How to draw the trails of particles?

Hi, all.
I want to show the movement of particles, so I need to draw the trails of particles, but it seems that the particle system in cesium has no such API.

I see there is an update callback in particle system, but I am not sure if it can help me to draw the trails, because I can not tell which particle I am updating.

Any suggestion?

1 Like

What kind of application are you trying to build?

I haven’t used it myself but I think the particle system was designed mostly to create visual effects rather than simulate specific behavior. It looks like particles are created as billboards:

So you should theoretically be able to reach in and get that list of particles, even though it’s not exposed by the public API.

Although, you might be able to use a SampledPositionProperty and a Path to draw a path for an individual (or for all?) particles, here’s an example:

Entities have unique id’s so that can help you identify/map individual particles in the update function:

I hope this helped! Feel free to follow up here. I don’t see a lot of people on the forum using the particle system so I’m curious what kind of application you’ve found for it.

Thanks for your help.

I use particle system to visualize the 3D force field physics effect, mainly for the wind field. The movement of the particles are used to represent the force field.

Now I have 3D wind field data for Asia continent. I am planning to put about 50000 particles, because the area is very large. With so many particles(billboards), I wonder whether cesium will take a long time to render them.

So I think the particle system is optimized for this kind of use case, but I don’t know of its specific benchmarks/it will vary depending on whether you’re testing on a desktop, or mobile device etc.

The good news is Cesium has definitely been used to simulate and visualize these sorts of wind fields before. Here’s one I found from a quick google search:

I can see that they’re using geometry/primitives in order to get the maximum performance. So I would try with particles, and if you’re experiencing a slow down, you might try using the primitives directly. This is a good guide on that:

Thanks for your detailed suggestion!
I will give it a try.

在 2019年1月3日星期四 UTC+8下午11:36:43,Omar Shehata写道:

Awesome! If you get any cool results it’d be cool to see a gif or a demo! I also found out we have a whole meterology section in our demos:

Which might be cool to add to.

Hi, Omar

After two month's work, I finally make a particle system with custom render.

It is not good looking but at least it works. I attached a screenshot of my rough demo. And I made a Github repo:

Last but not least, thank you Omar! You help me a lot:!topic/cesium-dev/vR7H4KJURJ8!topic/cesium-dev/7kCcITmGbEA!topic/cesium-dev/gpgLjYyNFKE

This is awesome! I’m glad you resolved all the issues and have it running, and thanks for posting your code. I imagine it wouldn’t be that hard at this point to add color over time like this wind map (, or it based on strength/speed? Then it will look absolutely beautiful!