Problems with blur filter on DirectX12 backend

[Teknogrebo]

Hi There,

I was excited to try out the new DirectX12 rendering backend for the project I'm working on to get access to all the fancy css transition and filter functionality, and was able to swap over from the SDL backend pretty easily but when I tried to add a blur filter to my background things started going wrong. When the UI is refreshed by mousing over a button or loading a new layout, the screen flickers and I can see my layout rendered in the bottom left of the screen for a frame, or the entire screen is magnified by two for a frame, or the blur effect is removed. Basically lots of glitching.
It looks like the temporary buffers used for setting up the blur in a small region of the screen are getting mixed up somehow, but I don't know enough about DirectX to figure out what's going on.

[mikke89]

Hello!

Thanks for reporting. The DirectX 12 renderer hasn't had quite the same exposure yet, so it might not be as stable as our reference implementation in particular.

Does this happen on any usage of the blur filter, or are there some particular situations? What kind of OS and hardware do you have?

@wh1t3lord Could you take a look at this?

[wh1t3lord]

Okay I will take a look but I humbly ask that I need a test case without it I can’t reproduce. I tested on many devices, maybe there is a bug with sync problem where I just mistakenly used wrong variable and I hope it is not the case, what detailed validation says on user side?

Can user enable detailed device debugging please because if it is all clear then it is indeed some kind of sync bug. Need detail investigation.

@mikke89

[wh1t3lord]

@Teknogrebo hello there can you

change

vp.TopLeftY = source_destination.Get_Height() / 2.0f;

to vp.TopLeftY = 0;

in the RenderBlur() downsampling viewport setup.

And tell does it fix the problem?

Thanks

[Teknogrebo]

Hi. Thanks for the response.
To answer the first question, I just have this in my style sheet:
body#game_window {
decorator: image(background.png cover);
filter: blur(4px);
}
I don't know if it's actually correct as it blurs the entire screen, rather than the background, which is what I was hoping for.

To the other questions, I'm just running this on a Windows 11 Alienware laptop with an Nvidia RTX5070
I've enabled DirectX logging and included an example run. It doesn't seem to be showing much in the way of errors though.

I tried changing the code you suggested and it just resulted in a black screen that still exhibited the same glitches when mousing over an element

As for a test case, I can't provide my project as it's something I'm working on for my company, but I'll see if I can repro it in the samples. I'll be honest though and say, that since posting the bug I discovered that this implementation would need lots of work to make it compatible with XBox X/S which is one of our final targets, so this might be a dead end anyway.

log.txt

[Teknogrebo]

Okay, I've built Invaders sample with SDL_DX12 backend and changed the style to:
body
{
width: 100%;
height: 100%;
z-index: -1;
filter: blur(4px);
}
Although it works better than in my project, it still does the funny clip to the bottom left as shown in the screenshot

[wh1t3lord]

@Teknogrebo thanks feedback.

I used an agent for a quick review, but if you didn’t get any validation errors even for debug execution with validation layers it seems that it is a logical error with state of rendering and I will check manually.

About console porting I would like to hear feedback too because I thought about providing implementation for consoles but there is a problem because they like to restrict access due to singing NDA and all that so yeah we will see in the future how it will go for Mike and what he personally thinks about it.

Also I would like to hear any critique related to my implementation because I tried to assist and improve quality of life for developers who use our backends with providing buffer memory management and texture management with all possible optimizations and customization in terms how to configure these managers.

But if something not suitable for consoles then you are welcome to share your thoughts.

I would like to provide implementation for batching but right now i am doing it for vulkan :D

[Teknogrebo]

Thanks @wh1t3lord. I very much appreciate the work you've done so far. I'm more of a UI/gameplay engineer that has been tasked with a solo project which has got me digging in to the rmlui backend stuff. I believe the compatibility with XBox x/s is that it doesn't support runtime compilation of shaders so all those lovely inline shaders would need to be made external and precompiled for different platforms. In addition swapchains have been deprecated and the only interface that is available is IDXGISwapChain1 - but there are apparently better ways of doing the same thing. This is all heresay though as it's all dark magic to me!

[wh1t3lord]

@Teknogrebo hello there,

Would be great if you use my fixes from pull and confirm that blur trouble is gone

Best regards