# Creating a particle array that dynamically fills a control volume

#1

I have an effect that I’m trying to achieve. I’m not sure if Max has the tools to do what I’m after, as I’m not as familiar with its physics or particle systems so I’m hoping that someone can advise me. This may well be a super obvious task that I’m butchering in my explanation so thanks in advance for your patience!

Image a static 3D array of particles, each set to a scale of 0, with an object moving through them all (E.g. a sphere). As this ‘control’ object passes over each particle, I’d like them to grow to a larger size, but not larger than the confines of the control object, filling it as best they can. As the object moves away from a particular particle it would shrink and disappear. Essentially, if we hid the control object, this would create the effect of the shape moving by ‘creating’ particles at its’ leading edge and shrinking them behind them.

I can create an array of particles that fills an object, and then just move that whole group, but that’s not quite what I’m after. I more want them to stay in place and grow/shrink in response to another object.

Here’s a super basic handmade example of what I’m talking about. In this example the particles are cubes and the control object is a sphere:

And here’s a super rough 2D version of the same principle which might be clearer?:

Hopefully I’ve explained this in such a way that it makes sense.

Would anybody have any suggestions as to if Max would have the tools to handle this? I’ve attempted to fake the effect in some 2D applications, but a 3D solution is increasingly looking better, and Max is my go-to here. If there’s another program that may do this better then I’d love to hear that, too.

#2

easily done in 2D

http://www.scriptspot.com/3ds-max/mcg/mcg-ibreakayouface

can also be done in 3D (ie. an element is a cube)…but it’s slooooow…

#3

Vol. Select and Push modifier?

#4

Volume Select turned out to be exactly what I was after! Push was a little problematic, but I found a few people doing tutorials for this exact effect with Morpher instead. Thank you!

#5

Push and Vol. Select with soft sel.
Yo can see parameters on pic.

#6

Thanks for that! Yes, Push works great for the basic cube array I described. When I said it was problematic I was more referring to it with regards to the ‘particles’ that I’m using in my actual end-result effect, which are made up not of cubes but a variety of shapes that don’t all respond as neatly to Push.

I didn’t describe those specifics initially as I was just trying to zero in on a general principle. Thank you for illustrating it in action, though. It’s a great help and will be helpful if anyone else finds this thread in future, too!

#7