awong

lucavfx
I followed your instructions to the letter, the nparticles cache is created on disk,
however upon attaching the nparticles cache to the duplicated nparticles transform node nothing appears when scrubbing in the viewport. I get the following warning I suspect might be related:

// Warning: file: CProgram Files/Autodesk/Maya2018/scripts/others/doImportCacheFile.mel line 99: Channel names did not match selected objects. Using channel houdini_engine_particles_v0011_0Shape_id on object houdini_engine_particles_v0011_1Shape. //

Hm, here are a few things I can think of that you can check/try:

1. Take a look at the cached files, and make sure the file sizes do look like sensible. For example, the file size shouldn't be too small (less than a few kilobytes would be too small).

2. Before exporting the cache, do a sync to make sure the nParticle node has the exact same set of per-particle attributes that your asset is outputting. There might be issue if your asset is actually outputting less attributes than your nParticle is expecting. Otherwise, the nParticle node would have attributes with no data, and I'm not sure how nCache would react to that.

3. I wonder if some per-particle attributes are causing issues during nCache export. The simple way to test this is to try removing all the point attributes in the asset itself. This means the particle should have no other attributes except P. Then, in Maya, redo the sync, export cache, and attach cache steps. If this works, then there's likely some attributes on the particle that's causing issues with nCache.

4. If there's no particles in the beginning of the simulation, try exporting the cache from a frame that has particles. (I don't expect this to be an issue, but worth trying just to be sure.)

“Use Asset Object Transform” is probably only useful when the asset is an Object asset. An Object asset has its own world transform, which isn't exported to Maya by default. Enabling that option will export the Object transform into Maya.

In the case of a SOP asset, Houdini Engine creates a dummy Object node, and puts the SOP asset inside. However, this Object node is always at identity. So when this transform is exported to Maya, the asset looks like it's always at zero.

I see your geometry has the “shop_materialpath”. There was a performance bug when outputting string attributes. This was fixed in 16.0.785 or later. You could test if this is the issue by deleting the “shop_materialpath” attribute in the asset, and see if there's any speed difference.

Another potential slowdown is when the output geometry from the asset tries to preserve the input Maya geometry's locked/unlocked normals and soft/hard edges. I don't know if this is happening in your case, because this depends on the input geometry from Maya. You could test this by deleting the “maya_hard_edge” and “maya_locked_normal” vertex attribute in the asset.