Shader "Custom/AirWall"
{
    Properties
    {
        _MainTex ("Texture", 2D) = "white" {}
        _Threshold1 ("Threshold 1", Range(0, 10)) = 0.5
        _Threshold2 ("Threshold 2", Range(0, 10)) = 2
        _WorldPos ("WorldPos", Vector) = (0, 0, 0, 0)
        _Color ("Color", Color) = (1,1,1,1)
        _FlowSpeed ("Flow Speed", Range(0, 1)) = 0.1
        _NoiseTex ("Noise Texture", 2D) = "white" {}
        _Speed ("Speed", Range(0, 10)) = 1
        _Strength ("Strength", Range(0, 1)) = 0.1
    }
    SubShader
    {
        Tags
        {
            "Queue"="Transparent" "RenderType"="Transparent"
        }
        Blend SrcAlpha OneMinusSrcAlpha
        Cull Off
        Zwrite off
        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #include "UnityCG.cginc"

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

            struct v2f
            {
                float4 pos : SV_POSITION;
                float3 worldPos : TEXCOORD0;
                float2 uv : TEXCOORD1;
            };

            sampler2D _MainTex;
            float4 _MainTex_ST;
            float _Threshold1;
            float _Threshold2;
            float4 _WorldPos;
            fixed4 _Color;
            uniform float _FlowSpeed;
            float4 _LevelRect;
            sampler2D _NoiseTex;
            float _Speed;
            float _Strength;

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

            fixed4 frag(v2f i) : SV_Target
            {
                //裁剪
                float distance = length(i.worldPos - _WorldPos.xyz);
                float rate = saturate((distance - _Threshold1) / (_Threshold2 - _Threshold1));
                float alpha = 1.0 - pow(rate, 0.5f);

                float2 offset = float2(0, _Time[0] * _FlowSpeed);
                float2 offsetNoise = float2(_Time[0] * _Speed, _Time[0] * _Speed);
                float4 noise = tex2D(_NoiseTex, i.uv + offsetNoise);
                float2 uv = i.uv + offset + noise.rg * _Strength;
                alpha = alpha * tex2D(_MainTex, uv * _MainTex_ST.xy).r;
                fixed4 col = fixed4(_Color.rgb, alpha);
                return col;
            }
            ENDCG
        }
    }
    FallBack "Diffuse"
}