IOException

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

Shader "Jamesloo/ScreenSpaceSnow "  
{  
    Properties  
    {  
        _MainTex ("Texture", 2D) = "white" {}  
    }  
    SubShader  
    {  
        // No culling or depth  
        Cull Off ZWrite Off ZTest Always  
  
        Pass  
        {  
            CGPROGRAM  
            #pragma vertex vert  
            #pragma fragment frag  
              
            #include "UnityCG.cginc"  
  
            struct appdata  
            {  
                float4 vertex : POSITION;  
                float2 uv : TEXCOORD0;  
            };  
  
            struct v2f  
            {  
                float2 uv : TEXCOORD0;  
                float4 vertex : SV_POSITION;  
            };  
  
            v2f vert (appdata v)  
            {  
                v2f o;  
                o.vertex = UnityObjectToClipPos(v.vertex);  
                o.uv = v.uv;  
                return o;  
            }  
              
            sampler2D _MainTex;  
            sampler2D _CameraDepthNormalsTexture;  
            float4x4 _CamToWorld;  
  
            sampler2D _SnowTex;  
            float _SnowTexScale;  
  
            half4 _SnowColor;  
  
            fixed _BottomThreshold;  
            fixed _TopThreshold;  
              
            half4 frag (v2f i) : SV_Target  
            {  
                half3 normal;  
                float depth;  
  
                DecodeDepthNormal(tex2D(_CameraDepthNormalsTexture, i.uv), depth, normal);  
                normal = mul((float3x3)_CamToWorld, normal);  
  
                // find out snow amount  
                half snowAmount = normal.g;  
                half scale = (_BottomThreshold + 1 - _TopThreshold) / 1 + 1;  
                snowAmount = saturate((snowAmount - _BottomThreshold) * scale);  
  
                 //find out snow color  
                float2 p11_22 = float2(unity_CameraProjection._11, unity_CameraProjection._22);  
                float3 vpos = float3((i.uv * 2 - 1) / p11_22, -1) * depth;  
                float4 wpos = mul(_CamToWorld, float4(vpos, 1));  
                wpos += float4(_WorldSpaceCameraPos, 0) / _ProjectionParams.z;  
  
                half4 snowColor = tex2D(_SnowTex, wpos.xz * _SnowTexScale * _ProjectionParams.z) * _SnowColor;  
  
                // get color and lerp to snow texture  
                half4 col = tex2D(_MainTex, i.uv);  
                //return col;  
                return lerp(col, snowColor, snowAmount);  
            }  
            ENDCG  
        }  
    }  
}