X-particles rotation ignored

[Anonymous]

Hi,

I'm having X-particles emit one flat disc particle onto every polygon of an animated plane, to which it is stuck and moves with the animation. It's supposed to look something like sequin on fabric. My whole setup works just fine except that when I use the approach of having Arnold generate the geo via an Arnold tag on the emitter it seems to ignore the rotation of the particles, leading to sequins poking through the surface. Is there any way to make it consider it?

As a backup solution I've tried generating the geo via xpGenerator and then they rotate correctly, but instead the colorization that comes from the planes texture is gone and all the sequins get a kind of pinkish color which I can't figure out where it's coming from.

Caching the particles doesn't help either unfortunately.

If anyone have any pointers on how to make either solution work it would be extremely appreciated!

[Anonymous]

It seems that Chris Schmidt has started a sequins revolution! I say, bring it on!

I've run into your exact issue in the past, and solved it the same way that you have, using the xpGenerator. This is not a perfect solution, especially when dealing with a large number of particles, but it does give you a lot of additional power over the scaling and rotation.

In an ideal world, I'd love to see Arnold acknowledge the rotation of particles when rendering with geo, and similar to the radius, I wish we had the ability to randomize the rotation within the Arnold Tag. X+ Arnold is so powerful, but there's a handful of gotchyas that make it frustrating to work with.

[peter.horvath6V6K3]

Can you send me a simple scene with your setup? I've checked the code and the instances are reading the transformation of the particles, so it should work. Made a quick test setting the rotation in Extended Data > General Data and it was showing fine.

[peter.horvath6V6K3]

If you have a list of improvements you'd like to see, please let me know.

[Anonymous]

Thank you @Peter Horvath and @Justin Marimon for the swift responses!

I'll attach a simple example scene showing how both the color and scale get passed through just fine, but the rotation is ignored it seems, or I have just missed something despite trying every single thing I could think of. If you can have a quick look Peter that would be just excellent!?

Sequin_Example.zip

[peter.horvath6V6K3]

When using the xpGenerator, you can read the color of the particles via a user_data_rgb shader. Set the attribute to display_color.

Can you show me how does the render look like with the xpGenerator vs the Arnold tag? Because for me they look very similar and the generator does not seem to be picking up the rotation either.

[Anonymous]

Hmm, I could have sworn that I had it working with xpGenerator last night but trying to recreate it now I can't seem to do it either. After testing further I'm pretty convinced I confused things last night and that it's an issue in XP and not Arnold at all. Using the display_color works great though, which will definitely come in handy, since I only thought that worked for Mograph. I apologize for bothering you with this Peter, and thanks again for the help!

[peter.horvath6V6K3]

No worries. If it turns out to be a problem with Arnold, just let me know.