Help Per particle phase change

[ckyun777]

Hello

I'm working on welding simulation.
Is it possible to change per particle properties?
For example, viscosity of a particle can be changed by external heat? and getting colder as time flows?
Is it possible to make some particle become a sleep state and activated by external trigger so the computation load can be optimized.

Thanks!

[josemendez]

Hello

I'm working on welding simulation.
Is it possible to change per particle properties?
For example, viscosity of a particle can be changed by external heat? and getting colder as time flows?
Is it possible to make some particle become a sleep state and activated by external trigger so the computation load can be optimized.

Thanks!

Hi,

Not currently. Fluid properties (viscosity, rest density, etc) are specified per-material instead of per-particle, to save memory.

Also the viscosity required to transition from fluid to solid is extremely high, well outside of the stability range of any realtime simulation method, so this isn't a practical idea anyway (unless coupled with additional constraints such as shape matching, springs, etc...none of them currently available in ObiFluid).

[ckyun777]

Hi,

Not currently. Fluid properties (viscosity, rest density, etc) are specified per-material instead of per-particle, to save memory.

Also the viscosity required to transition from fluid to solid is extremely high, well outside of the stability range of any realtime simulation method, so this isn't a practical idea anyway (unless coupled with additional constraints such as shape matching, springs, etc...none of them currently available in ObiFluid).

Thank you for quick reply.
Is it possible to make each particle has its own properties, if I purchase source code? If so how much is the price?

Thanks

[josemendez]

Thank you for quick reply.
Is it possible to make each particle has its own properties, if I purchase source code? If so how much is the price?

Thanks

Hi,

The change is far from trivial if you're not experienced in low-level programming.

Our physics library is written in C++ and performs custom aligned memory allocation (we need it for SIMD), which means in order to pass data to/from Unity, you need to copy it over. Doing this for all particles every frame is very costly, so we restrict it to essential data only when needed. In order to allow efficient data sharing, we're working on abolishing copying, a must for per-particle fluid properties.

Memory mapped arrays will debut in Obi 4.0 (Unity 2018 and up only) bringing this performance overhead down to zero. Also, we are working on multiphase/multirresolution fully mixable fluids. This will enable not only per-particle viscosities, but per particle everything: rest densities, temperatures, etc.

We want to release it before the end of this year, keeping the current price of the asset.