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Everything posted by SquirkyTurtle

  1. Viscous fluid trail

    Hello Houdini people I am trying to simulate a very viscous sticky fluid wrapping around and hanging from a sphere but never fully dropping of it. The sphere moves around and I want the fluid to pull trails but be stuck to the object. I am kind of struggling with the approach and was wondering if anyone had any input of any kind? I have tried advecting particles by smoke and killing them off quickly to cause the Illusion of a trail but its not really what I want. I also played with surface tension and just normal trails but I feel its not going anywhere. I'm happy and really grateful about input of any kind
  2. Houdini flip "sinks" within boundary layer

    Does anyone have an idea why my flip sinks within the boundary layer like you can see below? It started at the same level as the boundary but when I cache it and play it back it starts "sinking" until it randomly stops at one point and reflects of the sides towards the centre? I am grateful for any help
  3. Flip simulation static object collision problems

    I changed the velocity from particle to volume and that fixed it. I am still not sure why this is but at least I am not getting exploding flip anymore
  4. I am having a massive problem with my flip sim and I have no idea what causes it. Basically, my simulation is a simple fluid tank, with some static static objects and one deforming static object, that I cached from another simulation. This object is a "thick plane" shattering and cracking, being pre-fractured and dynamically fractured using a "voronoifractureconfigureobject" in the other simulation and then cached as a .bgeo. I have made a collision volume for this using "collsionsource" and the collision mode is volume sample. I changed the collision separation on the flipobject so I get correct collision guides. Now, when playing the simulation the fluid displays unnatural behaviour. It randomly "explodes" all over the place. I added a sopsolver in which I manually tried to clamp the velocity and even set it to zero but it just causes points to appear in random places. I took some flipbooks and images, you can see them below. I have no idea what causes this and I am getting very desperate to fix it so I am super grateful for any suggestions of any kind. The second image is the collsison guide on the static object, the first one is the collision visualisation. I also attached a bit of tbroken_flip.mp4broken_flip.mp4he flipbook showing whats happening (one is with the velocity set to zero inside the sop solver, the other one is unchanged velocity). Also: I have tried using an rbd object, an rbd fracture object and a rbd packed object instead and I get similar results. I also tried higher seperation, remeshing the object before it enters the simulation, adding a trail to compute velocity and setting the objects velocity to zero on SOP level. I am also using a narrow band but I get the same results if I turn it offf. My scene scale broken_flip.mp4broken_flip2.mp4
  5. Dynamically add rigid bodies to flip sim

    I have kind of solved this problem and I am now just loading in all the objects from frame 1 and changing their active attribute as the simulation goes along. To do this I need a SOP solver inside my DOP but I am not sure how to wire the rigid body solver, the flip solver and the SOP solver together? I need the SOP solver to only affect the rigid body object. I tried using a multisolver but all combinations I tried seem to be not working and give me funky results with the flip. Does anyone know how to do that the right way? Edit: Never mind, I figured it out I think. I am using a multisolver for rigid body solver and sop solver and then I am merging that with the flip solver. I am not sure why this was not working previously, I might have had the wrong relationship in my merge node or something
  6. Dynamically add rigid bodies to flip sim

    Hello there I am working on a flip/ rigid body setup where I basically have some packed objects gradually being added to the simulation. They are simulated in another DOP and cached out and I need to drop them into the fluid DOP at one point (they leave one simulation and enter the other), which means the amount of rigid bodies in DOP 2 will have to update at simulation time (the first frame there is none, then they pop up one after another). I have a SOP solver and I thought I could just merge and update the geometry in there, which works when it comes to the rigid bodies, but somehow they loose interaction with the flip? Does anyone have any suggestions on how to do this the right way? Thank you!
  7. Crowd agent orient problem

    Thank you so much, that was a great explanation, I am really grateful! I got it now and my clips blend nicely
  8. Hello there I am doing a crowd sim and my agents need to turn around quickly after a certain event triggered and run away. Now I have a clip for the turn but when it plays the agents heading vector doesn't actually turn so when I try to do the transition to the running clip (and new direction) afterwards, the agents flip back and then turn around. I tried to solve this by manually updating the vector right when the clip changes but I get a horrible blend between the clips and stuttering in the movement. I am wondering if anyone knows a way to approach an issue like this smarter? I have set up a transition graph but I can only blend between both clips facing one direction and I am not sure if there is a way I can change the clip orientation? I am grateful for all suggestions!
  9. Crowd agent orient problem

    Okay, I made a quick example file with what I am attempting to do. Basically, I would like the turn clip to play and then I would like to blend into the running clip once the agent is turned. I am pretty new to this so I am sure I am not understanding or doing something right. example.zip
  10. Crowd agent orient problem

