Unity shader学习之Alpha Test的阴影

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

Shader "Custom/Alpha Test Shadow"
{
Properties
{
_Color ("Main Color", Color) = (1,1,1,1)          // 必需
_MainTex("Main Texture", 2D) = "white" {}
_Cutoff ("Alpha cutoff", Range(0,1)) = 0.5        // 必需
}

SubShader
{
Tags
{
"Queue" = "AlphaTest"
"RenderType" = "TransparentCutout"
}

Pass
{
Tags
{
"LightMode" = "ForwardBase"
}
Cull Off                                    // 背面

CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#pragma multi_compile_fwdbase

#include "UnityCG.cginc"
#include "Lighting.cginc"
#include "AutoLight.cginc"

float4 _Color;
sampler2D _MainTex;
float _Cutoff;

struct appdata
{
float4 vertex : POSITION;
float2 uv : TEXCOORD0;
float3 normal : NORMAL;
};

struct v2f
{
float4 pos : SV_POSITION;
float2 uv : TEXCOORD0;
float3 worldNormal : TEXCOORD1;
float3 worldPos : TEXCOORD2;
SHADOW_COORDS(3)
};

v2f vert(appdata v)
{
v2f o;
o.pos = UnityObjectToClipPos(v.vertex);
o.uv = v.uv;
o.worldNormal = UnityObjectToWorldNormal(v.normal);
o.worldPos = mul(unity_ObjectToWorld, v.vertex).xyz;
TRANSFER_SHADOW(o);
return o;
}

fixed4 frag(v2f i) : SV_TARGET
{
fixed4 albedo = tex2D(_MainTex, i.uv) * _Color;

clip(albedo.a - _Cutoff);

fixed3 ambient = albedo.rgb * UNITY_LIGHTMODEL_AMBIENT.rgb;

float3 worldLight = UnityWorldSpaceLightDir(i.worldPos);
fixed3 diff = albedo.rgb * _LightColor0.rgb * max(0, dot(i.worldNormal, worldLight));

UNITY_LIGHT_ATTENUATION(atten, i, i.worldPos);

fixed3 col = ambient + diff * atten;

return fixed4(col, 1);
}

ENDCG
}
}

Fallback "Transparent/Cutout/VertexLit"                    // 必需，阴影投射pass
}