Struggling to use OpenGL

[ChrisNielsenOrica]

I'm a huge fan of Avalonia and I'd like to use it to build a new windows desktop app that will involve a lot of 3d rendering.

I was looking at the OpenGL integration and I really like the way it's integrated into the compositor. But I was trying to do something I thought would be fairly simple, enabling multisampling anti-aliasing from this tutorial and I can't figure it out.

I've configured Win32PlatformOptions to use Win32RenderingMode.Wgl, but when I enabled gl.Enable(GL_MULTISAMPLE); nothing happened.

The tutorial calls out another option of using a multi-sample frame buffer but when I look in GlInterface.cs I can't see those methods exposed through the API. And in fact 80% of GlConsts.cs is commented out.

Am I just trying to use an experimental feature and OpenGL isn't really supported? Or are there work arounds to use OpenGL features that aren't available through the Avalonia.OpenGL project in the source code?

[maxkatz6]

Avalonia GlInterface and GlConsts only provide members that are required for Avalonia itself to work. For anything extra, you need to integrate with dedicated OpenGL libraries like Silk.NET.

See #17990 or #10646 (comment)

Can't really help with GL_MULTISAMPLE problem, as it's not my area of expertise. But generally I would recommend avoiding Win32RenderingMode.Wgl unless you need latest opengl features. Without that, Avalonia will use OpenGL-over-DirectX via Angle, which typically works more stable.

[ChrisNielsenOrica]

Hey thanks for the quick response!

Ok, that makes sense to me. So Avalonia uses the GPU for rendering normal controls and GlInterface is just the parts of OpenGL required for Avalonia to render normal 2d UI components.

The reason I was trying to use it to render a 3d scene is that I was trying to copy the implementation of the "OpenGL" disco teapot example in the "ControlCatalog.Desktop". I assumed because it's in the catalog that it's the "proper" way to use 3d in avalonia.

I'm fine to use Silk.NET, but, is there an established best practice for using 3d in Avalonia I should follow instead? I only picked OpenGL because of the teapot example.

[maxkatz6]

Long term, I would guess, Vulkan interop is better. Since it's compatible with wider set of platforms, and likely to be compatible with Apple/Metal soon too. You would still need OpenGL, if you need browser support though.

[maxkatz6]

See GPUInterop demo in this repository

[ChrisNielsenOrica]

Awesome, thanks mate,

What kind of instabilities have you observed using Win32RenderingMode.Wgl?