(Ubuntu 17.10) Veldrid.VeldridException: The required instance extension was not available: Veldrid.Vk.FixedUtf8String about veldrid HOT 5 CLOSED

Sure thing! From what you've described, it's probably just defaulting to the OpenGL backend now, rather than trying to use Vulkan when it's not supported. You could possibly still get Vulkan to work, but it might involve fiddling with the packages on your system. Anyways, let me know if you have any more questions or concerns. Cheers!

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Switching

_graphicsDevice = VeldridStartup.CreateGraphicsDevice(window);
to
_graphicsDevice = VeldridStartup.CreateDefaultOpenGLGraphicsDevice(new GraphicsDeviceOptions(), window);

Makes it work, which seems to imply its a problem with Vulkan dependencies on my system?

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Right now, the Vulkan backend requires the Vulkan Xlib extension (VK_KHR_xlib_surface) to be available. The error message is wrong -- it should print out that extension's name, not "Veldrid.Vk.FixedUtf8String" 😅. I've fixed that with the latest commit (da6721d)

Makes it work, which seems to imply its a problem with Vulkan dependencies on my system?

Yes, that seems to be the most likely problem. On my Ubuntu machine, I have the following packages installed for Vulkan:

• libvulkan-dev
• libvulkan1
• vulkan-utils

I don't think all of those are necessary, but adding those could be a good start.

If you have the "vulkaninfo" program installed (it's in the vulkan-utils package), then seeing the output from it would be helpful. It prints out all of the available extensions and some other diagnostic info.

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I made several changes to help detect when the system doesn't support Vulkan, and to avoid using it in those cases:

• There is a new method GraphicsDevice.IsBackendSupported, which lets you ask up front whether a backend is supported.
• The Vulkan backend checks two things to determine if it's supported:
  • Whether Vulkan functions were even successfully loaded
  • Whether the necessary extensions are available (VK_KHR_surface and the platform-specific surface extension).
• VeldridStartup now checks if Vulkan is supported before using it as the default backend on Linux. For you, it should automatically select OpenGL, unless you are able to get Vulkan drivers working for your system. Then it should just work with Vulkan.
• Mentioned above -- the Vulkan error message is correct now and actually prints out the missing extension's name.

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I just pulled latest from master and ran the same code I attached above, and the blank window appeared and stayed - no crash. (I didn't install the missing Vulkan dependencies either)

Thank you for the quick turn around on that fix!

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