Clarify the use of `XrPassthroughHTC` handles

[yshui]

Two questions I have:

1. can multiple XrPassthroughHTC handles created from a single XrSession exist at the same time?
2. can multiple XrCompositionLayerPassthroughHTC layers referencing the same XrPassthroughHTC handle exist in the same xrEndFrame call? if so is there a limit to how many such layers there can be?

The spec says (emphasis mine):

An application can create an XrPassthroughHTC handle by calling xrCreatePassthroughHTC.

If I take this "an" as face value, this seems to state only one such handle may be created? similarly:

The application can create an XrCompositionLayerPassthroughHTC structure with the created passthrough and the corresponding information. A pointer to XrCompositionLayerPassthroughHTC may be submitted in xrEndFrame

Is that the correct reading?

[rpavlik-bot]

An issue (number 2501) has been filed to correspond to this issue in the internal Khronos GitLab (Khronos members only: KHR:openxr/openxr#2501 ), to facilitate working group processes.

This GitHub issue will continue to be the main site of discussion.