Shader "SupGames/FastMotionBlur_Subtle"
{
    Properties
    {
        _MainTex ("Texture", 2D) = "white" {}
        _BlurStrength ("Blur Strength", Range(0, 1)) = 0.3
    }
    SubShader
    {
        Cull Off ZWrite Off ZTest Always
        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            #include "UnityCG.cginc"

            sampler2D _MainTex;
            float _Distance;
            float _BlurStrength;
            float4x4 _CurrentToPreviousViewProjectionMatrix;

            struct v2f
            {
                half4 uv : TEXCOORD0;
                half4 vertex : SV_POSITION;
                half4 uv1 : TEXCOORD1;
                half4 uv2 : TEXCOORD2;
            };

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

                half4 projPos = half4(v.texcoord.xy * 2.0h - 1.0h, _Distance, 1.0h);
                half4 previous = mul(_CurrentToPreviousViewProjectionMatrix, projPos);
                previous /= previous.w;

                // Reduced velocity scale here!
                half2 vel = (previous.xy - projPos.xy) * _BlurStrength;

                o.uv.xy = v.texcoord.xy;
                o.uv.zw = v.texcoord.xy + vel * 1.0h;
                o.uv1.xy = v.texcoord.xy + vel * 2.0h;
                o.uv1.zw = v.texcoord.xy + vel * 3.0h;
                o.uv2.xy = v.texcoord.xy + vel * 4.0h;
                o.uv2.zw = v.texcoord.xy + vel * 5.0h;
                return o;
            }

            fixed4 frag(v2f i) : SV_Target
            {
                fixed4 col = tex2D(_MainTex, i.uv.xy);
                col += tex2D(_MainTex, i.uv.zw);
                col += tex2D(_MainTex, i.uv1.xy);
                col += tex2D(_MainTex, i.uv1.zw);
                col += tex2D(_MainTex, i.uv2.xy);
                col += tex2D(_MainTex, i.uv2.zw);
                return col * 0.166667h; // Average of 6 samples
            }
            ENDCG
        }

        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            #include "UnityCG.cginc"

            sampler2D _MainTex;
            sampler2D _BlurTex;
            sampler2D _MaskTex;

            struct v2f
            {
                half2 uv : TEXCOORD0;
                half4 vertex : SV_POSITION;
            };

            v2f vert(appdata_img v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = v.texcoord.xy;
                return o;
            }

            fixed4 frag(v2f i) : SV_Target
            {
                fixed4 col = tex2D(_MainTex, i.uv);
                fixed4 blur = tex2D(_BlurTex, i.uv);
                fixed mask = tex2D(_MaskTex, i.uv).r;
                return lerp(col, blur, mask);
            }
            ENDCG
        }
    }
}