MOPs Forums

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?

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.

thanks so much, I was trying various bits of vex but couldn't crack it, most appreciated.