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# Particluar, orient to motion issues

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 Particluar, orient to motion issues on Feb 15, 2013 at 5:06:40 pm

Hi Everyone,

Been a while since I've posted here but you lot are always so helpful.

I'm having trouble with particular, I'm trying to get the particles to orient to the motion but they just don't seem to respond. The emitter is parented to a null but I have tried it as a light or just animating the emitter, I've also tried custom particle sprite and polygon. I just can't seem to get it working.

http://imgur.com/zmCjT0J - a shot of my issue and settings.

Essentially I wanted the dashes to rotate so they follow the path, a data trail style affair.

Thanks for any help!

 Re: Particluar, orient to motion issueson Feb 15, 2013 at 8:01:04 pm

Ok, so here is the deal: What you are trying to do is rotate the particles in the direction of the emitter. Particular uses the vector motion of the particles themselves to orient them. Your particles have no velocity, therefore, no vector as a vector has both a direction and magnitude. Fortunately, I tackled this issue a couple years ago in a tutorial I did for Red Giant software. You can find that tutorial here: http://www.redgiantsoftware.com/videos/redgianttv/item/48/

It is a little math heavy, but it will get the job done. I seem to remember I did this in 2d, you may have to add some code to the z rotation to orient in 3d.

Hope this explains the issue and helps you solve it.

Best,

Mike Park

 Re: Particluar, orient to motion issueson Apr 16, 2013 at 2:39:13 pm

just found this thread. the script is great, and it would be helpful for a 2d application, but as Mike said, to get it to work in 3d space would require some more expressions. since im no expression master, i found that simply turning on orient to motion, and setting the emitter velocity, and velocity from motion both to 0.1 gives AE enough info to calculate the auto-orientation, no expressions required, and it works in 3d space.

glad i just figured this out, cause this always bothered me.

 Re: Particluar, orient to motion issuesby Jan Vorkon Sep 30, 2015 at 9:43:37 am

Hello Mark, I'm curious 'bout your solution, but unfortunately the tutorial is offline. Do you know where to find it? Thanks. Jay

http://www.jaydude.nl

 Re: Particluar, orient to motion issueson Sep 30, 2015 at 5:46:39 pm

Red Giant changed their format. Here is the new link.
http://www.redgiant.com/tutorial/episode-41-creating-a-stitch-effect-with-t...

 Re: Particluar, orient to motion issueson Apr 11, 2016 at 8:14:35 pm

Hi Mike
Thank you for your posts, they were very helpful. I wondered if you had any pointers about making this work for 3D.
Thanks
Ed

 Re: Particluar, orient to motion issueson Jun 26, 2016 at 1:23:40 am

Hello Mike!
Thanks a lot for your tutorial! It´s amazing! I´m working since weeks in a bigger design, and till now everything worked fine....but, there´s always a but...I´m trying to do a signifficant bigger comp, and the orientation went mad! I copied everything in a smaller comp, and it works fine, but when I start increasing the size, the curves of my paths seams to have an offset of 45º in the opposite direction. Any clue what could be happening here? Thanks a lot!

Eugenio

 Re: Particluar, orient to motion issueson Jun 26, 2016 at 6:27:49 am

Are you scaling the layer up in AE? My guess would be that the expression math doesn't take layer scaling into account. You could try and copy the original paths to Illustrator, scaling them there and then pasting back in. That might do the trick.

 Re: Particluar, orient to motion issueson Jun 26, 2016 at 11:58:22 am

Hi! Thanks a lot for your answer! I went thru the scaling issue before, but this time, I started from scratch. New comp. (8000 x 800), new null object, new solid on comp size, I just copied the expression and changed the name for the null. And that´s it! The path is a mask I drew with AE, nothing complicated, the complicated ones are already done! This one is just big! I tried cropping the comp and the solids, and suddenly everything works! But it´s a bit annoying tho work in pieces like a puzzle! Thanks again! I´ll keep trying

Eugenio

P.D. I´m a set designer that´s why I´m working in such a strange resolution, i just added all my screens. And I can´t scale everything because I want to go really close with a camera, so I need the resolution!
Thanks again!

Eugenio

 Re: Particluar, orient to motion issueson Jun 27, 2016 at 12:10:14 am

Hi again! I can confirm it, the bigger the comp is, bigger is the angel offset in the stitches..... any clue what is happening? Thanks!
Eugenio

 Re: Particluar, orient to motion issueson Jun 27, 2016 at 7:40:35 amLast Edited By Kalle Kannisto on Jun 27, 2016 at 7:42:26 am

Here's a different expression to try on the rotation value:

d = thisComp.layer("Null 1").transform.position.valueAtTime(time+1/100)-thisComp.layer("Null 1").transform.position;

This calculates the angle based on the actual position of the emitter a fraction later in time, rather than the speed at the current point.

Replace "Null 1" with the name of the null you're driving the emitter with.

The time offset "(time + 1/100)" should be a combination of your frame rate and the length of the stitch. I made it 100 as I had the frame rate of 50 fps with 50 particles per second and the stitch was 1/2 the length of the motion between frames. So, if you have a frame rate of 30 fps (and particles per second) and the stitch is 2/3 of the length of the distance between stitches, you'd use 30/(2/3) = 45, that is "(time + 1/45)". Or you can just try it until it looks right, in any case it should be equal or more than the particles per second.