Some OpenXR platforms do not support OpenGL or Vulkan. To support these
platforms we use a bridge. Blender still renders in OpenGL/Vulkan, but
will copy the render result into a D3D11 swapchain.
OpenGL doesn this by importing the D3D11 swapchain into the OpenGL
context and perfor OpenGL calls to update the swapchain. However for
vulkan that could lead to construct 3 context for OpenXR
- Blender GPU Context
- OpenXR D3D Context
- New context that imports the Blender render result and the OpenXR
Swapchain image and copies them.
Due to Direct3D limitations importing into a vulkan context has known
issues (driver + extensions). Secondly we are not sure if we are running
on the same device as the OpenXR swapchain. The solution provided with
this PR is to only support CPU data transfers.
**SteamVR using d3d bridge**
SteamVR normally would use the Vulkan binding. But by changing the binding
priority in code you can make it select the D3D bridge.
<img width="1518" alt="Screenshot 2025-04-10 114534.png" src="attachments/f856bb2b-9ad5-4bb2-9cfd-a1412da9edd1">
It has been tested and validated to work using Mixed reality portal as well.
Pull Request: https://projects.blender.org/blender/blender/pulls/137264
3da222cb9a