DirectX 12 Support in Monogame: Default Behavior and Fallback

Question

Background
Monogame 4.8.0.0 documents that Windows builds use DirectX 11 by default.  The Windows Store app packaging includes a "Use DirectX 12" checkbox that generates a DX12 configuration element, but the runtime documentation does not state whether the flag automatically switches the rendering pipeline to DirectX 12 or merely signals availability to the application.
Current Uncertainty
The Monogame source contains a compile‑time directive for a 'DX12' symbol, yet there is no public API or configuration setting documented for enabling or disabling DirectX 12 at runtime.  Additionally, the fallback behavior when the target GPU does not support DirectX 12 is not explicitly described in the documentation.
Key Questions

When the "Use DirectX 12" flag is set in the Windows Store app packaging, does the Monogame runtime automatically select DirectX 12 or does it simply expose a flag for the application to query?
If the GPU lacks DirectX 12 support, does Monogame automatically fall back to DirectX 11, and how can a developer detect that fallback has occurred?
Is there a programmatic method or configuration file that can explicitly enable or disable DirectX 12 at runtime, beyond the compile‑time directive?

Tasadduq Burney · Answer

In MonoGame 4.8.0.0, DirectX 12 support is not a runtime-toggle feature but a compile-time configuration. The "Use DirectX 12" checkbox in Windows Store app packaging updates the application manifest to declare capabilities to the OS, but it does not cause the MonoGame runtime to switch its internal rendering pipeline from DX11 to DX12.

Runtime Behavior vs. Configuration
The MonoGame runtime uses different assemblies for different graphics backends. By default, Windows desktop builds target the MonoGame.Framework.Desktop.Direct11 platform. To use DirectX 12, the project must explicitly explicitly reference the MonoGame.Framework.Desktop.Direct12 assembly.

Answering the Key Questions

Does the flag automatically select DX12? No. The flag in the Store packaging merely signals to Windows that the app is DX12 compatible. The runtime continues to use DX11 unless the project is recompiled against the DX12-specific libraries.
  Is there an automatic fallback to DX11? No. If a project is compiled against the DX12 backend and runs on hardware that lacks support, the GraphicsDevice initialization will fail, typically throwing an exception. There is no built-in automatic fallback to DX11 at runtime.
  Is there a programmatic method to switch at runtime? There is no public API or configuration file to toggle between DX11 and DX12 at runtime. The backend is determined by the assemblies linked at compile time.

How to Detect the Active Backend
Since the backend is fixed at compile-time, you can verify which API is active by inspecting the GraphicsDevice properties after initialization:
// Check the graphics profile at runtime
var profile = GraphicsDevice.Device.GraphicsProfile;
Console.WriteLine("Active Graphics Profile: {profile}");

Assumptions and Uncertainty
This analysis assumes the use of the standard MonoGame Desktop template for Windows. While the source code contains DX12 symbols, these are used for conditional compilation within the platform-specific libraries rather than for a dynamic runtime-switching mechanism. It is uncertain if the DX12 implementation in 4.8.0.0 provides full feature parity with the DX11 pipeline.

DirectX 12 Support in Monogame: Default Behavior and Fallback

Background

Current Uncertainty

Key Questions

1 answer

Runtime Behavior vs. Configuration

Answering the Key Questions

How to Detect the Active Backend

Assumptions and Uncertainty

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