View Full Version : finding the position of particles bounding box

08-14-2009, 11:30 PM
Is it possible to find out the centre position of the bounding box for a particle shape?

I have a swarm of particles moving all over the place using goals and i want to attach a volume axis field that will always sit in the "averaged" centre of the particles.

08-15-2009, 12:22 AM
Hey Chrispy,

This may help point you in the right direction.
So it has to be a runtime expression, because your particles are always moving.
Now to get the bounding box data you can run something like this:

float $bBox[] = `exactWorldBoundingBox particleShape1`;
vector $bBoxCenter = <<($bBox[0] + $bBox[3])/2, ($bBox[1] + $bBox[4])/2, ($bBox[2] + $bBox[5])/2>>;

particleShape1.theCenterX = $bBoxCenter.x;
particleShape1.theCenterY = $bBoxCenter.y;
particleShape1.theCenterZ = $bBoxCenter.z;

then create an expression on your field like this:

yourField.translateX = particleShape1.theCenterX;
yourField.translateY = particleShape1.theCenterY;
yourField.translateZ = particleShape1.theCenterZ;

Its fairly easy to set up from here, let us know how it goes.

good luck.


Actually I just remembered another way to get the center:

getAttr particle1.center;

Then follow the other steps described above.

08-15-2009, 01:06 AM
that's brilliant and works like a dream

thanks Ilan

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