Bobo,
I’m making a comet, a tumbling rock with particles being left behind. It’s looking great. However, comets have more than one tail. The second is usually pointing away from the sun, not the direction of travel. I was wondering if you could help me figure out a way to take the first sim and “skew” it to make the second tail without re simulating anything. It seems like it would have to be skewed in a direction based on the life of the particle so that the particles still emit from the moving rock. Sounds easy for you, and lots of trial and error for me.
Any ideas?
Fred
I thought you were joking when you said it were easy for me, but I tried it and the first thing I did worked 
But since I am using a newer build of Krakatoa you don’t have, I now have to revert back to an older build to prepare the scene for you. Give me half an hour and I will upload my solution…
KMX2_Comet_Max2010_v002.zip (25.8 KB)
Ok, here is what I did:
*I created a sphere and animated it to move like a rock in space
*I emitted a trail with PFlow with Delete set to default 60 +/-10
*I saved the trail to PRT files incl. Age and LifeSpan
*I then loaded the sequence in a PRT Loader and cloned it a second time as a copy
*I added a Magma modifier and performed the following:
-Transform the particle Position into object space of the sphere (this brings the origin to the pivot of the sphere)
-Rotate the Position using the TransformByQuat operator and a QuatFromAngleAndAxis BLOP. This performs a “bend” at a given angle about a given axis
-The Axis was set to 0,0,1 and the Angle was set to a Base angle plus a Bend amount multiplied by 1.0-(Age/LifeSpan) .
*Once the particle was rotated, it was transformed back from the coordinate space of the sphere to the local object space and output as Position.
KMX2_Comet_TrailSkew_Magma_v002.png
To use the attached file, you must first create the PRT sequence. Enable the PFlow and save with Krakatoa to PRT sequence. Then disable the PFlow and make sure the two PRT Loaders are pointing at the newly saved particles.
In my example, I rotated at 50 degrees Base and bent at 40 more, so in the beginning it goes out at 90 degrees, then bends to 50 before dying.
This is what I see in my viewport on frame 90:
This does not rotate the Velocity vector, but it might not be necessary. If it is, the same method applies, but the Transform should be in a different mode (Vector instead of Point).
If this is not the effect you wanted, at least I hope it gives you a good direction to follow…
SEE! I knew youd be able to pull this off with little effort. I need the second trail to not bend at all, but ill take a look at what you did and see if i can tweak it.
Thanks- you rock!
Any chance you can kick out a 2011 version? (Im assuming its not loading since its 2013?)
My bad. I saved a 2010 scene, but zipped the wrong one (2013). I have replaced the zip in the original post.
Thanks!
My setup supports both straight and bent trail - just enter 0 for the SkewAngle and any angle in the BaseAngle and you will get the just Base rotation without the additional curvature by age.
Since you mentioned something about Age I assumed you wanted to change the degree based on it…
I’m not seeing a new version in the original post. You might need to repost it. Whats weird is I loaded it in 2013 and saved back to 2011 and the magma flow doesn’t open at all? Perhaps we found a bug along the way?
Sounds like a bug that was fixed long ago.
What version of Krakatoa are you running? It should not happen in 2.1.x…
Basically, Autodesk forgot to handle Unicode when converting AppData strings between versions. So moving data back to 2010 and 2011 can cause some settings of the Magma editor to get corrupted.
I added code to handle that at some point, but it sounds like it is not kicking in in your case.
You can save the Flow itself out of 2013 and load it in 2011 on a new modifier.