机近距离的头发透明效果在unity里的实现方法

Shader "Unlit/CutPixelByDistance"
{
Properties
{
_MainTex ("Texture", 2D) = "white" {}
}
SubShader
{
Tags { "RenderType"="Opaque" "Queue" = "Transparent" }
LOD 100
Blend SrcAlpha OneMinusSrcAlpha
Pass
{
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
// make fog work
#pragma multi_compile_fog

#include "UnityCG.cginc"

struct appdata
{
float4 vertex : POSITION;
float2 uv : TEXCOORD0;
};

struct v2f
{
float2 uv : TEXCOORD0;
UNITY_FOG_COORDS(1)
float4 vertex : SV_POSITION;
float lengthInCamera : TEXCOORD1;
};

sampler2D _MainTex;
float4 _MainTex_ST;

v2f vert (appdata v)
{
v2f o;
o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);
o.uv = TRANSFORM_TEX(v.uv, _MainTex);
//计算顶点和camera之间的距离
o.lengthInCamera = length(_WorldSpaceCameraPos - v.vertex.xyz);
return o;
}

fixed4 frag (v2f i) : SV_Target
{
// sample the texture
fixed4 col = tex2D(_MainTex, i.uv);
col.a = 1;

float Start = 3;//设定开始值
float End = 2.5;//设定结束值
//如果像素和camera直接的距离小于Start则给alpha赋值
if (i.lengthInCamera < Start)
{
col.a =i.lengthInCamera /(Start - End) - End /(Start - End) ;
}
return col;
}
ENDCG
}
}
}