Support/Unity-Editor-Freeze.md

+Figments.nrw supports OpenXR and thus headsets of different vendors. Especially on development machines it can occur that multiple headsets are being used.
+In most cases, this will not break anything. But in some cases it will, more often than not in relation to SteamVR, driver issues or parallel configuration files.
+
+This article describes issues that *may* arise when you use multiple different headsets on your device.
+
+## Unity experiences a Hard Freeze on Play Mode
+When running Figments.nrw in the Unity Editor, the Editor may hard freeze when you try to enter the Play Mode. This error more often than not manifests something like this:
+
+1. Open Figments.nrw in Unity
+2. Hit Play
+3. Unity experiences a Hard Freeze
+	1. The Editor will become completely unresponsive
+	2. You will need to end the Editor task in the taskmanager
+
+While developing Figments.nrw we identified two sources for these issues that may or may not be in relation to each other.
+
+### Clashing Streaming Applications
+Figments.nrw is tested with the Pico 3 Eye Pro, Pico 4 and Pico 4 Enterprise Edition and it runs on all of these devices in standalone mode as well as when streaming via OpenXR/SteamVR in a PC-VR configuration.
+
+Pico provides a specific streaming application for each of their devices, some of which are deprecated or do not play nicely with each other.
+
+In our tests, we used the following apps:
+- Pico 3 Eye Pro: Pico Link
+- Pico 4: Pico Connect
+- Pico 4 Enterprise: Pico Business Streaming
+
+Installing and running more than one of these apps will likely lead to the aforementioned hard freeze.
+
+This error is related to the way OpenXR handles external drivers that are used to stream content to a headset.
+
+When installing and using multiple streaming apps (e.g. from Pico, Microsoft and/or Meta) a configuration file (see below) can include multiple entries for external drivers, which apparently is not supported in SteamVR.
+
+The culprit can be found in
+`%LocalAppData%\openvr`.
+
+If you open `openvrpaths.vrpath`, it may look something like this:
+
+```
+{
+	"config" : 
+	[
+		"C:\\Program Files (x86)\\Steam\\config",
+		"C:\\Program Files (x86)\\Steam\\config/"
+	],
+	"external_drivers" : 
+	[
+		"C:\\Program Files\BusinessStreaming\\BusinessStreamingUW\\driver",
+		"C:\\Program Files (x86)\\Pico Link\\driver",
+		"C:\\Program Files (x86)\\Steam\\steamapps\\common\\MixedRealityVRDriver"
+	],
+	"jsonid" : "vrpathreg",
+	"log" : 
+	[
+		"C:\\Program Files (x86)\\Steam\\logs",
+		"C:\\Program Files (x86)\\Steam\\logs/"
+	],
+	"runtime" : 
+	[
+		"C:\\Program Files (x86)\\Steam\\steamapps\\common\\SteamVR"
+	],
+	"version" : 1
+}
+```
+
+If the key `external_drivers` contains more than one entry (in this example one for PICO Business Streaming, one for Pico Link), delete the one you currently do not use.
+
+This should fix this particular error of Unity's hard freeze.
+
+### SteamVR
+In some cases SteamVR may simply be broken or corrupted. We could not reliably reproduce this error, but it occured on the same devices that ran multiple different headsets.
+
+The issues manifested not only with the aforementioned hard freeze of the editor, but with SteamVR not loading the SteamVR Home environment when running the streaming application as well.
+
+If you experience a hard freeze of the Unity Editor, but the previously shown method of fixing the external driver references did not fix the issue, you can try to delete and reinstall SteamVR.
+
+On our devices this fixed the issue.
\ No newline at end of file