using UnityEngine;
 
public class RadialBlurEffect : PostEffectBase {
 
    //模糊程度，不能過高
    [Range(0,0.05f)]
    public float blurFactor = 1.0f;
    //模糊中心（0-1）屏幕空間，默認(rèn)為中心點
    public Vector2 blurCenter = new Vector2(0.5f, 0.5f);
 
void OnRenderImage (RenderTexture source, RenderTexture destination)
    {
        if (_Material)
        {
            _Material.SetFloat("_BlurFactor", blurFactor);
            _Material.SetVector("_BlurCenter", blurCenter);
            Graphics.Blit(source, destination, _Material);
        }
        else
        {
            Graphics.Blit(source, destination);
        }   
} 
}

Shader "ApcShader/PostEffect/RadialBlurShader1" 
{
Properties 
{
_MainTex ("Base (RGB)", 2D) = "white" {}
}
 
CGINCLUDE
uniform sampler2D _MainTex;
uniform float _BlurFactor; //模糊強度（0-0.05）
uniform float4 _BlurCenter; //模糊中心點xy值（0-1）屏幕空間
#include "UnityCG.cginc"
#define SAMPLE_COUNT 6 //迭代次數(shù)
 
fixed4 frag(v2f_img i) : SV_Target
{
//模糊方向為模糊中點指向邊緣（當(dāng)前像素點），而越邊緣該值越大，越模糊
float2 dir = i.uv - _BlurCenter.xy;
float4 outColor = 0;
//采樣SAMPLE_COUNT次
for (int j = 0; j < SAMPLE_COUNT; ++j)
{
//計算采樣uv值：正常uv值+從中間向邊緣逐漸增加的采樣距離
float2 uv = i.uv + _BlurFactor * dir * j;
outColor += tex2D(_MainTex, uv);
}
//取平均值
outColor /= SAMPLE_COUNT;
return outColor;
}
ENDCG
 
SubShader
{
Pass
{
ZTest Always
Cull Off
ZWrite Off
Fog{ Mode off }
 
//調(diào)用CG函數(shù)
CGPROGRAM
//使效率更高的編譯宏
#pragma fragmentoption ARB_precision_hint_fastest 
//vert_img是在UnityCG.cginc中定義好的，當(dāng)后處理vert階段計算常規(guī)，可以直接使用自帶的vert_img
#pragma vertex vert_img
#pragma fragment frag 
ENDCG
}
}
Fallback off
}

Direct3D-like: The coordinate is 0 at the top and increases downward. This applies to Direct3D, Metal and consoles.

OpenGL-like: The coordinate is 0 at the bottom and increases upward. This applies to OpenGL and OpenGL ES.

This difference tends not to have any effect on your project, other than when rendering into a Render Texture. When rendering into a Texture on a Direct3D-like platform, Unity internally flips rendering upside down. This makes the conventions match between platforms, with the OpenGL-like platform convention the standard.Image Effects and rendering in UV space are two common cases in the Shaders where you need to take action to ensure that the different coordinate conventions do not create problems in your project.

When you use Image Effects and anti-aliasing, the resulting source Texture for an Image Effect is not flipped to match the OpenGL-like platform convention. In this case, Unity renders to the screen to get anti-aliasing and then resolves rendering into a Render Texture for further processing with an Image Effect.

If your Image Effect is a simple one that processes one Render Texture at a time, Graphics.Blit deals with the inconsistent coordinates. However, if you’re processing more than one Render Texture together in your Image Effect, the Render Textures are likely to come out at different vertical orientations in Direct3D-like platforms and when you use anti-aliasing. To standardise the coordinates, you need to manually “flip” the screen Texture upside down in your Vertex Shader so that it matches the OpenGL-like coordinate standard.