nighttime.shader

Shader "NightImageEffect"
{
    Properties
    {
        _MainTex ("Texture", 2D) = "white" {}
        _NightColor ("Night Color", Color) = (1,1,1,1)
        _Alpha ("Alpha", Range(0, 1)) = 1 
    }
    SubShader
    {
        // No culling or depth
        Cull Off ZWrite Off ZTest Always

        Pass
        {
            Tags 
            {
                "Queue"="Transparent" 
                "RenderType"="Transparent"
                "LightMode"="ForwardBase" 
            }

            Lighting On
            CGPROGRAM
            // Upgrade NOTE: excluded shader from DX11; has structs without semantics (struct v2f members light)
            #pragma exclude_renderers d3d11
            #pragma vertex vert
            #pragma fragment frag

            #include "UnityCG.cginc"

            uniform float4 _LightColor0;    

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

            struct v2f
            {
                float2 uv : TEXCOORD0;
                float4 vertex : SV_POSITION;
                float4 posWorld : TEXCOORD1;
                float light: COLOR0;
            };

            v2f vert (appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = v.uv;

                o.posWorld = mul(unity_ObjectToWorld, v.vertex);
                return o;
            }

            sampler2D _MainTex;
            float4 _NightColor;
            float _Alpha;

            fixed4 frag (v2f i) : SV_Target
            {
                float dist = _Alpha;
                fixed4 col = tex2D(_MainTex, i.uv);               
                float4 mult = _NightColor + (float4(1,1,1,1) * dist);
                
                return col * clamp( mult, float4(0,0,0,0), float4(1,1,1,1) );
            }
            ENDCG
        }
    }
}