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I'm new to popcorn and vfx in general but know my way around the UE editor.

When I'm importing a sample effect (say from GDC2015 project) - I have set the fx editor so it's the right co-ordinate system for UE (Axis_LeftHand_Z_Up) but don't know how to rotate the sample effect so it orients correctly. I have done it for a fairly simple effect - Environment/Rain by going into the Raindrops physics property and swapping y and z values , changing emitter box size and orientation etc but am wondering if there's an easier way?

Is there a way to rotate an entire effect tree either in the Popcorn Editor or once the effect has been brought into UE? Or is it fixed to the individual parameters used for each element in the effect tree? Basically what's the process for going about rotating or translating an effect and placing it correctly in Unreal Engine?

Popcorn FX is amazing by the way! New to it but can't wait to get heavily into it and creating some awesome vfx!


by Sean (270 points)

1 Answer

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Hi Sean,

Thanks for the kind words.

Like you point out, you will have to do that on a per effect basis in each node (script/sampler/physics evolver/..) that has an axis dependant behavior. Unfortunately there is no easy way to quick fix that.

However a good thing to keep in mind when creating effect is making sure they are axis independant by using script functions like float3suf and others. See here: http://wiki.popcornfx.com/index.php/UE4/Troubleshooting#My_particles_are_not_oriented_correctly

By the time we released the GDC15 pack, this isn't something we had in mind when publishing all those effects and it make it painful to port them to UE4 right now, but depending on the effect's complexity it should be pretty fast to fix :)

Keep an eye for :

  • Shape samplers orientation/position
  • Scripts float3() constructions
  • Physics evolver constant acceleration
  • ..


by HugoPKFX (17.7k points)
Cool, that makes sense, just wanted to check.
It's a good learning exercise converting the GDC examples I want to try anyway :)