Different MSAA count # for antialiasing? (SampleDescription in SwapChainDescription)

[bkoo-intel]

I tried to run an example I got from "https://juhakeranen.com/winui3/"
It was successful to run it without MSAA (using SampleDescription(1,0)).
However, when I enabled antialiasing by changing the 'SampleDescription' to use MSAA like this.

++++++
SwapChainDescription1 swapChainDesc = new SwapChainDescription1()
{
Stereo = false,
Width = (int)SwapChainCanvas.Width,
Height = (int)SwapChainCanvas.Height,
BufferCount = 2,
BufferUsage = Usage.RenderTargetOutput,
Format = Format.B8G8R8A8_UNorm,
SampleDescription = new SampleDescription(2, 1),
Scaling = Scaling.Stretch,
AlphaMode = Vortice.DXGI.AlphaMode.Premultiplied,
Flags = SwapChainFlags.None,
SwapEffect = SwapEffect.FlipSequential
};
++++++

The program crashed.
I got the following error message.

++++++
Unhandled exception at 0x00007FF99625D8BC (Microsoft.ui.xaml.dll) in D3DWinUI3.exe: 0xC000027B: An application-internal exception has occurred (parameters: 0x00000291DC78BFE0, 0x0000000000000002).
++++++

Could you please let me know if there’s anything I need to define or configure in order to use MSAA properly with WinUI 3 and Direct3D? Any guidance would be greatly appreciated.

[amerkoleci]

Hi,
Setup an example and I'll give a look

Thanks!

[Gavin-Williams]

@bkoo-intel With WinUI and UWP, those swap-chain models don't support msaa - but you still have to use them. So the solution is to render to a texture and then either resolve it to the swap-chain if it's the same dimensions or else draw a textured quad to the swap-chain with your render-target as the shader-resource.

It's a bit of extra work, but in addition to having to do it to enable msaa, it solves a couple of problems later on, so you probably want to do it that way anyhow.

[bkoo-intel]

Thank you for the advice, Gavin!
Let me try to digest your comments and change the codes accordingly. 👍

[Gavin-Williams]

Resolving a texture to the swapchain can be as simple as this...

public void ResolveToMS1Texture()
{
    ID3D11DeviceContext dc = Gpu.DeviceContext;

    if (MSCount != MultiSampleCount.Level1)
    {
        Format dstFormat = hdrTextureT2d_MS1!.Description.Format;
        dc.ResolveSubresource(hdrTextureT2d_MS1, 0, hdrTextureT2d_MSx, 0, dstFormat);
    }
}

[bkoo-intel]

Hi Gavin,

Thanks for sharing the function. Since I'm new to WinUI3 and C#, could you please modify the example I attached (link above) to include your function? I'm not sure how to integrate it with the existing code.

For your convenience, here is the link of the files as well. 👍
d3dwinui3pt8.zip

Thanks!

[Gavin-Williams]

I can fix it up for you. I didn't include the code to create the offscreen texture there - that was just showing the resolve function. So it wouldn't work as is.

[Gavin-Williams]

Here you go...
d3dwinui3pt8.zip

Just make sure you keep the offscreen texture the same size as the swapchain.

And by the way, I don't think you can change the quality level like you did above. I've always left quality at zero. I remember AMD never used to support different quality levels. So, I never touched it. I tried changing those values just now and it still didn't work, and I have an NVidia card these days. So without doing some research I suspect you can't configure the quality level. And keep in mind, quality isn't necessarily quality. Think of it like a sampling mode.

[bkoo-intel]

Thank you very much for taking the time to change the code for me!
I really appreciate it. 🙏