Is it possible to recreate standard POPs as VOP POPs?

[magneto]

lol if that happens I will be at the front lines with you

[magneto]

Now that we have all POPs in DOPs, I just checked the help files to see what variables we have access to, and it seems like all of the POP variables are gone, which is to be expected since they are VOP/VEX/DOP based?

But how would we go about accessing AGE, LIFE, REST, JUSTHIT, DIST, etc?

Because before I thought it was a matter of choosing speed vs flexibility, but now since the new POPs are meant to replace the old ones, will there be new ways to do similar things?

[old school]

@age is $AGE

@life is not $LIFE at all but total lifetime of the particle

@nage is $LIFE or normalized age life from 0-1

vector rest if it's in the details view, can be inherited with:

v@rest

JUSTHIT can be gleaned from the POP Collision Detect DOP. It adds geometry attributes that can be inherited by <type@attrib_name>. Use the geometry spreadsheet in the Details View to see what attributes get added. All Point attributes can be inherited by type@name.

There are a few example files already for some of the POPs. They were created to help the transition. There should also be some VExpression presets in there soon to create typical expressions you may want to use. There will be more example files added as well.

Are there new ways to do similar things? You bet!

In old POPs you always had to fight with velocity directly as acceleration was not that effective. In new POPs, force is far better than accel was. I use force almost exclusively now. It just gives you such a nice organic feel when motivating particles about.

Directly mucking with velocity feels "dirty" to me now.

So using force in place of directly affecting v is one big change that I had to wrap around.

We definitely tried to make the transition as seamless as possible. For example, ignore mass is on by default on all POP modifier type DOPs. That makes using new POPs similar to old POPs in terms of behaviour.

But...

You can absolutely add a POP Property DOP, create the mass attribute for the particles, then disable the Ignore Mass toggles and have lots and lots of fun! Increasing or decreasing the mass now "feels" like you are changing the mass. Again we disabled mass as we wanted the transition to be as smooth as possible.

Then there is the sheer number of particles you can create that also changes things up.

[magneto]

Thanks alot old school, it really cleared things up. Now I understand how to use the new particles.

There is one thing I am confused about though. I remember reading recently about the new particles being automatically parallel because of DOPs. Is this true? I thought that would be possible if they were written in VEX/VOPs, but it seems like the new POPs are made using DOPs?

I will post where I read it if I can find it

[old school]

VEX is inherently parallelized so that is where that statement comes from.

Pretty much every new POP type DOP node is an asset that wraps on top of a SOP Solver and usually with some visualization data piped in and then on to an Enable Solver DOP and then merged in to the input. So almost everything is done inside SOPs. A lot of work went in to making the new POPs feel like old POPs. As well a lot of work went in to DOPs themselves to allow chained networks and the new workflows that POPs demanded.

The SOP Solver invariably contains a lot of VEX/VOP operators doing most of the heavy lifting.

Some other interesting things to note:

- Streams are actually created by Group SOPs in these SOP Solvers.

- There is a bit of magic happening to expose groups at the top level as streams. They show up looking like geometry attributes but they are Streams, not attributes, not groups at the top DOP level.

Dive in and have a look at some of the new POP type DOPs. Lots of interesting subtle things are going on in there that you can borrow for your own assets.

[magneto]

Thanks old school. It's amazing that all of the POPs are recreated in DOPs using VEX/VOPs, etc. Certainly pretty much everything in this thread come true

From what I noticed the old POP networks and all the older POPs are still visible in the TAB menu. Are they not supposed to be completely obsolete now? Would there be ever a case where someone might want to use them in H13? It seems like the new POPs do everything the old POPs did and then some more

[graham]

Everyone likes backwards compatibility.

[magneto]

Thanks yeah, I was just expecting them to be invisible but still available just like all the other obsolete stuff in Houdini. So they will load if the file uses them, but otherwise invisible

[yesyes]

the old particle SOP was also available in houdini 12(don't know about 13 yet), so they will be there

[magneto]

I thought the Particle SOP was there for people who don't have an FX license but still want to use particles.

[anim]

...

We definitely tried to make the transition as seamless as possible. For example, ignore mass is on by default on all POP modifier type DOPs. That makes using new POPs similar to old POPs in terms of behaviour.

But...

You can absolutely add a POP Property DOP, create the mass attribute for the particles, then disable the Ignore Mass toggles and have lots and lots of fun!

...

As far as I remember old POPs have Ignore Mass off by default and that is logical behaviour

since POPs have no mass attribute by default, all nodes behave as there is no mass difference (or as mass == 1 or as if Ignore Mass == 1) so the actual value of Ignore Mass doesn't matter

and when you add mass attribute it's immediately used as expected, no hunting for Ignore Mass switches (only if you want some node to ignore mass for some reason)

so how is this Ignore Mass on by default helping users with transition if it's not logical and actually opposite to old POPs?