Does the wind simulator have an effect on particles?

[Hugging_Bear]

Hi guys,
I'm building an autumn/fall scene in Moho. An increasing wind is moving the branches of a tree [youtube]https://youtu.be/2sVZYnWgPOk[/youtube]
As you can see the leaves (particle layer) move nearly horizontal to the right, while the setting is 270 (straight down).
I want the leaves to start falling leisurely and vertical. As the wind picks up, I want them to 'blow' faster and more horizontal. I planned to achieve that by creating a series of particle layers which I active as the story develops.

Somehow the wind parameters seems to have an effect on the particles (leaves) which shouldn't happen because they are on two separate layers.
Any suggestions?

Your help is very much appreciated!

PS: I've just isolated the particle layers in a project file of their own. Their odd behavior continues. I guess, I have to set all parameters back to zero and to (re)start experimenting with each parameter

[Greenlaw]

TBH, I had yet to try the the new wind dynamics and this seemed like a good exercise to check it out with. Here's what I put together...



Here's the project file if you'd like to pick it apart...

leaves.zip

I'm not sure why the wind is affecting your particles. I didn't see it happening in my example, but just to be sure I used Bind Layer for Particle group to bind it to a root bone to prevent other 'wind' bones from affecting anything inside the group. I'm not sure this was necessary but you might give it a try.

If you have any questions about this project file or particles and bone dynamics in general, feel free to ask.

[Greenlaw]

Re: direction, I have Direction set to 0 degrees and the Spread set to 45 degrees. This makes the leaves move to the right and spread in a 45 degree range.

To make the leaves fall, I set the Acceleration to around 340 degrees and the rate or 0.25. This makes the leaves gradually drift downward.

Also note that the Velocity and Velocity Spread are set fairly low. This is you initial speed and setting it low makes the effect look like a normal windy day and less like a hurricane.

Tip: ramp up the leaf sprite's opacity...this makes the appearance of a particle look smoother and less distracting. I think this is preferable to seeing them pop-on out of nowhere.

Hope this helps.

[Greenlaw]

BTW, I just realized I did the opposite of what you requested: You want the leaves to fall downward and then get caught by the wind and move to the right; in my example, they move to the right and then drift downward.

I believe what I animated may be closer to what actually happens on a windy day, but I think you can achieve what you want by changing some of the values I explained above.

[Greenlaw]

Here's another trick you might want to try to change wind direction...



Here's what I did: The project file is the same one and I wanted to use a mesh warp to swoop the leaves upward. Moho's mesh warp cannot deform particles but if you pre-render the particle layer to an image sequence (using Layer Comps and Moho Exporter,) you can import that image sequence and use a mesh warp on that.


This the kind of thing I do in compositing programs like AE, Fusion or Nuke for 3D sims all the time...it's often easier to alter your animation in post than to fight a physics system to make it do exactly what you want.

[MrMiracle77]

Check the 'acceleration' direction and value of the particle layer.

With a value of 0, the particles will go in a straight direction.

With a direction the same as the speed direction, the particles will accelerate from their generation point to higher speeds.

With a direction opposite the speed direction, the particles will emit, come to a stop, and reverse direction.

What you may want is an acceleration perpendicular to the emission direction.

[chucky]

I think particles could do with a bettrr directional arrow...more like the wind's one.
Saving presets of particle settings and the option to to key settings would be awesome too.

[Greenlaw]

Yeah, I'd like to see Moho get an update to its particle system. It's capable of a lot of fun/cool stuff but I often use Trapcode Particular in After Effects instead because it's capable of so much more. Particular is certainly overkill for most Moho users but I wish Moho had more of Particular's 'basic' features to make it easier and more predictable to use.

[Greenlaw]

I fiddled around with the particle settings in another project to see if I could get the particles to fall vertically from above and then lift up to the right...



I see that it can done but my setup is not ideal. I had to use higher velocity to force the particles downward and then dampen them to slow them down enough for the Acceleration to change their direction. This means these stars are falling faster than the gentle leaves in my earlier test example. Like so...



Way too fast.

The stars can probably be slowed down with some adjustment but I think this is a case of forcing the system to do something it's not designed for. (If this had been a real task for me, I'd have switched over to using Particular in Ae by now.)

I'm curious to see if anybody can get Moho the particles to work the way Hugging_Bear wants. I think it's possible but I can't spend any more time on this. Here's the project file...

starfall.moho

It would be cool if Moho had effector objects that could be used to change the behavior of the particles as they drifted into them. (i.e., Wind effector, Forcefield, Attract, Turbulence, etc.)

[synthsin75]

I'd start by binding the particle layer/s to one or more bones. The wind affecting those bones would then control the particle direction.
As far as getting a particle to go from a gentle motion to a faster, blown motion, I'd just use two different particles and switch the first off as the second one starts. With a little on/off overlap, you can't really tell the transition.

[chucky]

Yeah you can use paths in sorts of layered ways to hack Moho's particles a bit, can't go into detail right now.
You can also bind paths to bones and move them, eventually though it all falls apart.
Also the particle preview has been broken since V12 which is so painful to use. Ugh

Normally the best trick is to actually animate the layer of the leaf to 'oscillate' and give variety.
Just play with it.

[synthsin75]

Also the particle preview has been broken since V12 which is so painful to use. Ugh

I've found that playing the timeline from frame one seems to give fairly consistent results in the workspace. If you're working further down the timeline, set your start frame closer and play from there.

[Greenlaw]

That reminds me: one 'basic' features in Trapcode Particular that I'd like to see replicated in Moho Particles is the Over Life curve. This is a curve available in particle properties that controls that property over the lifespan of a particle, for example Color Over Life, Opacity Over Life, Size Over Life. There is even a Velocity Over Life curve so you can speed up or slow down a particle as it ages, which would address the speed issue.

I was able to control 'opacity over life' in Moho leaf particle in the above example by directly animating the sprite, but I can't do this for velocity. Velocity Over Life would do that.

[Greenlaw]

The other day I was going to try a 'fake' particle test using the Scatter Brush and Follow Path but I thought I was seeing a new bug with the tool.

1. Select and copy the leaf sprite.
2. Choose Clipboard as your source for the Scatter Brush. Set the Fill and Stroke to 0 but leave Angle set to 90.
3. Draw with the tool. Angle is broken.

Even now I'm not seeing any random rotation, just the leaf repeated with the same orientation.

This made me think using Clipboard as a source was broken and I was preparing to report it. However, in further testing, this option works fine when I create a brand new sprite in another layer and use that as the Scatter Brush source. it even works with the same leaf drawing but only when I copy that into a new project. Now I'm thinking the feature is fine but there's possibly a little internal corruption in my project file, or maybe the keyframe animation is somehow interfering.

It's not serious but I was wondering if anybody else is seeing this error with the project I posted?

[Greenlaw]

That reminds me, there really should be a Scale Jitter option for the Scatter Brush tool.