Kinematic Collision not working 100%

Support ForumCategory: IssuesKinematic Collision not working 100%
James McCavana asked 3 years ago

Hello, I really need your help. Great product by the way.
I have created a static particle field, and have a sphere moving through the particle field which is meant to push the particles aside. However, there is a large number of the particles that simply go through the sphere and are not affected by the physics of the collision. I need 100% collision detection and any particles in the path of the sphere to be pushed out of the way.
The effect is nearly there, so I believe I have the nodes/effects set up correctly, it’s just these sneaky particles that ruining everything.


7 Answers
admin Staff answered 3 years ago

Hi, there are several settings that affect the collision detection . Size and Speed, particles too small or too fast might get through
Setting the World scale to be larger, and having larger margin should give more stable result,
Simulation accuracy.
Please send us an email for further help.

James answered 2 years ago

This is not good enough. I’ve got to get this working, as I’m on the job now, doing particle effects. It seems to me that this should be at least the most basic requirement of a dynamic particle system, and to be honest, I’m disappointed.
I will reiterate the problem, I have a static particle field (emitter is a large box, X=800, Y=20, Z=800), with a little bit of turbulence and a subtle wind force so they move around a bit. I then have a model (transparent primitive sphere) simply moving through the particle field, pushing all the particles out of the way, to clear a path. This effect is comped onto a camera-tracked shot of a cyclist on a busy road. The cyclist is where the transparent sphere is, so the cyclist is pushing the particles (pollution, dust, smoke) out of the way.
I’ve tweaked world scale and margin, but i’m not getting the results I need.
When I look at all the complicated tutorials of crazy stuff Stardust seems to be able to do, I’m amazed that it doesn’t do something so ridiculously simple as this. Please help me, I’ve got to show them results, and i’m very close to ditching Stardust and moving to X-Particles (which I really don’t want to do).

James answered 2 years ago

The only way I’ve got it working is to increase the size of the particles. The problem is, they now look like a field of tennis balls, when it’s meant to look like dust.

James answered 2 years ago

Even increasing the world scale to 1000 does nothing

James answered 2 years ago

I’ve looked into using the Field node, a spherical field, but that doesn’t push the particles away, it simply wraps them around the field sphere. Maybe it’s possible to adapt the Field node to do what i want? it seems more reliable than the Model/Physical method.

Nik answered 2 years ago

Hello James – I am running into the same problem here — did you get any answer from them

Andy Engelkemier answered 2 years ago

I’ve only just started here, but if it’s anything like other particle systems, and everything points to yes, then you just have to cheat. How you cheat is usually up to you, but one suggestion would be to increase the size until it works. But then make those particles invisible. Then have Those particle all emit 1 particle each, the size you actually want. 
The thing you have to realize, with any simulation, is there is a balance between accuracy and speed. If it’s 100% accurate all the time, it would be unusable. If they strip it down so much that it’s real-time all the time, then it becomes not useable also because you can’t get Anything to give you expected results. 
So get creative in your solutions. Another idea is make them the size of tennis balls, then move your camera back until it’s the size of dust. There is more than one way to skin a cat.

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