Hi,
I have a cache of particles that has been simmed in the centre of my scene. It is a simple particle SIM with particles flowing along the Z axis.

I would like to instance that cache with a time offset on the points of a circle that is spinning.

I am using the Delay Load Procedural to read in the cache at render time. The question is this:

I strongly believe that I need to fix my “v” vector before the cache is passed to the renderer as the transformation is irrelevant to the actual SIM position. So I believe that I need to find a way of passing a matrix attribute from my instance points, so I can update the my velocity vector before things get rendered, and no need to mention that I am using the velocity for the motion blur calculations.

Any idea about how to do that?

Thanks.

Well, it seems like things are slightly more complicated. I got various aspects of the instancing to work, but could not make the CVEX actually do anything. As a starters I am trying to manipulate “P” in some simple fashion, but even that seems to be doing nothing. Is there something special that needs to be done in order to get CVEX working?

Thanks.

I do not seem to be able to get anything into the CVEX context under 12.5, it seems to be totally broken. Under 12.0, I can print “P”, “v” etc. anything coming into there, but in 12.5, the print returns nothing.

I have been trying many different instancing approaches, they kind of work to get colour and time variations but the CVEX context proves to be useless at this point. I am aware that you can manipulate only translations, but … nothing seems to be working when it comes to CVEX.

What do Support say , have you emailed them ? , I would have a dig around but I am on H12 :cry:

Rob

Hi,
Well, it was mostly my mistake (as usual). I forgot some instancing related render properties on the object level geo node that I was rendering so they were cutting off the procedural shaders and were doing a “point inctancing” instead of “procedural instancing”. So now things are better.

Thanks.

Hi,
I have been playing around with INSTACING and CVEX. I came accross the following problem:

If I have a “v” attribute inside my cache that I am instancing on some points, I can manipulate the xform of the cache that is being instanced with CVEX and that also updates the “v” that is coming with the cache, however, it seems like it drops any motion blur that might have been caused by an animation on the actual points that we instance on.

Any ideas?

Thanks.

Interesting > but surely its only right that the cache motion blur is dropped if your transforming the points. Otherwise how would you create correct motion blur if your cache objects are lets assume moving in +Z while your points are transforming in -Z . Unless I am missing something. Have you contacted support ?

Rob

Sorry, not yet. Well, I was looking at this in the following way:
If you have a particle SIM flowing along the Z axis, you will get some velocity already in there. Lots of details, as it is a particle SIM.

Then you take that SIM, time offset it and instance it on 24 points on a circle, and spin that circle. You would expect to get some motion blur due to the fact that the entire thing is spinning, but then also maintain some of the internal motion blur resulting from the velocity of your particles.

For now, I think I have solved the problem by attaching my procedural delay load for the particles on to a container object and then doing the spinning at object level. This kind of gave me some promising results, at least the simple prototype. Tonight I will render the real thing and evaluate the results tomorrow. If things are still broken, I will then contact support.

Thanks.