shader代码
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Alpha-Parallax.shader

// Unity built-in shader source. Copyright (c) 2016 Unity Technologies. MIT license (see license.txt)

Shader "Legacy Shaders/Transparent/Parallax Diffuse" {
Properties {
    _Color ("Main Color", Color) = (1,1,1,1)
    _Parallax ("Height", Range (0.005, 0.08)) = 0.02
    _MainTex ("Base (RGB) Trans (A)", 2D) = "white" {}
    _BumpMap ("Normalmap", 2D) = "bump" {}
    _ParallaxMap ("Heightmap (A)", 2D) = "black" {}
}

SubShader {
    Tags {"Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="Transparent"}
    LOD 500

CGPROGRAM
#pragma surface surf Lambert alpha:fade

sampler2D _MainTex;
sampler2D _BumpMap;
sampler2D _ParallaxMap;
fixed4 _Color;
float _Parallax;

struct Input {
    float2 uv_MainTex;
    float2 uv_BumpMap;
    float3 viewDir;
};

void surf (Input IN, inout SurfaceOutput o) {
    //计算视差偏移
    half h = tex2D (_ParallaxMap, IN.uv_BumpMap).w;
    float2 offset = ParallaxOffset (h, _Parallax, IN.viewDir);
    IN.uv_MainTex += offset;
    IN.uv_BumpMap += offset;

    fixed4 c = tex2D(_MainTex, IN.uv_MainTex) * _Color;
    o.Albedo = c.rgb;
    o.Alpha = c.a;
    o.Normal = UnpackNormal(tex2D(_BumpMap, IN.uv_BumpMap));
}
ENDCG
}

FallBack "Legacy Shaders/Transparent/Bumped Diffuse"
}

UnityCG.cginc

// Calculates UV offset for parallax bump mapping
inline float2 ParallaxOffset( half h, half height, half3 viewDir )
{
    h = h * height - height/2.0;
    float3 v = normalize(viewDir);
    v.z += 0.42;
    return h * (v.xy / v.z);
}

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