UMG BackgroundBlur "Apply Alpha to Blur" functionality?

Development Programming & Scripting UI
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1

Hello, on the UMG Background Blur widget, there is a property called “Apply Alpha to Blur”, however the description of it is quite vague: When true, this will modulate the strength of the blur based on the widget alpha.

You can’t directly set the widget alpha, only it’s fallback image alpha. Putting an alpha image as a child does nothing either.

How does this property work? Can it be used with a transparent image to create a masked blur?

Thanks!

2

I would also be interested in this question

3

I was wondering the same, so I looked at the source code (UE4 4.20) to understand the behavior :

			// Modulate blur strength by the widget alpha
			const float Strength = BlurStrength.Get() * (bApplyAlphaToBlur ? InWidgetStyle.GetColorAndOpacityTint().A : 1.f);

(From : UnrealEngine\Engine\Source\Runtime\Slate\Private\Widgets\Layout\SBackgroundBlur.cpp )

The BlurStrength parameter is multiplied by the Tint Color alpha value. The Image is only used for the fallback, so the parameter won’t be affected by it.

4

I am interested in this as well!!! the answer is not clear!

5

Where should we use the alpha texture or the “Tint Color” alpha value?