Radial Blur Shader in Unreal Engine 4

Today I've made this simple post process material, that applies a radial blur to screen. That was made for a sniper rifle mode in game, when player is looking through a optical sight. And we've got this raw effect:

 

To create this shader I use a custom node expression in material editor. You can see it's code here:

	/*
	*UV in screen space (in range from 0 to 1).
	*Radius is a size of radial blur center area. Inside of this area no blur will be applied.
	*CenterPosition is a point, to which all blur effect vectors are pointing.
	*MaxPasses is max number of blur samples.
	*Darkness is using to reduce brightness of area where blur effect was applied.
	*/
	float mask = 1.0;
	//this function is to get pixels from the Screen
	//14 is an index of PostProcessChannel. 14 means that we want to get PostProcessInput0 channel.
	float4 blur = SceneTextureLookup(UV,14,false);
	float4 viewSize = Frame.ViewSizeAndInvSize;
	float4 bufferSize = Frame.BufferSizeAndInvSize;
	//the next 5 lines are used to get proper uv coords, radius and center position
	//in relation to screen aspect and viewSize
	//without this, everything will be stretched and placed in wrong position if you are not in fullscreen
	//-------------------------------------------------------------------------
	float2 ratio = float2(bufferSize.x / viewSize.x, bufferSize.y / viewSize.y);
	float2 aspect = float2 (1.0,bufferSize.y / bufferSize.x);
	float radius = Radius * viewSize.x/bufferSize.x;
	float2 centerPosition = CenterPosition * aspect / ratio;
	float2 uv = UV * aspect;
	//-------------------------------------------------------------------------
	float2 BlurVector= centerPosition - uv;
	float dist = length(BlurVector);
	//passes are calculated progressively. the more closer we are to center, the less passes we need
	//it provieds us smooth fade between blured and clean areas.
	float passes = floor(MaxPasses * (dist/radius-1));
	if (passes < 0) passes = 0;
	if (passes > MaxPasses) passes = MaxPasses;
	if (dist < radius)
	{
	mask = 1.0 ;
	}
	else
	{
	mask = (1.0 - Darkness) * (radius/dist);
	}
	[unroll (100)]
	for (float i = 0; i< passes; i++)
	{
	blur += SceneTextureLookup ( UV + BlurVector*i*SampleSize,14,false);
	}
	//calculating average pixel color;
	return blur / (passes+1)*mask ;

view raw RadialBlur.cpp hosted with ❤ by GitHub

Just copy the source and paste it into your custom node.
Modify as you need.