Basic POP question *noob*

[hopbin9]

Hi,

Are there any tutorials out there on getting particles to form into different shapes. Like spheres, boxes or letters. I need to do something like that.

Thanks,

[Macha]

Try blendshape and attribute transfers (P).

Or run sim in reverse

Edited February 14, 2011 by Macha

[symek]

There used to be such tutorial in pdf, though it can be little outdated, it's here:

http://www.4shared.com/document/xPPzwy1e/pops_text4.html

There are a couple of ways for doing this, for example: let's say you know landing spot for every particle, because you've been cheating and you scattered points on a surface, one for every particle. Knowing this during a simulation (in VOP POP) for every point you find a position of its target. Subtracting both positions you get a vector pointing directly to particle target. Say, you scale it down, and use it as an acceleration lerped with a rest of simulation forces.

[Macha]

Symek-inspired solution (I like it):

force.hip

Edited February 15, 2011 by Macha

[hopbin9]

Yea, calculating a vector might be a good idea except that it will be hard to get them to go stop at the object or go towards the right point when other forces are applied.

@Macha - running it in reverse might be the approach I take . I was also thinking that might work.

[hopbin9]

Symek-inspired solution (I like it):

You're awesome!

Why did you use the Rest SOP, and not just create a new attribute?

[Macha]

The rest sop does it by default, so I deemed it easier for this purpose.

I attached another file where they stop when they reach the target, but you are right, it's hard to control, depending on what exactly you want, but it's an idea!

forcestop.hip

[hopbin9]

The rest sop does it by default, so I deemed it easier for this purpose.

I attached another file where they stop when they reach the target, but you are right, it's hard to control, depending on what exactly you want, but it's an idea!

Oh that is very cool.

What is the different between Point Velocity and Point Acceleration?

[Macha]

Acceleration is the rate of change of velocity. In pop context I think of it as another word for "force" (actually, force is acceleration times mass).

Often when I want a custom force I change this attribute. I have a feeling that the force pop and the drag pop are basically just accelerations.

Edited February 15, 2011 by Macha