Instanced Particle Issues

[Xin13]

Hello everyone, I’m currently working on a project and I needed to have instanced cans rotated randomly and luckily I found this helpful thread http://forums.cgsociety.org/showthread.php?f=86&t=668834 to solve that problem.

Unfortunately another problem arose after that, in the cans seem to collide around a central point. This image is what’s been happening.

The particle expression is the same as the expression posted by lazzhar on the above thread link. I’m considerably new to using expressions and I’m stumped on how to solve this, any help is appreciated

[Xin13]

Any kind of suggestions or help is appreciated

[hkspowers]

The problem is you are adding rotations every frame in all axis. You need to pick a direction like so.

Creation: nparticle1.RotPP = <<rand(360),rand(360),rand(360)>>;
Runtime: nparticle1.RotPP += <<0,3,0>>;

If you want to randomly pick an axis to rotate around you would need to assign a variable that gives each particle a random number between 0 and 2 and write in your runtime expression an if statement that will assign a different axis of rotation based off that attribute.

Example Rotations

The expressions that were in that other thread will give you randomly rotating instances but they will all be rotating around the same axis. I have setup a scene that will randomly choose between axis to rotate about, and then apply the random rotations to those axis as well. The same technique could be used to vary the rate of rotation if you wanted to add the extra level.

As far as the collision goes, why are they perfectly spherical? Is there a collision sphere there? Or are you emitting from a sphere and cans are being instanced to it?

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