Interop with Direct3D 11

[Tape-Worm]

I have written a graphics API that uses Direct3D 11.x (via SharpDX), and currently it uses Windows Forms to interact with the swap chain. This API also has an editor application that is entirely built in Windows Forms. Because of this, I'm tied to .NET Framework 4.x. I am aware that .NET 5/Core 3.1 "supports" WPF/WinForms, but that support is... well... it's crap so far (at least where designers are concerned).

So, I would like to jump to .NET 5 and I've done some preliminary work on this and the performance gains were impressive even with no code changes. However the UI stuff has proven to be a painful challenge. I could jump to WPF and I have a WPF interop layer, but there are limitations that are imposed by WPF, and it introduces stuttering when rendering. It's not ideal at all. So, I'm looking into other UI frameworks and Avalonia comes up a lot as a good alternative for UI on .NET 5/Core.

So, to my question: Am I able to integrate Direct3D with Avalonia? More specifically, can I assign a swap chain to a control?

Just as a note: I have dug through the repo and I saw an interop sample there, but from the issues list, I saw that it no longer works properly (Issue #2024). But that was so long ago that things may have changed?

TLDR:
Can I interop Direct3D 11.x with Avalonia?

[kekekeks]

Can I interop Direct3D 11.x with Avalonia?

Short answer: yes, that's possible, but requires tinkering with Skia and ANGLE
Long answer:

1. configure Win32PlatformOptions to always enable GPU and AngleOptions to use DirectX11
2. implement ICustomDrawingOperation, that will give you access to Skia on the render thread, see CustomSkiaPage.cs example. Note that the following steps can be ONLY done from ICustomDrawingOperation::Draw callback.
3. import your Direct3D content from DXGI share handle, wrap it into EGLSurface, bind EGLSurface to a texture, import said texture to Skia
4. draw imported image on SKCanvas
5. cleanup

Obviously the 3rd step is the hardest one.

var egl = (EglPlatformOpenGlInterface)AvaloniaLocator.Current.GetService<IPlatformOpenGlInterface>();
var angle = (AngleWin32EglDisplay)egl.Display;

This will give you access to EGL and OpenGL entry points. AngleWin32EglDisplay already has GetDirect3DDevice and WrapDirect3D11Texture methods. EGLSurface->texture binding can be done via eglBindTexImage.

At some point I'll make it work out of the box with some simple D3DImage-like API, but that probably won't happen until summer/fall.

[kekekeks]

We do not provide full OpenGL or EGL API bindings. You'll need to use GetProcAddress from EglInterface to obtain the function pointer and use Marshal.GetDelegateFromFunctionPointer to get a delegate.

[Tape-Worm]

Fair enough. Thanks for all your help.

[Tape-Worm]

Before I forget, the WrapDirect3D11Texture method did not work for me. I've added an issue for it (#5455).

[amerkoleci]

@Tape-Worm Did you managed to handle the D3D11 part? When do you call SwapChain.Present?

[Tape-Worm]

@amerkoleci I never got this working unfortunately. And I wasn't using a swap chain for this, I was just updating a render target texture.