Tomas Slancik


About Me

Advertising / Motion Graphics


New York, United States

Houdini Skills


I am currently employed at Method Studios

Recent Forum Posts

Retiming value clip instances Feb. 23, 2024, 1:32 p.m.

I may be pushing back on this harder than is absolutely necessary, but I see a lot of people think they need value clips when they really don't, but they dive into the value clip rabbit hole anyway and learn that value clips don't make anything easier. They make everything harder. When you need them, you need them. But when you don't need them, don't use them.

Houdini historically has been used for simulation where 99% of the caches are .bgeo* or .vdb sequence
Houdini also has very convenient way to load those as PAcked Disk Sequence, copy around and retime using index intrinsic, and it automatically can interpolate geos with the same topology (between indices) or not when the topology differs
and also provides extrapolation options out of range

Users just want the same ease of use and flexibility when using Solaris and USD
From what I understood Value Clips should provide the way to reference such .bgeo* sequences and provide interpolation and extrapolation options, not sure about the behavior with different topology
So naturally everyone will first reach for Value Clips and try to see if it's easy to offset them per instance, because having to export a cache again as a single .usd is a waste of time and space regardless of how big the cache is

I'd be great if Sidefx could provide a proper way to do very essential workflows witin Solaris to avoid users trying to come up with workarounds that are not considered optimal

Would it be possible to have SOP Import LOP recognize Packed Disk Sequence primitives and create a proper USD way of reference to those referenced files that is offsettable, interpolates for same topo and not for different and has out of frame extrapolation without extra intermediate caches or workarounds?
That way it would take away the guess work, because while I don't use USD yet so far 100% of the people I asked the same question if this is easy or even possible to do in USD or solaris said that they don't know

RBD+FLIP Feb. 22, 2024, 11:49 p.m.

Thank you very much for the precious tips Tomas.
May i ask you more details about this?
- or use separate collision separation that will capture the resolution of your pieces
FLIP Object DOP/Properties/Collision Separation can be enabled and set to smaller (or larger) grid scale than other grids whose grid scale is Particle Separation * Grid Scale

therefore you can have lower res FLIP sim, but still have it consider higher resolution collision grid which would see more of your small colliders and can provide feedback to them

Simple retime with foreach Feb. 22, 2024, 3:23 p.m.

Thanks for the feedback!

It does work if I use with "fetch as input" but it wont loop per line time shift just affects everything the same.
You can use Blast sop based in iteration metadata to keep the correct piece, but the key is to use non cached Fetch As Input