Billboarding Shader

Shader "Sprites/Billboard" {
   Properties {
      _MainTex ("Texture Image", 2D) = "white" {}
    _Color ("Main Color", Color) = (1,1,1,1)
      _ScaleX ("Scale X", Float) = 1.0
      _ScaleY ("Scale Y", Float) = 1.0
   }
   SubShader {
      Pass {
         Tags{"QUEUE" = "AlphaTest" "RenderType" = "TransparentCutout" }
         AlphaToMask On
        ColorMask RGB
         Cull Off

         CGPROGRAM

         #pragma vertex vert
         #pragma fragment frag

         // User-specified uniforms
         uniform sampler2D _MainTex;
         fixed4 _Color;
         uniform float _ScaleX;
         uniform float _ScaleY;

         struct vertexInput {
            float4 vertex : POSITION;
            float2 uv : TEXCOORD0;
            fixed4 color : COLOR;
         };
         struct vertexOutput {
            float2 uv : TEXCOORD0;
            float4 pos : SV_POSITION;
            fixed4 color : COLOR;
         };

         vertexOutput vert(vertexInput input)
         {
            vertexOutput o;

            o.pos = UnityObjectToClipPos(input.vertex);
            o.uv = input.uv.xy;

            // billboard mesh towards camera
            float3 vpos = mul((float3x3)unity_ObjectToWorld, input.vertex.xyz);
            float4 worldCoord = float4(unity_ObjectToWorld._m03, unity_ObjectToWorld._m13, unity_ObjectToWorld._m23, 1);
            float4 viewPos = mul(UNITY_MATRIX_V, worldCoord) + float4(vpos, 0);
            float4 outPos = mul(UNITY_MATRIX_P, viewPos);

            o.pos = outPos;
            o.color = input.color;

            return o;
         }

         float4 frag(vertexOutput input) : COLOR
         {
            // sample the texture
            fixed4 col = tex2D(_MainTex, input.uv);
            return col;
         }

         ENDCG
      }
   }
}