using UnityEngine;
 
public class RadialBlurEffect : PostEffectBase {
 
    //模糊程度，不能过高
    [Range(0,0.05f)]
    public float blurFactor = 1.0f;
    //模糊中心（0-1）屏幕空间，默认为中心点
    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; //模糊强度（0-0.05）
uniform float4 _BlurCenter; //模糊中心点xy值（0-1）屏幕空间
#include "UnityCG.cginc"
#define SAMPLE_COUNT 6 //迭代次数
 
fixed4 frag(v2f_img i) : SV_Target
{
//模糊方向为模糊中点指向边缘（当前像素点），而越边缘该值越大，越模糊
float2 dir = i.uv - _BlurCenter.xy;
float4 outColor = 0;
//采样SAMPLE_COUNT次
for (int j = 0; j < SAMPLE_COUNT; ++j)
{
//计算采样uv值：正常uv值+从中间向边缘逐渐增加的采样距离
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 }
 
//调用CG函数
CGPROGRAM
//使效率更高的编译宏
#pragma fragmentoption ARB_precision_hint_fastest 
//vert_img是在UnityCG.cginc中定义好的，当后处理vert阶段计算常规，可以直接使用自带的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.