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Everything posted by 90okm

  1. Hi ! i'm trying to get volume data from points attribute pls see the attached picture in this case i set an attribute to some value and want it to be sambled into new VDB volume. it works like surface "wrapped" around my points (red area). and it's empty inside, although there are points inside with the attribute set to positive non-zero value btw it works fine when i set vdbfromparticles SOP to Fog VDB - it fills all volume where points exist Is it possible to sample any arbitary attribute into VDB like Fog VDB option does?
  2. Unfortunately NO! the default parameters produce the same effect as you can see the inner area is empty although i have points there
  3. FLIP Velocity leap

    HI ! i've faced the strange flip behaviour i have a flip container following some object and i create some disturbance area by transferring v attribute from points to flip particles. Nothing more - no collision , no additional forces... particle reseeding - OFF everything goes fine for a while, but at some frame the velocity field makes strange boost across all container , as you can see in the attached GIF what happens there ?
  4. Hi ! sometimes i create effects of ships going though ocean. and it's always a problem for me to get nice water-cutting effect that occurs along the ship front. I get more or less suitable result but i can not say that i'm satisfied with overall look.... the most obvious thing for me in this case is to add some custom velocities to the flip particles near ship's surface. I just get ship's normals and modify them a bit (see the attached picture), and transfer them as a velocity to flip particles using SOP solver This works, but it still looks unnatural... hmmm... Maybe some of you may share their ideas how to set up simulation that could bring nice water breaking effect. Thanks in advance !
  5. Hi ! i'm trying to get a better understanding regarding DOP data in houdini ! i can not find any detailed info the only way for me is just digging it myself. Starting from a simple experiment. lets say i have an RBD object and try to attach some data to it. as far as i know the solver looks for the specific data and change object's state according to that data. for example RBD solver looks for the Forces subdata and change objects position. if i create gravity force - Forces/Gravity subdata is created on specific objject and this object falls down to the ground. It works even if i rename Forces/Gravity to something Like Forces/Blablabla Well! Assuming this, instead of creating gravity force, i create an empty data named like Forces/Down and set "force" option to [0,-1000,0] with "modify data" operator. then with "apply data" operator i attach this data to object. (It's seen in Geometry spreadsheet tab) But when i press play button - nothing happens. Where did i make mistake ? or someone could point me to somewhere where i could find an extra info about DOP's inner matters? Houdini help is not much clear from this point of view Just in case i attach hip file. here Thanks in advance ! mydata.hip
  6. Hi ! trying to work with vex snippets and faced the problem ! I've created an integer array attribute on primitives and want to fill it with some values in attrib wrangle but i always get the error message of "Ambiguous call to array index operator ''. Candidates are: 'float vector4[int]', 'float vector2[int]', 'float vector[int]'" being declared within wrangle node the construction like this i[]@arr = {}; @arr[0]=@primnum-21; works fine wrangle_error.hip
  7. Yes it works, but it looks like declaring new attribute....that's why i was confused. thanks
  8. Hi ! I've just started creating effect of falling barrel. As the barrel falls all of its containment is being spilled out. The problem is that i can not use thicker walls in barrel because the liquid must flood area under fallen barrel. So i have to set up a thin-walled container, but in this case i faced the problem with flip leaking through barrel walls. Another one issue is the number of flip particles. a lot of them just dissapear ! The quantity of flip particles at the end of sim is much lesser than at the beginning (reseeding is on) How to cope with this issues ? I've tried to raise substeping parameter / collision resolution ... but still can not get appropriate results Pleas take a look at the attached file ! in this case you may notice particles penetrating the barrel around frame 35 Maybe some of you can suggest a hint how to prevent particles penetration/loosing? or the only thing i have at my disposal is raising substep parameter to some incredible values ? Thanks in advance ! b1.hip
  9. thin-walled container in flip simulation

    Great ! Thank You for precious advices it works well !
  10. thin-walled container in flip simulation

    Yes ! This is the very first thing i check before starting any simulation ! and collision surface seems to be ok ! I have even raised the resolution more than enough ! actually .... as far as i've noticed this is the common problem when you lose flip fluid volume , nevermind if you even have the constant quantity of particles itself
  11. thin-walled container in flip simulation

