Cascade - How to have a particle oriented according to its velocity vector?


I try to create a bird cloud using particles and a mesh for the birds. In spite of many tries and tutorials I didn’t found how to orient the birds mesh in a natural way during their movement.
I would like the particles to always point towards their velocity direction and to rotate left or right according to the direction changes, as a plan does for example.

Someone has some tips to achieve that?

Thank you very much

Go to the required module and change alignment to velocity.

Well, I’m afraid I need some more details…

The only Alignment parameter I see is in Mesh Alignment, and the dropdownlist contains only 3 items: Face Camera With Roll, With Spin and With Locked Axis.
In the same module, the Mesh one, there is an Orientation rollout, but no distribution refers to the velocity.

I tweaked many things and I still don’t see…

I think you might be better off using a crowd simulation. But that’s my personal opinion.

That was the other option when I started my setup. The thing is I don’t know much more about crowd simulation in Unreal that in particles (well, in Cascade).

I am quite surprise the particle editor doesn’t offer a way (or at least an easy way) to make particles point to their velocity axis and tilt according to the curve of the trajectory.

Hi werwack. The property you are looking for is not in the “Mesh” module but in the “Required” module. The property is call Screen Alignment and is set to PSA Square by default. Change this to PSA Velocity to have the particles face towards their velocity direction.

A crowd simulation would be a terribly expensive idea for something as small as birds in your level, particles have much less overhead and are specifically designed to simulate things for level decoration, I have used them for birds before via a simple Flipbook animation. The Vehicle Game demo on Marketplace (free from Epic) also has a cool vertex-shader bird in it that’s part of a particle system. It’s a much more sensible way to go about it.

Learning the ins-and-outs of Cascade is a must IMO, it’s a very flexible tool if your good with material shaders and its next iteration (Niagra) should be even more so.

I have been playing with Particles all day long, learned a lot, and now have a firm grasp on how to create certain FX (thank you again TheJamsh :wink: ).

For a bird particle, download the “Landscape Demo” and have a look at how they set up their birds, animation is driven by a material, but the system overall should help you with this isse. :slight_smile:

@EMc he is talking about geometry.
@DotCam correct mostly, He just seems to try and make it with geometry as his initial post says no idea why. Usually we create a loopable animation and play it in PFX or we offload the work to the crowd system.

Hi everybody,
thank you very much for all your feedbacks.

I’ve been able to play with the velocity alignment now. I didn’t find the parameter easily because it is labeled Screen Alignment and the tooltip describe all the possible values as related to the camera. Well, in my mind the particle alignment on velocity was more related to the world somehow. As I said, I am new to UE.

It’s a step forward yet I couldn’t manage to get what I am looking for: I didn’t find a way to force the particle to keep a given axis up not another one to control a tilt angle according to the particle trajectory bends. Maybe this is not directly accessible? If not, I hope to see that in Niagara :wink:

What I try to get is a kind of “plane effect”, where the birds can be seen for quite a close range and we get the feeling that they really tilt to turn. Download the animated picture here as an illustration (I’ve never been able to upload the gif…).
The example in the Landscape map is great, especially regarding the birds animation, but it also works well because birds are quite far or not moving around. I would like to make my birds turn around the player and do some sort of slalom (or at least collision avoidance) not far from him.

Regarding the birds animation I’ve been advised to try the flipbook and it provides good results. There are probably some other very efficient way to do the wings animation with the vertices position, such as an animated level on a gradient map maybe.

Best regards,