Unreal
float3 o = Texture2DSample(Tex, TexSampler, UV);
for (int i = 0; i < r; i++)
{
  o+=Texture2DSample(Tex,TexSampler,UV+float2(i*dist,0));
  o+=Texture2DSample(Tex,TexSampler,UV-float2(i*dist,0));
  o+=Texture2DSample(Tex,TexSampler,UV+float2(0,i*dist));
  o+=Texture2DSample(Tex,TexSampler,UV-float2(0,i*dist));
}
o /= (4*r)+1;
return o;

--------------------------------------------------------

float Pi2 = 6.28318530718; 
float2 Radius = Size/texRes.xy;
float3 o = Texture2DSample(Tex, TexSampler, UV).xyz;
    
for( float d=0.0; d<Pi2; d+=Pi2/Directions)
{
	for(float i=1.0/Quality; i<=1.001; i+=1.0/Quality)
	{
		float2 coords = UV + float2(cos(d),sin(d))*Radius*i;
		o += Texture2DSample(Tex, TexSampler, coords).xyz;
	}
}
    
o /= Quality * Directions + 1.0;
return o;