Unity Shader script

Shader "Custom/Tree_Billboard"
{
Properties
{
   [PerRendererData] _MainTex("Sprite Texture", 2D) = "white" {}
_Color("Tint", Color) = (1,1,1,1)
   //_Time ("Time", Float) = 0
   [MaterialToggle] PixelSnap("Pixel snap", Float) = 0
}

   SubShader
{
   Tags
{
   "Queue" = "Transparent"
   "DisableBatching" = "True"
   "SortingLayer" = "Resources_Sprites"
   "IgnoreProjector" = "True"
   "RenderType" = "Transparent"
   "PreviewType" = "Plane"
   "CanUseSpriteAtlas" = "True"
}

   Cull Off
   Lighting Off
   ZWrite Off
   Blend One OneMinusSrcAlpha

   Pass
{
   CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#pragma target 2.0
#pragma multi_compile _ PIXELSNAP_ON
#pragma multi_compile _ ETC1_EXTERNAL_ALPHA
#include "UnityCG.cginc"

   //            uniform Float _Time;

struct appdata_t
{
   float4 vertex   : POSITION;
   float4 color    : COLOR;
   float2 texcoord : TEXCOORD0;
   UNITY_VERTEX_INPUT_INSTANCE_ID
};

struct v2f
{
   float4 vertex   : SV_POSITION;
   fixed4 color : COLOR;
   float2 texcoord  : TEXCOORD0;
   UNITY_VERTEX_OUTPUT_STEREO
};

fixed4 _Color;

v2f vert(appdata_t IN)
{
   v2f OUT;
   UNITY_SETUP_INSTANCE_ID(IN);
   UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(OUT);
   //                OUT.vertex = UnityObjectToClipPos(IN.vertex);
   OUT.texcoord = IN.texcoord;
   OUT.color = IN.color * _Color;
   //    #ifdef PIXELSNAP_ON

   OUT.vertex = mul(UNITY_MATRIX_P,
       mul(UNITY_MATRIX_MV, float4(0.0, 4.1, 0.0, 1.0))
       - float4(IN.vertex.x, -IN.vertex.y, 0.0, 0.0)
       * float4(6.0, 8.0, 1.0, 1.0));

   //                OUT.vertex = UnityPixelSnap (OUT.vertex);
   //    #endif

   return OUT;
}

sampler2D _MainTex;
sampler2D _AlphaTex;

fixed4 SampleSpriteTexture(float2 uv)
{
   fixed4 color = tex2D(_MainTex, uv);

#if ETC1_EXTERNAL_ALPHA
   // get the color from an external texture (usecase: Alpha support for           ETC1 on android)
   color.a = tex2D(_AlphaTex, uv).r;
#endif //ETC1_EXTERNAL_ALPHA

   return color;
}

fixed4 frag(v2f IN) : SV_Target
{
   fixed4 c = SampleSpriteTexture(IN.texcoord) * IN.color;
c.rgb *= c.a;
return c;
}
   ENDCG
}
}
}