General workflow questions/ FAQ update

[insertmesh]

Can we make a sticky thread with general workflow questions? Or with Q&A that should be added to the FAQ section? I´m going through the manual, trying to reduce the quesions I have regarding specific problems, by sorting through the the general workflow issues I have...

Its a good Idea to start with the "FAQ" section of the manual, as it already coveres, you may have guessed, a lot of these frequently asked questions...:

http://docs.tyflow.com/faq/

Here are a couple of my questions:

1. Cascading simulations.

From the FAQ:

Use Birth Flow operators to chain multiple flows together, allowing for some flows to generate the initial state of the simulation (requiring only one computation of that state), while other flows (that are continually updated) work from that initial state.

What information of that initial flow gets carried over in the Birth flow?
For example:
1. I have a grain sim setup and want it to settle, before sending it to the next flow, where there is dynamic interaction with other elements.
2. I let the settle flow (A) run for 100 frames, then I pick it as a birth flow in the second flow (B).
3. I basically copy all the ops from flow A to flow B, including all the particle bind and particle physics ops.
4. I set the Birth flow in Flow B to use frame 100 as starting point.

Question:
Do I even need the particle bind and particle physix op in Flow B, or do those infos get carried over from flow A?
What if I had some dynamic interaction in Flow A, simulated til frame 100...would they continue to sim in flow B?

Answer:

In a Birth Flow operator it lists all the channels you can bring over 

Unfortunately particle bindings are not included. However, maybe in the future they will be. 

2. Physx and particle physix/particle bind combination

Question:
How do I combine Physx and particle bind/particle physx together in one flow? Is it possible to get a two way interaction between these two and if so how would I generally set this up?

Answer:

Right now because the PhysX and particle bind solvers are independent, there's no easy way to achieve 2-way interactions.

Update: You can however have rigid body to particle solver interaction, simply add your rigid body in another event and in the particle physics op untick "Process only this event" and "Affect only this event", see example below.

3. Turning of grain/cloth dynamics for an event

Question: 
From Pflow physx I´m used to using the Physx Switch to turn off particle dynamics in one event and turn it on in another.
How can I do this with particle Bind/particle physx? Say want to create  bunch of spheres floating around randomly, WITHOUT deforming, but once they collide with something or some other test is performed, they should behave like cloth.
Would I birth them in one event and in another event turn them to cloth via the cloth bind op?
Could I also turn them into grain or into rigid bodies in another event? And then turn them back again into normal particles in another event?
A bit of testing will certainly show whats possible, I´d just like to know some common mistakes one could make here or some general workflow advice...

Answer:

This is correct. You can also see the "Particle Switch" operator allows you to exclude certain particles from the bind solver. Also the Cloth Bind operator has a mode (listed at the top) for converting cloth back to particle shapes.

4. Avoiding unnecessary updates

Question:
I have noticed this specifically with grain sims: Whenever I change anything in a flow on frame 0, it immediately starts recalculating some stuff (i think its mostly the particle binds, even if I haven´t change them).
This can get a bit tiresome and I started just turning it off before changing multiple settings at once.
Is there a way to avoid this update on the first frame? 

Answer:

5. Using simulated flows as particles in another flow

Question:
We can use Birth Flow to pick an initial state of another flow.
But lets say I´ve animated some cloth stuff in one flow and want to spawn that animation as particles in another flow. Is that possible and if so, how do I do that?

Answer:

Yes, although only the channels listed in the Birth Flow will carry forward....bindings do not.

thats all I can think of right, now if someone knows the answer to any of these questions, I´ll update the thread, if you have more questions like this, I´ll also add them.

[tyFlow]

What information of that initial flow gets carried over in the Birth flow?

In a Birth Flow operator it lists all the channels you can bring over

Unfortunately particle bindings are not included. However, maybe in the future they will be.

How do I combine Physx and particle bind/particle physx together in one flow? I

Right now because the PhysX and particle bind solvers are independent, there's no easy way to achieve 2-way interactions.

Would I birth them in one event and in another event turn them to cloth via the cloth bind op?

This is correct. You can also see the "Particle Switch" operator allows you to exclude certain particles from the bind solver. Also the Cloth Bind operator has a mode (listed at the top) for converting cloth back to particle shapes.

4. Avoiding unnecessary updates

Better reset behavior is on the todo list for exactly the reason you mention. Currently the plan is to change it so that it will accept tweaks but just keep simming forward, rather than accepting a tweak and restarting.

We can use Birth Flow to pick an initial state of another flow.

Yes, although only the channels listed in the Birth Flow will carry forward....bindings do not.

[insertmesh]

Right now because the PhysX and particle bind solvers are independent, there's no easy way to achieve 2-way interactions.

Ok, gotcha. Question is of course...why would I need this. Just figured out a simple way to do that:

1. Create grain sim event.
2. In the same flow, create birth shape event.
3. in the grain sims particle physics op uncheck "process only this event".
4. Boom. Two way interaction with grain and rigid body...

https://media.giphy.com/media/LkYhPTd8PI.../giphy.gif

[Jokermax]

that looks great, should be included as example file

[insertmesh]

Thanks... Yeah, it takes a while unlearning all the stupid workarounds from Pflow...

[tyFlow]

Nice result!!

[d4rk3lf]

Is there a way to bind part of the cloth particle to an object?
I want to make grass, blown by the wind. I want to use cloth for that, but I need to tell particle cloth to not move bottom parts of the grass.

I've tried ID, and test object... but so far... not too much success.

[tyFlow]

Send the particles you want to freeze off to an event with a Particle Switch in it, set to deactivate.

[insertmesh]

Ok, got another one...

6. How to have multiple Physx shapes react to each other?

Lets say I have a sphere set to collide and fracture with a box below it (using gravity). Once the sphere hits the box, the sphere fractures.
But lets say I now also want the box to fracture, when the sphere hits it.
Seems simple, but I´m missing something here...

Again, this could be easily done with two cascading flows, but can I also do this in one flow, so I have two way interaction between box and sphere fragments?