Shader "SaberShad/RadiusBlur"
{
    Properties
    {
        [HideInInspector]_MainTex ("Texture", 2D) = "white" {}
        // 径向模糊数据 xy分量代表径向中心点  z分量代表偏移 
        _RadiusData("Radius Data", Vector) = (0.5, 0.5, 0.0, 1.0)
        // y分量代表迭代次数的倒数 例如迭代30次就是1/30
        _RadiusIterationData("Radius Iteration", Vector) = (1.0, 1.0, 0.0, 0.0)
    }
    SubShader
    {
        CGINCLUDE
            #include "UnityCG.cginc"

            sampler2D _MainTex;
            float4 _MainTex_ST;
            float4 _MainTex_TexelSize;
            half3 _RadiusData;
            half2 _RadiusIterationData;

            struct a2f_rb
            {
                float4 vertex : POSITION;
                float2 uv : TEXCOORD0;
            };

            struct v2f_rb
            {
                float4 vertex : SV_POSITION;
                float2 texcoord: TEXCOORD0;
            };

            v2f_rb RadiusBlurVertex(a2f_rb v)
            {
                v2f_rb o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.texcoord = v.uv;
                // #if UNITY_UV_STARTS_AT_TOP
                    // o.texcoord = o.texcoord * float2(1.0, -1.0) + float2(0.0, 1.0);
                // #endif
                o.texcoord = TRANSFORM_TEX(o.texcoord, _MainTex);

                return o;
            }

            half4 RadiusBlurFragment(v2f_rb i): SV_Target
            {
                half2 radiusRange = (_RadiusData.xy - i.texcoord.xy) * _RadiusData.z;

                half4 color = 0.0;
                [unroll(30)]
                for(int j = 0; j < _RadiusIterationData.x; j++)
                {
                    color += tex2D(_MainTex, i.texcoord);
                    i.texcoord += radiusRange;
                }

                return color * _RadiusIterationData.y;
            }
        ENDCG

        Cull Off ZWrite Off ZTest Always
		
		Pass
		{
			CGPROGRAM
			
			#pragma vertex RadiusBlurVertex
			#pragma fragment RadiusBlurFragment
			
			ENDCG
			
		}
    }
}