OpenXR-SDK-Source
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KhronosGroup
Layer usage is poorly documented
The main documentation for layers seems to be api_layer.adoc, but this contains a great deal of information (e.g. manifest spec, negotiation) that's not pertinent to the common case of a developer who just wants to install/enable the validation/dump layers. Worse, it doesn't mention XR_ENABLE_API_LAYERS at all; in fact this critical variable only has 9 google results, none of which are official documentation. Finally, it's not actually linked from the README of this or the OpenXR-SDK repository, or from any Khronos pages I could find; I wouldn't have discovered it at all were I not lurking in the Monado discord while it was mentioned by @ChristophHaag. Layer-specific docs are similarly obscure.
It's also confusing that (unlike Vulkan) the layers are not included in the standard SDK build. It's nice that Windows binaries are available in this repo's releases, but it would be nicer if they came standard. End users aren't installing the SDK. That said, it's also convenient to have a lightweight loader-only source archive available for use in build system magic, so maybe the problem here is just one of discoverability.
The variable is mentioned in this readme but I agree, it should probably go into the loader doc too https://github.com/KhronosGroup/OpenXR-SDK-Source/blob/master/src/api_layers/README.md
That README has exactly the information I'd have liked to find, yeah--it, too, just doesn't seem to be linked from anywhere.
An issue (number 1594) has been filed to correspond to this issue in the internal Khronos GitLab (Khronos members only: KHR:openxr/openxr#1594 ), to facilitate working group processes.
This GitHub issue will continue to be the main site of discussion.
Totally agree this is a discoverability issue.
I have just gone through all the steps Ralith has. I was confused that requests for API layer count was always zero, being used to Vulkan installing the layers as part of the SDK. I can see now how you have to compile them yourself so I can finally validate my already running system.
I think the OpenXR-SDK repository should contain the API validation layers source and the readme/build instructions should reference it. It is very easy to miss and they could have been really handy a week ago when I was debugging.
