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Functionality review for a specific project - Elend - 14-06-2020
Hello , I'm working on a hyper-casual simulation game for Android and IOS.
I'm reaching out to you about Obi assets on Unity Store to make sure that the assets can fulfill our specific needs for this simulation project.
In this project we need to simulate vacuum packing. in the vacuum step there must be a plastic sheet that covers different objects (fruits , clothes , ..) and physically and perfectly sit on them as a piece of cloth would. The only difference is that it will have a special shader to simulate a plastic sheet.
In the next step the player interacts with the plastic sheet and can start vacuuming or pause and resume it. in the process the plastic sheet gets tight around the objects (just like vacuuming in real life when the air gets removed from the plastic film package) so we need that specific plastic sheet to be able to simulate that effect and be intractable.
I put an image here just to make things clear
RE: Functionality review for a specific project - josemendez - 14-06-2020
(14-06-2020, 12:25 PM)Elend Wrote: Hello , I'm working on a hyper-casual simulation game for Android and IOS.
I'm reaching out to you about Obi assets on Unity Store to make sure that the assets can fulfill our specific needs for this simulation project.
In this project we need to simulate vacuum packing. in the vacuum step there must be a plastic sheet that covers different objects (fruits , clothes , ..) and physically and perfectly sit on them as a piece of cloth would. The only difference is that it will have a special shader to simulate a plastic sheet.
In the next step the player interacts with the plastic sheet and can start vacuuming or pause and resume it. in the process the plastic sheet gets tight around the objects (just like vacuuming in real life when the air gets removed from the plastic film package) so we need that specific plastic sheet to be able to simulate that effect and be intractable.
I put an image here just to make things clear
Hi,
You won't be able to simulate this with Obi, at least not easily:
- We don't simulate air dynamics inside a cloth piece. "Air" inside a watertight mesh is simulated as a single scalar quantity instead, so vacuum effects can't be simulated out of the box.
- It is a particle-based engine, so collision detection is performed using particles. You won't ever be able to get a perfectly tight fit of the wrapped plastic over its contents, there will always be a gap between them (its size = particle radius). Also, any contents of the plastic bag that are small relative to particle size will miss collisions, forcing you to choose between a large gap between the surface of the bag and the contents, or good collision detection.
kind regards,
RE: Functionality review for a specific project - Elend - 15-06-2020
(14-06-2020, 04:47 PM)josemendez Wrote: Hi,
You won't be able to simulate this with Obi, at least not easily:
- We don't simulate air dynamics inside a cloth piece. "Air" inside a watertight mesh is simulated as a single scalar quantity instead, so vacuum effects can't be simulated out of the box.
- It is a particle-based engine, so collision detection is performed using particles. You won't ever be able to get a perfectly tight fit of the wrapped plastic over its contents, there will always be a gap between them (its size = particle radius). Also, any contents of the plastic bag that are small relative to particle size will miss collisions, forcing you to choose between a large gap between the surface of the bag and the contents, or good collision detection.
kind regards,
Hello and big thanks for the explanation
I cant find any other solution for this simulation so I still insist on solving it with Obi Assets ,
specially that the vacuum effect has to be something like reducing that gap you mentioned , so is there anyway to do that in rune time game?
something like that pressure that is in documentation.
also can you please be kind and explain about Obi SoftBodies ? is it not possible to simulate the vacuum with that ?
its something like in this video :
https://www.youtube.com/watch?v=h7xVz-wsNEY
again thanks in advance !
RE: Functionality review for a specific project - josemendez - 15-06-2020
(15-06-2020, 01:04 PM)Elend Wrote: Hello and big thanks for the explanation
I cant find any other solution for this simulation so I still insist on solving it with Obi Assets ,
specially that the vacuum effect has to be something like reducing that gap you mentioned , so is there anyway to do that in rune time game?
The gap I mentioned can't be completely eliminated with a particle based engine, sadly. It's at the core of how particle collision detection works. Can only be reduced, by reducing particle size. But as I mentioned, this in turns makes collision detection less robust, so you would have to balance the two.
(15-06-2020, 01:04 PM)Elend Wrote: something like that pressure that is in documentation.
The pressure model we use is not spatially variable: it's a single scalar value that determines the amount of outward pressure applied to cloth faces. Note this is not intended to be an accurate pressure model: in the real world, pressure varies over the surface as a result of air fluid dynamics.
(15-06-2020, 01:04 PM)Elend Wrote: also can you please be kind and explain about Obi SoftBodies ? is it not possible to simulate the vacuum with that ?
No, it's not possible. Softbodies are simulated using shape matching constraints, which do not take into account air or pressure in any way. Here's a video of the technique we use:
https://www.youtube.com/watch?v=LRHqs4GJuCA
(15-06-2020, 01:04 PM)Elend Wrote: its something like in this video : https://www.youtube.com/watch?v=h7xVz-wsNEY
again thanks in advance !
That video shows Blender's cloth simulator, which does not run in realtime in a desktop computer, even less in a mobile device. This level of detail just can't be achieved in realtime.