Blurring below UMG elements - is it possible?

[ronaldburns]

@Nick Darnell;397544

The way Unreal is setup, each material has a domain. Each domain has a specific responsibility with a lot of plumbing in the renderer, so for example, the post process material domain, is able to access final scene color and such so that it can do post processing on it. Unfortunately Slate isn’t yet well integrated with this pipeline. We’ve setup the UI material domain for UMG, but it will need a lot more work to gain access to the right rendering bits in the pipeline. Additionally, it has added complexity if you want to blur multiple layers, essentially every time you want to blur a new layer, a new resolve step and intermediary Render Target is necessary. Lots of complexity, lots of thought will be needed to evolve UMG/Slate to handle that case well. Probably when we attempt to tackle general post processing for widgets.

For the time being, if you only need to blur directly behind the widgets, and do not need to also blur the widgets, there is a solution, but it’s tricky. The trick is to make a standard post process material, that blurs some set of quads you specify dynamically. You’d make a set of special ‘blurry widgets’ that communicate with this single post process material and keep it updated with the rects needed to be blurred.

Can we please get an example of this? It’s nearly a year later and we’re still trying to figure out how to do this.