Hello.
New to houdini indie

I try to trail a sphere animated in maya.

So, I build a digital asset in houdini.It does not work because the trail just recognize the transform node in houdini.

In addition,I try the objectMerge node and enter “.” to import the geometry using the transforms from the source object.The asset works fine in houdini, but not in maya.

How can I make it work?

Thank you very much.

This is actually a known problem. The trail SOP is hitting a limitation in Houdini Engine. The problem is that during a cook, Houdini Engine only has access to current frame's geometry. This means that when the trail SOP tries to get the geometry for the previous or next frame, the geometry will always be the same as the current frame.

This limitation can be worked around somewhat by using the cache SOP. The idea is to use the cache SOP to cache the input geometry at different frames. This can be done by attaching the cache SOP right after the input geometry. The input geometry will then be cached by playing through the timeline once. Once the geometries is cached, the trail SOP will have access to the correct geometries for different frames, and produce the right output.

See the attached asset and Maya scene.

Yes,it works.
Thank U

Hey Andrew,

This doesn't seem to work with cluster handle deforms… any way of handling something like this?

I've attached the Maya file (2014 service pack 2 P16).

Hm, what I see is that the cluster deform is being applied twice. Once to the input geo, and then once again to the output geo. This results in some kind of double deformation. This is definitely a bug. Is this what you mean by “not working”?

If so, then it's actually possible to workaround the issue. This is happening because cluster creates some sets (tweakSet1 and cluster1Set). These sets are being inputted into the asset as groups. This is normally harmless. However, when these groups are being outputted back into Maya, for some reasons, Maya apply the cluster deformation again to the output geometry. So the workaround is to simply delete all the groups inside the asset, so that these groups aren't outputted back to Maya.

Otherwise, the trail does seem to work for me.

Ah, OK - thanks Andrew! that was it.

I just made a change that should fix the issue. Try out tomorrow's build (15.0.327).