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Mops and Pops orientation

Posted: Tue Sep 13, 2022 5:15 am
by CKx
Hi there me again!
I'm having a bit of a hard time trying to get my MOPS instances to orient in the direction of my particle velocity from a pop sim. I've tried a few things but no luck, maybe someone could tell me best practice here?

Re: Mops and Pops orientation

Posted: Tue Sep 13, 2022 11:53 am
by toadstorm
The MOPs Instancer doesn't automatically use velocity as the N or "forward" attribute when instancing to points. If you want your points to aim in the direction of motion, define a normal attribute from your velocity. You can do it really quickly with a Point Wrangle on your particles:

v@N = normalize(v@v);

This only defines a forward axis, though. Without a defined up axis, the instances are likely to flip around a bunch. I'd recommend also explicitly setting an up vector to reduce this:

v@up = {0,1,0};

You can do both these operations in the same point wrangle. Also, don't forget to uncheck "Enable Template Interpolation" on the MOPs Instancer, since your POP sim likely has a changing point count.

Re: Mops and Pops orientation

Posted: Thu Sep 15, 2022 2:04 am
by CKx
thanks so much, I was trying various bits of vex but couldn't crack it, most appreciated.