Particles - how to make wavy lines like water

[AnjaFrey]

Hopefully someone can help: I tried to make water flow down a river. - and failed (using MOHOpro 12). The river is a sort of top view (like a snake, starting at the bottom of the monitor and ending in the top right corner) and I wanted to visualise the movement of the water with lines at right angles to the river bank. So I created a wavy line and multiplied it with a particle layer - but I don't think I understand the settings: what I was trying to achieve is several lines in sequence, like waves, one after the other, like a line or a ribbon. It always ends up with lines scattered everywhere. Does anyone have an idea how to set up the particle layer to do this? Or is there a tutorial out there on how to set particles like this?

[slowtiger]

I don't bother with particles in this case: I'd put lots of ripples lines on one layer about 3x the length of the visible river, move this layer with water speed, and put it into a mask which is the river. Can even do this with more than one in different speeds.

[Greenlaw]

@AnjaFrey

There are many possible ways to make water look like its flowing depending on the style and level or realism you want. Can you post an example (i.e., a link to a YouTube video, etc.) of what what you're trying to achieve?

Generally speaking, when river water is flowing, you're not so much seeing the moving surface, rather what you're actually seeing is how the motion affects is the reflection of the world/light source above the water, and if the water is clear, how it refracts ground under the water. You might see this In great detail in more realistic animations (i.e., Studio Ghibli's work,) but this information can be greatly simplified and abstracted for more cartoony styles and designs.

For example, you might use wavy line cyles to suggest the reflections bouncing off water, or maybe animate the water line along the bank. And if the water is clear and you're going for the more advanced look, a displacement effect can be applied over the ground beneath the surface to simulate the water refraction. For any of these, the wave should move in the direction and speed you imagine the water is flowing.

Note that the wave 'reflection' lines should not move down the river, but they should stay fixed in place. This is because the sky is obviously not moving, it's the moving water surface that's distorting reflection of the sky.

I'll assume you want a basic effect with flat colored water and make a few simple suggestions...

First, create a wavy line animation. Make it a cycle so copies of the wave can be offset. I suggest rendering this as an image sequence so Moho doesn't have calculate many copies of the wave. Next place copies of the line around the river surface. You might create multiple animation to make each one unique, or you can use Sequencer to offset their motions...or do both. You might even use a mesh warp to bend the copies to conform to the shape of the river or to simply make them look a little more distinct from each other.

Of course sometimes you may not want to go 'realistic' at all, and you just want those wavy lines flowing down the length of the river... this is a completely valid style. In this case, you can create a bunch of long wavy lines as a still image, and then slide this image through a mesh that's been deformed to fit the river's shape. If you make sure the ends of the drawing line up seamlessly, the river can flow infinitely as you slide the image through the warp. This is a really simple trick, requires very little work, and it can be very effective.

If I have time, I could whip up some examples but I think I'm going to be too busy today. If you can post some examples of what you're trying to create, maybe I can make more specific recommendations.

Hope this helps.

[Greenlaw]

Re: using particles for a river animation...that's an interesting approach. What I'm thinking about is probably not what you have in mind, but I've used particles to quickly populate a scene with many sprite instances of an element. So, in this case, the sprites can be the small wavy lines described above. I don't think Moho's particle system allows you to offset the sprite animation timing like, for example, Particular in Ae, but you should be able to duplicate the sprites in the particle group and offset them with sequencer. This will give you some variety without a lot of extra work.

You can't place where each particle goes but maybe you can fill a layer with the particles, and then warp and mask the layer to conform to the river shape. Depending on the angle we're viewing the river from, you can even angle the particle layer to cheat some perspective.

I'm not sure how practical any of this in Moho...I normally do this sort of thing in a compositing program like Ae, Fusion or Nuke. I think a simplified version of this can be done in Moho.

But, as slowtiger suggested, using particles is probably not the first thing I'd try for river animations, at least not in Moho.

[Greenlaw]

Re: Creating a wavy line animation, all I wrote was 'create a wavy line animation' and I just realized that's not particularly helpful.

There are many ways to do this, but one 'easy' way is to create a straight line with many points (you can do this manually or just use Hayasidist's handy shape creation tool,) and then apply [Scripts>Warp>Wave...] The only problem with this method is that it doesn't automatically make the animation cycle seamlessly so you may need to find a point where you can trim the animation to be close to cycling, and then tweak the points to smooth it out.

