I have some floating RBD pieces on FLIP fluid particles, and I would like to manually define the mass (density) attribute for each piece.
Is this possible?
Thanks for helping.
Different mass to each RBD fractured pieces, How?
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- Masoud
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- tamte
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you can use $OBJ local variable for example
so something like:
you can of course use it to pick $OBJ-th value from some SOP geo storing the piece density values on points using
or even from a space separated string using arg() whether its typed in manually or even stored as a detail attrib
etc...
so something like:
fit01( rand( $OBJ ), 500, 1000 )
point("../../OUT_piece_densities", $OBJ, "density", 0)
atof( arg("100 50 1000 75 1500 645.5 711 537.4", $OBJ) )
Tomas Slancik
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Hello Tamte
Thank you for replying.
Please take a look at my file. I tried this codes in the density field:
The spreadsheet indicates the density of each piece, which is useful, but the lower-density pieces always sink in the fluid!
Thank you for replying.
Please take a look at my file. I tried this codes in the density field:
point("/obj/box1/SRC", $OBJ, "density", 0)The spreadsheet indicates the density of each piece, which is useful, but the lower-density pieces always sink in the fluid!
Edited by Masoud - Feb. 9, 2025 03:29:25
Masoud Saadatmand (MSDVFX)
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- cncverkstad
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cncverkstad
can you use in your Project PackedRBD.
Is this image a Packed-RBD?
I tried to use Fractured-RBDs because I need to have direct control over each fractured piece, like applying different forces or tweaking specific interactions, fractured RBDs allow me to manipulate each piece independently.
In the image you uploaded, both of boxes are sinking, why?
Edited by Masoud - Feb. 9, 2025 05:49:20
Masoud Saadatmand (MSDVFX)
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Hi cncverkstad
In your HIP file, you used RBD with whole objects as a single piece. To separate them, I switched it to Bullet, but the simulation is very unstable now and always sink..!
And I don't know what are they white collision proxies in the middle of each geometry!
According to my researches:
- Packed RBDs are more efficient and are the go-to solution when you're dealing with large numbers of objects or large-scale destruction and want to optimize performance.
- Fractured RBDs are more suitable when you need individual control over each fractured piece or if the number of fractured objects is relatively small and you need to manage them individually for specific behaviors.
In your HIP file, you used RBD with whole objects as a single piece. To separate them, I switched it to Bullet, but the simulation is very unstable now and always sink..!
And I don't know what are they white collision proxies in the middle of each geometry!
According to my researches:
- Packed RBDs are more efficient and are the go-to solution when you're dealing with large numbers of objects or large-scale destruction and want to optimize performance.
- Fractured RBDs are more suitable when you need individual control over each fractured piece or if the number of fractured objects is relatively small and you need to manage them individually for specific behaviors.
Edited by Masoud - Feb. 9, 2025 06:17:58
Masoud Saadatmand (MSDVFX)
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- tamte
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MasoudThis is not correct
- Fractured RBDs are more suitable when you need individual control over each fractured piece or if the number of fractured objects is relatively small and you need to manage them individually for specific behaviors.
packed RBD is much easier to manage since you have control over every RBD's properties as points of packed prims
However the main reason people use Old RBD solver for mutual interaction with FLIP is that it correctly uses feedback data and its stable, for some reason the Bullet implementation hasn't been working with feedback from other solvers like FLIP so that would be the only reason to not use it in your case
Edited by tamte - Feb. 9, 2025 11:14:38
Tomas Slancik
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- tamte
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Masoudyou are not sampling density from the correct points
Hello Tamte
Thank you for replying.
Please take a look at my file. I tried this codes in the density field:point("/obj/box1/SRC", $OBJ, "density", 0)
The spreadsheet indicates the density of each piece, which is useful, but the lower-density pieces always sink in the fluid!Image Not FoundImage Not Found
the geometry you are pointing to has 16 points so both of your objects will sample density of 1000 which you can see in the Geometry Spreadsheet
so you either create geo with just 2 points and set density accordingly or just check Create Packed Primitives on your assemble
which will pack your objects but still promote our density attribute, that way
Fractured RBD will still be able to use correct geo based on name and the point() expression will correctly sample point based on $OBJ variable as there are exactly the same amount of points
EDIT: just to explain further as it may seem confusing
feeding Packed geometry to RBD Fractured Object DOP doesn't mean you get Packed RBD, just that the geo fed thee was packed, and RBD Fractured Object will still use it to create individual DOP objects for old RBD solver, packing in SOPs just helps representing each object as a single point and therefore allows having attributes that can be then sampled using point() expression based on $OBJ variable
Edited by tamte - Feb. 9, 2025 11:30:54
Tomas Slancik
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Framestore, NY
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