Merge pull request #1083 from danrbailey/tsc20210601

Meeting notes 1st June

Author: danrbailey

tsc/meetings/2021-06-01.md

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+Minutes from 93rd OpenVDB TSC meeting, June 1st, 2021, (EDT)
+
+Attendees: *Nick* A., *Jeff* L., *Dan* B., *Andre* P.
+
+Additional Attendees: JT Nelson (Blender), Richard Jones (DNeg),
+Johannes Meng (Intel)
+
+Regrets: *Ken* M.
+
+Agenda:
+
+1) Confirm Quorum
+2) Secretary
+3) Context functions in VDB AX
+4) VDB Vector Merge
+5) VDB 8.1.0
+6) Feedback from Larry
+7) Siggraph Course
+8) Next meeting
+
+
+1) Confirm Quorum
+
+Quorum is present.
+
+2) Secretary
+
+Secretary is Dan Bailey.
+
+3) Context functions in VDB AX
+
+Nick presented some options for introducing "context functions". The backend is
+working in AX, but the syntax has not yet been agreed upon. There are issues
+with using free functions related to type inference in particular. For example,
+"@density = volumesample()" needs to know the type of the volume being sampled.
+Jeff mentions that VEX has support for return type overloads such as with the
+point() function, however a specific choice was made to use volumesample and
+volumesamplev to avoid the challenge of trying to infer the type in a nested
+expression. An example of this is 5.0 * noise(...) - it's not clear if this is
+intended to be 1D or 3D noise.
+
+Nick wants the user to be able to select the context for two reasons. One to be
+able to seamlessly transfer code from one context with another without having to
+rewrite the snippet and two to be to use multi-context snippets, such as
+sampling a volume onto a point attribute. Jeff highly values the first point.
+Additional contexts being considered are a "metadata" context and a "generic"
+context.
+
+Various options were discussed, and the leading candidate came out to be this
+one:
+
+volume::@density->sample()
+
+With the ability to assume default context by dropping the "namespace":
+
+@density->sample()
+
+One additional complexity is being able to retrieve the transform from the
+volume associated with a point attribute, Rich gave this example:
+
+volume::pt@density->transform()
+
+Not ideal, but ideally would like the user not to need to know the name of the
+point grid to access the transform.
+
+Nick and Rich to look into issues related to this discussion and come back with
+a more concrete proposal.
+
+4) VDB Vector Merge
+
+Proposal to rename this SOP to 'VDB Vector from Scalar' to avoid confusion with
+the VDB Merge SOP which performs a very different operation. Will change just
+the label name and not the operator type name.
+
+Possibility to also rename 'VDB Vector Split' to 'VDB Scalar from Vector', but
+this has the added confusion of sounding like it might compute the length of a
+vector rather than splitting out each component.
+
+Decision was to go ahead with the 'VDB Vector Merge' -> 'VDB Vector from Scalar'
+rename and leave the 'VDB Vector Split'. Jeff has made the change in Houdini. No
+change to the core library so not deemed urgent to rush it into the 8.1.0
+release.
+
+5) VDB 8.1.0
+
+A few minor fixes to be introduced to the release candidate. Nick to merge
+master into this branch. Otherwise, VDB 8.1.0 is ready for release.
+
+6) Feedback from Larry
+
+Which version of VDB was the feature/nanovdb branched from? Decision was to try
+and merge master into this feature branch on a more regular basis so that there
+are fewer differences between the two branches.
+
+Can OpenVDB be built against OpenEXR 3.0? Has not been tested currently. This
+will affect the core library (for Half) and the openvdb_render binary (for
+OpenEXR). Decision to test this and to update the embedded version of Half now
+that this version has been released.
+
+7) Siggraph Course
+
+JT will have a draft edit ready by Wednesday morning, a few minor changes needed
+and the final slide. Submission deadline is Friday 4th June.
+
+Submission deadline for course notes is the following week - Friday 11th June.
+Course notes to be discussed in next weeks TSC meeting.
+
+8) Next meeting
+
+Next meeting is June 8th, 2021. 12pm-1pm EST (GMT-5).