This was posted to another list recently…
If anyone happened to be in a studio in the early 00s and heard of the Temerity pipeline, parts of PDG might feel a little familiar (minus the version control). It's been open sourced:
https://github.com/JimCallahan/Pipeline [github.com]
Manual is here:
https://github.com/JimCallahan/Pipeline/blob/master/docs/manuals/PipelineManual.pdf [github.com]