Motion Paths, Trapcode Particular, & 3D space, OH MY!

[Simon Stutts]

You could have a 3d null object follow your designated course, then parent the motion of the particle emitter & the object to the null. To get the xyz position of the emitter to follow the null, set the emitter to be a light, then parent the light to the null object.

[Kevin Camp]

it’s not too hard to do, but it’s a little hard to explain… i think it will be easiest to explain if you apply the ‘separate xyz position’ to the layer that will track the emitter.

then you’d need to select each of the separate xyz effect’s properties (x, y, and z) and choose animation>add expression. grab the expression pick whip for the z property (of ‘separate xyz’) and drag it to the z property of your emitter.

do the same for the x property, linking it to the emitter’s x,y postion, but at the end of the expression type [0] (that’s open bracket-zero-closed bracket). do the same for the y property, but add [1] to the end of the expression.

once done the layer should follow the emitter. the same could be applied to a 3d null or light as simon suggests, then parent your 3d layer to the null/light.

Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW

[Creighton Matthews]

Would you mind explaining how to separate the x, y, and z position dialogs? I didn’t know that could be done. If I can do that, the rest should be gravy. Thanks a lot!

-Creighton

[Travis Roop]

watch this tut.

https://library.creativecow.net/articles/rabinowitz_aharon/red_giant_emitter_position.php

Travis Roop
Editor
bitMAX Hollywood
troop@bitmax.net

[Mike Park]

I am not exactly sure of what you are trying to do, but let me take a stab. You want to have the emitter of your Particular layer follow something in 3d space but cant figure out how to link it because Particular seperates the xy and z emitter coordinates. If you picwip the particular xy emitter position to the 3d object position you want to track, it will write an expression for xy only using [0] and [1] which are xy. Then picwip the z emitter position from particular and place your cursor over the z position only of the 3d object. Do not like to the position name, but to the actual z position. This will write an expression using z only or [2]. Most of the time, I picwip to a 3d null object because it is easier to manipulate, but this will work fine, as long as I understood your question correctly.

Best of luck

[Creighton Matthews]

I got it folks! Thanks for all of the suggestions. I animated my emitter in Particular and wanted something to follow that (hard). All I needed to do was animate a null and have my emitter follow that (easy). I’m actually a little embarrassed that I didn’t think of that in the first place, but I already had my emitter animated. Oh well… Thanks a ton!

Creighton

[Kevin Camp]

yep, it would have been simpler to start that way..

to answer your earlier question, the separate xyz positions is an effects preset… from the effects & presets panel choose animation presets>transform>separate xyz positions (or type ‘separate’ in the ‘contains’ field). it can be pretty handy, but you can do the same things with expressions…

Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW

[Francisco Cueto]

and a follow up on this one since they are sooo similar & yet not quite…

first time poster, long time lurker…

I am trying to animate an emitter going up that is about 1/3 from the left margin. I want this emitter to spin as it goes up, to kinda draw like a xmas tree.

In 3D packages I would animate a NULL going up, then place another null off to the side (the distance between them defines my radius) as the first null goes up I also rotate it about the Y axis and VOILA, the null that’s sitting to the side starts climbing up in a spiral fashion. Then all I need is to animate the second null on its local X axis towards the first null, basically creating a spiral with a decreasing radius kind of thing that looks like a X-mass tree (at least its trajectory)

I tried this setup with particular but no luck. I followed all the tutorials I could and read the very recent thread about this, and I am stumped. It seems that since I am using Parenting, the animation info is not passed along via the expression pick-whip method.

any clues how to go about this? I really dont want to open up the 3d app today 🙁

[Mike Park]

You are correct, parenting will not work. You can see this by using 2 null objects and parenting one to the other spin one and the xyz position of the second null doesnt change in the rollout, even though it looks like it does in the comp window.

To do this properly, you must use (gasp -) some math. Remember your old trig days. You just need to use the good ole sin and cos functions to create a circular path for the emitter to follow in x, z space, and then animate a variable for the radius. Then animate the y (or up) position of the emitter and there you have it. Somewhat of a pain, I know, but it works. I feel your pain regarding the difference in parenting in 3d apps like Max and AFX. I think every application has things we like and dislike.

Hope this helps. If you need some more specifics about circular functions in after effects, check out Dan Ebberts page on expressions. He lurks here on the Cow forums, but also has his own expression’s website. Just google his name and you will find it.

Best of luck

[Kevin Camp]

you could use some layer space transform expressions to convert the parented null’s position to the comp’s space, then back to the particular layer’s to track the null… that sounds a lot more complicated than it is…

try this expression in the emitters xy position:

target = thisComp.layer(“Null 2”); // use the pick whip to select the layer to track
fromComp(target.toComp(target.anchorPoint))

this was also from dan ebbert’s site, from the 3d corner pin example

Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW