Half Texel Offset Blur 2.shader

Shader "BlurShader" {
	Properties{
		_MainTex("Texture", 2D) = "white" {}
		_BlurAmount("Blur Amount", Range(0, 5)) = 1
		[Toggle]_HALF_TEXEL_OFFSET("Use Half Texel Offset", Float) = 0
	}

		SubShader{
			Tags { "RenderType" = "Opaque" }
			LOD 100

			Pass {
				CGPROGRAM
				#pragma vertex vert
				#pragma fragment frag
				#pragma shader_feature _HALF_TEXEL_OFFSET_ON

				#include "UnityCG.cginc"

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

				struct v2f {
					float4 uv : TEXCOORD0;
					float4 vertex : SV_POSITION;
				};
				float4 _MainTex_ST;
				sampler2D _MainTex;
				float _BlurAmount;

				v2f vert(appdata v) {
					v2f o = (v2f)0;
					o.vertex = UnityObjectToClipPos(v.vertex);
					o.uv.xy = TRANSFORM_TEX(v.uv, _MainTex);
					#if _HALF_TEXEL_OFFSET_ON
						o.uv.zw = o.uv + 0.5 * float2(1.0 / _ScreenParams.x, 1.0 / _ScreenParams.y);
					#endif
					return o;
				}

				fixed4 frag(v2f i) : SV_Target {
					fixed4 col = fixed4(0, 0, 0, 0);
					float blurSize = _BlurAmount / _ScreenParams.y;
#if _HALF_TEXEL_OFFSET_ON
					float weight = 0.04;
#else
					float weight = 0.1111111;
#endif
					float2 offsets[4] = { float2(0, 1), float2(1, 0), float2(1, 1), float2(1, -1) }

					float2 inverseOffset = float2(i.uv.z, i.uv.w - 1 * (1 / _ScreenParams.x));
					for (int j = 0; j < 4; j++) {
						float2 offset = offsets[j] * blurSize;
#if _HALF_TEXEL_OFFSET_ON
						col += tex2D(_MainTex, i.uv.zw + offset) * weight;
						col += tex2D(_MainTex, i.uv.zw - offset) * weight;
						col += tex2D(_MainTex, inverseOffset + offset) * weight;
						col += tex2D(_MainTex, inverseOffset - offset) * weight;
#endif
						col += tex2D(_MainTex, i.uv.xy + offset) * weight;
						col += tex2D(_MainTex, i.uv.xy - offset) * weight;
					}
					col += tex2D(_MainTex, i.uv.xy) * weight;

					return col;
				}
				ENDCG
			}
		}
			FallBack "Diffuse"
}