There may be other 'easy' way to do this in Moho but I'd have to think about it, and maybe just try a few to see what's quickest/easiest. Off the top of my head, you could push points with Magnet, or using Moho's FBF. or use a bone chain and Sketch bones. (I use this latter approach to make wavy lines all the time for rope, hair, etc. It can look very organic.)

In Ae, I would probably just slide a procedural or image-based texture to displace (warp) a drawing of lines. (It might be easier to create a cycle using a gradient image you created specifically for the displacement.) That's similar to using Wavy I guess, but without generating all the keyframes. Then I'd render the element as an image sequence and import it to Moho to use as a 'sprite'.

[AnjaFrey]

I don't bother with particles in this case: I'd put lots of ripples lines on one layer about 3x the length of the visible river, move this layer with water speed, and put it into a mask which is the river. Can even do this with more than one in different speeds.

Thank you very much! I will try your approach - and thank you for steering me in a new direction, I was really stuck.

[AnjaFrey]

@AnjaFrey

There are many possible ways to make water look like its flowing depending on the style and level or realism you want.
....
First, create a wavy line animation. Make it a cycle so copies of the wave can be offset. I suggest rendering this as an image sequence so Moho doesn't have calculate many copies of the wave. Next place copies of the line around the river surface. You might create multiple animation to make each one unique, or you can use Sequencer to offset their motions...or do both. You might even use a mesh warp to bend the copies to conform to the shape of the river or to simply make them look a little more distinct from each other.

Of course sometimes you may not want to go 'realistic' at all, and you just want those wavy lines flowing down the length of the river... this is a completely valid style. In this case, you can create a bunch of long wavy lines as a still image, and then slide this image through a mesh that's been deformed to fit the river's shape. If you make sure the ends of the drawing line up seamlessly, the river can flow infinitely as you slide the image through the warp. This is a really simple trick, requires very little work, and it can be very effective.

If I have time, I could whip up some examples but I think I'm going to be too busy today. If you can post some examples of what you're trying to create, maybe I can make more specific recommendations.

Hope this helps.

Thank you very much for your helpful answer! I very appreciate the ideas and insides on how water flowing represents itself - but yes, I am looking more for a basic effect here - but I definitely will keep it in mind. And I will try your 2 suggestions in the next days, also thank you for the tip with rendering an image sequence!

[AnjaFrey]

Re: using particles for a river animation...that's an interesting approach. ...

Yes, I won't try it again - I am now fully convinced that it is not an ideal approach (I use Apple Motion a lot, the particles there also have different and more possibilities, maybe that's why I thought of it in Moho).

[Greenlaw]

Yes, I won't try it again - I am now fully convinced that it is not an ideal approach (I use Apple Motion a lot, the particles there also have different and more possibilities, maybe that's why I thought of it in Moho).

Moho's particle system can be very useful because it interacts directly with Moho's animation but, yeah, it can also be limited compared to particle systems found in other programs. I like to use a third party plug-in for AE called Trapcode Particular; it's way more capable but it's also very expensive. That said, Trapcode Particular is probably overkill for many things you might typically want to do in Moho, so it's wise become familiar with the strengths and limitations of Moho's system before turning external systems.

In short: know your tools.

[AnjaFrey]

In short: know your tools.

YES! I try ...

[AnjaFrey]

There are many ways to do this, but one 'easy' way is to create a straight line with many points (you can do this manually or just use Hayasidist's handy shape creation tool,) and then apply [Scripts>Warp>Wave...] The only problem with this method is that it doesn't automatically make the animation cycle seamlessly so you may need to find a point where you can trim the animation to be close to cycling, and then tweak the points to smooth it out.

Thanks also for the idea to adapt the keyframes of the wave script and turn them into a cycle! By the way - your website + films + tutorials are really nice!

[Greenlaw]

By the way - your website + films + tutorials are really nice!

Oh thank you! I have a few more tutorial videos that I still need to post, but first there are issues with the website I have to fix. After the upcoming holidays, I hope to start posting new content regularly again.

[AnjaFrey]

Oh thank you! I have a few more tutorial videos that I still need to post, but first there are issues with the website I have to fix. After the upcoming holidays, I hope to start posting new content regularly again.
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I am looking forward to it - have nice holidays!

[SuperSGL]

Slowtiger's Idea looks good and if you have lots of points on the wavy lines you might be able to use the new script 'Noisy Point Animation'