Shader "udSDK/Demo/SpriteBillboard" 
{
  Properties {
    _MainTex ("Texture Image", 2D) = "white" {}
    _ZOffset ("Z Offset", float) = 0.0
  }
    
  SubShader 
  {
    Tags 
    {
      "Queue" = "Transparent"
      "RenderType" = "Opaque" 
    }
    
    Pass 
    {   
      
      ZWrite On 
      AlphaToMask On
    
      CGPROGRAM

      #include "UnityCG.cginc"
      #pragma vertex vert  
      #pragma fragment frag
    
      // User-specified uniforms            
      uniform sampler2D _MainTex;        
      uniform float _ZOffset;

      struct vertexInput {
        float4 vertex : POSITION;
        float4 tex : TEXCOORD0;
      };
      struct vertexOutput {
        float4 pos : SV_POSITION;
        float4 tex : TEXCOORD0;
      };

      vertexOutput vert(vertexInput input) 
      {
        vertexOutput output;

        float3 scale = float3(
          length(unity_ObjectToWorld._m00_m10_m20),
          length(unity_ObjectToWorld._m01_m11_m21),
          length(unity_ObjectToWorld._m02_m12_m22)
        );

        output.pos = mul(UNITY_MATRIX_P,
          float4(UnityObjectToViewPos((float3)0), 1.0+_ZOffset)
          + float4(input.vertex.x, input.vertex.y, 0.0, 0.0) * 
          float4(scale.x, scale.y, 1.0, 1.0)
        );

        output.tex = input.tex;

        return output;
      }

      float4 frag(vertexOutput input) : COLOR
      {
        return tex2D(_MainTex, float2(input.tex.xy)) * input.tex.a;   
      }

      ENDCG
    }
  }
}