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Feather

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Feather last won the day on October 17

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    Vlad
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  1. Hard constraints stretching beyond rest length?

    This method seems to be far more controllable. Thanks again Pavel!
  2. alembic objects into copy to points

    Have you tried using alembic archive?
  3. Hard constraints stretching beyond rest length?

    Thanks Pavel, I've been able to get it to remove prims based on exceeding a certain force limit as you suggested. They do not stretch in this case much at all but It does seem to apply forces evenly across the entire object. Once it reaches the threshold all of the constraints break at the same time. I'm sure I could set variable thresholds for the break to occur where I want it to but without anything impacting the object I would be basically painting certain weak points so I doubt it would produce a very natural result. The object I'm breaking is made of long beam structures that pull and rotate each other as they fall. I want to make sure that as they are getting torqued I can split and splinter those beams naturally under their own weight. Without an impact, determining where torsion would occur would take a bunch of simulations and repainting. Is there a more natural way to find stress points between pieces and weaken them dynamically?
  4. solver not working on animated mesh

    Sorry if I was unclear. Plugging your wrangle into the Object_Merge is not all of what I was suggesting. You you cannot simply switch the input of your wrangle. Important information is coming from each of those nodes. (Object_Merge)Input_1 is the geometry being fed into input 1 of your solver. It updates each frame and pulls in whatever is plugged into input 1 into your solver. Meaning this is your animated geometry. From this object merge you need to take the point position and use that to update the position of the points you're solving the infection on which is Previous_frame.
  5. Hard constraints stretching beyond rest length?

    Thanks for taking a look and no worries on the experience thing this is like.. exactly what the forums are for, I don't know either haha I guess it very well may be an unsolvable thing like unstoppable force vs immovable object. BUT this is a pretty common situation in destruction where you have a base simulation and want to do secondary fractures. For what its worth I've just tried glue constraints with different strengths. For example the would be hard constraints are -1 and the middle is set to some random strength. THESE STRETCH TOO. They don't snap back to their rest length like the hard constraints though.
  6. Hard constraints stretching beyond rest length?

    Continuing this in hopes someone can help me out. I had a suspicion that the hard overwrite of the "Animated Static Object" may no play nicely with the constraints and so I tried using a constant force to see what happens. Turns out even with a constant force of like 10^10 you get ... this. It does seem to respect the hard constraints more but not really all that spectacular a failure. >.<
  7. Hard constraints stretching beyond rest length?

    Still trying to find a viable balance between the glue and hard constraints but they simply don't behave as I'd expect. Sti I would expect that hard constraints are respected explicitly and do not break or stretch. I would also expect that glue constraints not matter how strong, when a piece with a hard constraint is under force would always break. This seems to not be the case, different levels of glue strength and RBD object density result in long and shorter stretch lengths before the glue decideds to snap in a catastrophic failure sort of way. From what I've gathered, A glue strength of 1 per 1000 units of density is the balance point for glue that will stretch the hard constraint only a slight bit but I can't seem to drive this otherwise and it's not very intuitive. Attached is a more simply animation example to really make this obvious.Snap_Constraints_Example_2.hip snap.mp4
  8. solver not working on animated mesh

    First of all, if you can help it, use Alembics. Will save you a lot of headache. Second, you're running your simulation using previous frame as the input to your wrangle. If the previous frame was the first frame of anim... that's what your solvers going to use every frame because its never looking at the new anim. You need to use the object merge Input_1 to update the position of all your points to match the new position of your animated FBX. Previous frame is where you can pull the last frames infection data from and apply it to the points of the new anim frame before solving the next frame.
  9. When you convert multiple primitives to a VDB the VDB is a single primitive, hence you're only getting one name in the process. You need to do this conversion inside a for loop(by name) to ensure the correct name is copied to each piece.
  10. I can't figure out why the hard constraints are stretching before the glue constraints break. The hard constraints have a rest length and as far as I'm aware its not being updated. I've set the constraint iterations to 30. 60. and even 100 which does help but they continue to stretch. Upping this iteration number isn't viable in terms of time for the scale simulations I'm looking to use this and so I'm hoping someone can help me. Maybe I just shouldn't be using glue here at all? I've put together a quick and dirty example file of this problem and attached it below. Snap_Constraints_Example.hip
  11. FLIP SIM- Collision and Sticking Problem

    I just ran into this last week actually. Using a volume sample and pointing to a collision volume with a division size below .01 resulted in this box like error. It seems to only happen if the collision volume drops to a division size of less than 0.01 but otherwise is fine. I couldn't seem to get this to show up in the collison display or trouble shoot it. If anyone can help I would appreciate this as well.
  12. Bullet Collision problem

    Hey all, I'm trying to pack primitives for the bullet solver that include baked ODE data for compound collisions proxies. The red nodes are a method that is currently not working but is ideal for setting up constraints. Attached below is a example file with identical inputs to identical simulations with one key difference. In green I am baking ODE data inside of a for loop and packing each object individually the ODE data is maintained and the simulation works. In red I am copying the name data to the ODE baked primitives, and instead pack each piece using the name attribute OUTSIDE The forloop. In this case the ODE data is lost. There are two nulls on the side where I've broken out a single identical piece to show the ODE data difference for each means of processing the pieces.Does anyone know why the pack using name would remove the ODE data from the piece? WhyTho.hip
  13. Flip solver problem

    Is this what you're after? There were a couple things here regarding the collision and the way you had set up the solver. Don't want to explain in detail if I misunderstand the question. Coffee.mp4 Before I attached the Hip file it needs notes, pending your response, don't wanna do a bunch of notes if Im misunderstanding.
  14. Wind from rotating fan

    Theres an additional input atop the solver for a external velocity force. I mean you could try running both simulations simultaneously and having them interact but.. if you're not really looking for anything visible from the van velocity then I Would just cache the directional velocity of the fan sim and use it as a force in the following smoke simulation and rbd sims.
  15. Smoke - flat leading edge

    Without seeing your hip file I can only take a guess. That plateau looks like you've multiplied up the density of what would have otherwise been a very thin or empty voxel. If this is the case you're sending density values greater than 1 into your shader which is often going to make your shading experience a bad one. The image below from left to right is. 1. The original simulation, with a density of 1 and a shader render density of 1. This is the sim's natural look. 2. This has a post multiplication of 10 before and a shader render density of 1. This is what I believe you've done and why you see the plateau. 3. This is the same volume, with a density of 1 and a shader render density of 50. This is the correct way to make a thin simulation render more dense without lifting the empty voxels. Either you need to lift the density emitted in your sim to begin with or make sure that you're working with the shader to change the look of the sim, not the actual density values Edit: This sim has an upward velocity of about 20-30. The leading edge is curved but when rendered incorrectly will look flat because the curve is very subtle. Cranking the density values before it gets to the shader erases the variance responsible for the curve. .
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