houdini 12.5 smoke-local velocity emission bug?

[Waasha]

Hello everyone!

I have a question about local transformations when emitting smoke in H12.5.

I created a cylinder oriented on Z axis, I rotated it 45 degrees around Y and I made it emit smoke.

I wanted it to emit the smoke in the direction of its local X axis, so I added velocity along X, visualize the streamers (the streamers's direction looks perfectly OK) and run the sim...

The outcome is on the picture:

As you can see, houdini ignored the local axis of the object and emits the velocity in the WORLD X axis....

The same thing happens when I use the empty geometry and object merge with transform set "into this object" and then make it a smoke source...

Can anyone tell me what am I missing? I can't find any simple way to tackle this...

I have a workaround involving reading the normal of one polygon and then, using attribute transfer I feed the N channel to V and it is working, but it's COMPLICATED, I cannot believe there isn't any other (simple) way to emit smoke with velocity in the direction of emittor's local axis...

Any help MUCH appretiated!

[anim]

the streamers is geometry generated from the vel data and then transformed by object transform therefore it looks correct, however the vel data itself is not transformed

I would not call it a bug rather something that developers forgot to implement to reflect the same behavior as vector geometry attributes

so you can either transform the data yourself as it was already discussed here (includes example)

http://forums.odforc...ta/#entry106888

or use source relationship to emit along local axis

which will be faster since you don't have to recompute volumes each timestep

example here

local_axis_emission.hip

Edited May 21, 2013 by anim