    Will do when I'm back at my computer, thank you
  11. Crowd agent orient problem

    Alright, so I have set the turning clip to be locomotion and the heading now updates but as soon as it switches back to the running clip, he starts turning backwards again? This clip is not a locomotion, should it be?
  12. Crowd agent orient problem

    Yeah I have but it isn't updating the heading, should it do that while the agents is spinning around? Do I have to do any setting up for this? Oh and thank you for your reply Edit: I did not set up the Locomotion right, I am stupid. On it now.
  13. Helllo there in my sim, I am using a voronoifractureconfigureobject and my simulation runs perfectly fine and my object fractures nicely until I add a static ground object. All over sudden there is parts that do not fracture anymore and I don't understand why. I assumed it might be that the fracture limit gets met once they don't eternally fall but if I put it up to a super high number, I get the same result. Does anyone have an idea what I am doing wrong? I am grateful about any kind of help. Thank you in advance!
  14. Ragdolls explode

    Hello! I totally forgot to reply to this but the problem fixed itself when I redid the collision layer so I assume something broke there. Thank you so much for your help though
  15. Ragdolls explode

    When my ragdoll state is triggered, my agents mesh explodes and breaks in the simulation in very disturbing ways. When setting up my collision layers and testing it outside of the dopnet, it seems to work fine. Does anyone have an idea why this is and what I have done wrong. I am using FBXs, but when testing with the Mocap characters from Houdini, it works fine. Thank you very much in advance.
  16. Ragdolls explode

    Nothing, it is not displaying any guide geometry. That is weird, is there anything I missed setting it up? I built the collision layer and then I configured the joints, is there anything else I got to do?
  17. Ragdolls explode

    Hey thank you so much for reply. Yeah that's what I did and its fine. I'm not doing a partial ragdoll but I am not sure what a motor driven ragdoll is? I'm just trying to trigger the state. I've also tried to just set the ragdoll state to active in the normal walkstate (the walk is fine) but it always breaks.
  18. Crowd and Rigid Bodies

    Thank you so much! I can't believe I missed this
  19. Crowd and Rigid Bodies

    Hi there! I am trying to make my crowd interact with some rigids (have them walk into a box and make the box move on impact ect.) but the box is not actually moving. I made a collision layer but when I try and display it in the solver, there is nothing. It works in the example sideFX file (ragdoll one) and as far as I see, there are no differences. I would be super grateful if someone could give me a nodge into the right direction Thank you
  20. How would I go about altering the velocity/speed or heading of my DOP agents manually? Are these attributes read only? Is there a way I can directly customise them using a wrangle instead of updating target points and attracting my agents to them? I would like to add some random steering to my guys and I would like to have more control over their speed and add variation but I am not sure how to approach this. If anyone could help me with this, I would be very grateful Sorry for the edit, but I have another problem: I noticed that when playing my simulation for 30+ frames, some of my agents start randomly disappearing. It shouldn't be the life expectancy as its really high and there is no variance. There is nothing in my simulation deleting them and I really can't tell any difference between the ones going and the ones not affected. It doesn't happen at once, its more like a gradual thing. Has anyone encountered that?
  21. I have two points and I am trying to figure out if there is a primitive "between" them (just if a straight line from A to B will intersect with it) but I am slightly stuck. I attempted this by calculating the distance between them and the distance along vector AB to the intersection and comparing the two values. But I can't seem to calculate the second. I have been using xyzdist() but I am not sure about how to approach the "along the vector" side of this as (as far as I understood it), xyzdist() just gives me the closest intersection without regarding a direction vector? Is there any function I could use for this? I would appreciate any help Thank you!
  22. Intersection with primitive along vector

    Okay, I figured it out. It was because for some calculations the point was past the point of the dir vector, so it just returned 0 because I assume it wasn't 'long' enough. I multiplied it by 10 and it works fine now
  23. Intersection with primitive along vector

    Yeah, I used intersect() and it works fine but, I assumed that &p: int intersect(<geometry>geometry, vector orig, vector dir, vector &p, float &u, float &v) would write out the point of intersection between the ray and geometry. For me, it just copies @P (orig vector) giving me the points position as the intersection point which clearly doesn't make sense. Did I understand it wrong? edit: I changed the orig vector to something else and &p gives me the orig vector every time? The dir vector is (goal - orig)
  24. Intersection with primitive along vector

    Oh wait, my brain just didn't function for a second there. I realised I could just use intersect() to get the point.. Sorry about this
  25. Intersection with primitive along vector

    Hello Thank you very much! That is cool but I need to figure out how to do this in VEX as well as I need it further down the line in my code. Would you know how to approach this?