Hi cgdvs,
Between v0.16128 and v1.005 some Alembic export stuff changed, but it was actually changed in a way that fixed some bugs which enabled Alembic export to be compatible with Cinema4D. So VRay no longer reading the color channel correctly is actually a VRay bug***, not a tyFlow bug, likely due to an improper data import implementation. This can be confirmed by loading the Alembic file in the official Alembic Viewer (ABCView) and seeing that the color data is indeed there. Obviously knowing that information doesn't help you in this scenario, but at least it's an explanation for what's going on.
I guess the only solution here, that doesn't involve Chaos Group fixing their importer, is for me to revert my code. But I don't think reverting my code to a past version (which was broken and only worked with VRay Proxy through sheer coincidence) is a good idea. I would suggest loading your particles in a different way that doesn't involve VRay Proxies, or sticking with the old tyFlow beta version as your exporter.
*** on further investigation, it's not necessarily a 'bug', it's just that VRay follows the Houdini convention of expecting secondary params to be within the 'arbGeomParams' container rather than the same container as pos/velocity/id/size.
Between v0.16128 and v1.005 some Alembic export stuff changed, but it was actually changed in a way that fixed some bugs which enabled Alembic export to be compatible with Cinema4D. So VRay no longer reading the color channel correctly is actually a VRay bug***, not a tyFlow bug, likely due to an improper data import implementation. This can be confirmed by loading the Alembic file in the official Alembic Viewer (ABCView) and seeing that the color data is indeed there. Obviously knowing that information doesn't help you in this scenario, but at least it's an explanation for what's going on.
I guess the only solution here, that doesn't involve Chaos Group fixing their importer, is for me to revert my code. But I don't think reverting my code to a past version (which was broken and only worked with VRay Proxy through sheer coincidence) is a good idea. I would suggest loading your particles in a different way that doesn't involve VRay Proxies, or sticking with the old tyFlow beta version as your exporter.
*** on further investigation, it's not necessarily a 'bug', it's just that VRay follows the Houdini convention of expecting secondary params to be within the 'arbGeomParams' container rather than the same container as pos/velocity/id/size.