On the export of vertex color from ABC point cloud

[cgdvs]

HI，Tyson!
After repeated testing, I found "export particles" in the new version_ Alembic point cloud cannot enter vertex color. There is no problem in the old version. (this file is tested in tyflow 0.16128, and the effect is correct).

[tyFlow]

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.

[cgdvs]

I believe you are right.
But I also invited friends of Houdini platform to test the two files respectively. The point cloud file exported in the new version of tyflow cannot correctly detect the "vertex color" channel in Houdini
Tyflow0 The output file of 16128 version is Vray recognized, and the "vertex color" channel can also be read in Houdini. I'm not sure how C4d works, but it doesn't seem to be the point to work correctly in C4d, right?
So if you don't want to go back to the old version, can you add the "color" channel in the old version to the new version? Of course, this is just my proposal. I don't know whether it is feasible or not. I just hope you can reconsider. thank you

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Vray proxy mode is a good choice because it can render exported particles. If I export PRT format instead, this format can only be rendered with the "KK" renderer. The problem with the "KK" renderer is that it cannot render reflections, refractions and so on. However, point clouds can be rendered under the Vray renderer. In some cases, more colors need to be added. Therefore, point cloud is also a very important workflow. Although it can better support C4d, it makes no sense to us, even reducing sub items. Because it lost more

[tyFlow]

Hi cgdvs,

The data is all there. However, looking at this thread:

https://www.sidefx.com/forum/topic/41947...ost-188415

It seems Houdini specifically expects to find it under 'arbGeomParams', which is unfortunately just an arbitrary Houdini convention rather than something that makes sense within the Alembic format.

I believe it should still be possible to access the params in the modified format since I had a Houdini user specifically request that it not go within 'arbGeomParams'. However, I don't know Houdini and don't know how that user was accessing the extra params, so I can't offer you any advice in that regard.

It's unfortunate that Alembic is such a disjointed format, with no real official standards that I'm aware of and many different ways to do the same thing (Maya, Max, Houdini, C4D all load Alembic in different ways and support different features of it in different ways, and for that reason it's a very annoying format to work with)...however, I will add an option in the next build to support 'arbGeomParams' again so that the data can be loaded in the same way as before.

[tyFlow]

Ok I've implemented the format switch. It seems compatible with the VRay Proxy loader again now too. If you would like access to an early build, just email me which version of Max you need it for and I'll send it to you.

[cgdvs]

Hi!
If tycache can render particles in the future, I think "abc_point cloud" will no longer make sense.
As a special effects personnel of Max users, I look forward to having different solutions.
Oh, by the way, I have all the early versions here. If the new version is compatible again, I would be grateful.
I appreciate your patience and help. I hope it doesn't bother you.

[tyFlow]

Whoops, what I mean by "early build" is "an early build of the next version" (ie, v1.006). In other words, I can send you a version of tyFlow v1.006 with the format switch implemented, so that you can load your exported point caches in Houdini/VRay again, without losing any data. I just need to know which version of Max you need it for, so please email me that detail if you'd like the fix.

[cgdvs]

Ha ha, thank you very much.