    Thank you for quick response....but the problem is still on. 1) The situation is getting better but there is a lot things to fix particles still go through container walls 2) I've measured the volume of particle fluid at the beginning and at the end of sim.... according to geometry spreadsheet - the volume of fluid at frame 35 three times lesser than at the first frame. the two-thirds part of fluid just goes away.... and it's not leaking... it seems like the solver just removes some particles out of simulation.
  12. Ship bow breaking wave

    Hi ! What approach do you use to get nice looking waves/splashes beside ship's bow ? it seem that simulating a ship as static object in fliptank does not produce that effect as its seen on different kind of reference. for the first i've tried to add some custom velocity around ship's bow that pushes the water out of the ship//but i'm not shure if its a good idea i've seen a tutorial regarding this matter but i can not find it so maybe some of you would share ideas how to get nice water-breaking effect
  13. Hi ! it seems that results of distributed flip simulation differs greatly from the same non-distributed simulation. the quantity of points and surface look differ greatly is there a way to achieve exactly similar results when i distribute flip simulation on several computers as it has in case when i simulate without distributuion? thank you
  14. Hi! if i run distributed simulation it seems that hqueue starts tracker on random computer from assigned list is there a way to force starting tracker constantly on specific machine and just put in hqsimulation an adress and a port for that tracker ?
  15. Hi ! i'm trying to learn the very basics of fluid simulation. and building network of microsolvers please take a look to attached scene. there is an empty object with two fields attached - density and velocity velocity field has a constant +x direction density is advected by velocity field. but while density is moving from voxel to voxel it loses data and blures. why does it happen ? is it connected to divergency or it's just an disadvantage of Euler method ? could someone explain me how to set up this simple simulation so that the density would remain constant and not blurred Thanks in advance ! advecting.hip
  16. Hi! What is the difference between solver inputs (pre-solve, velupdate, advection, post-solve)? as for instance i may plug my gasfieldvop1 microsolver in any pyro solver inputs. the simulation looks the same in any case. may be for this particular microsolver it does not matter , but for another microsolver it will do ? solver.hipnc
  17. scattered wires ! please help

    Hi ! I'm trying to simulate wires scattered on surface. there is a simple dopnetwork in the attached file. Whatever wire parameters i set these wires do not want to deform according to default gravity force. it reacts on gravity only when i set very large amount of force. I think that it's not a good idea to override gravity with some unnatural value, but i can not find correct physical parameters for wires in order to force them to act correctly with normal gravity value any kind of help will be appreciated/ wires.hip
  18. Hi ! i'm setting up a renderfarm under linux. I already have a license server in my network But i can not start hkey in GUI mode. I know that there is sesictrl command that helps managing licenses without GUI, but i can not find any extended info how to utilize it. i just need to change license server name could you suggest a command line for such operation ?
  19. Hi please take a look at attached scene There is a volume with two fields - density and mask I'm trying to displace central part of volume (masked with field "mask") But in render it looks like displaced part just "eaten out" or dissapeared. am i doing this in wrong way ? Thanks in advance. voldisp.hip
  20. Hi ! it seems like yet another topic about displacement artifacts, but i still can not find solution here is the object. It is shaded with simple shader, which produces single SSS pass color only and noise displacement in this render raytrace shading is turned on as you can see it has awful artifacts (pointed with red arrows). wthatever i do i can not get rid of them Displacement bound is ok Z-importance does not affect right way here is render with raytrace shading turned off seems much worse than i tried to render as subdivision artifacts are still there though it changed its position when i disable displacement everything seems to be ok what shoud i do to eliminate this artifacts ? re-dicind does not help other manupulation on SOP level (fuse, facet) also has no effects.... i'm in impasse..... PS houdini biuld 12.1.33
  21. wow ! thank You so much ! i suspected that problem was in geometry, but didn't understand exactly in what thanks !!!!!!!!!!!!!1
  22. here is the scene houdini 12.1.33 sss_rtraced.hipnc
  23. I used displacement bound (look at my message again) i know that there is a huge amount of info concerning disp bound... I wouldn't bother this forum with such simple issue as the matter of fact disp bound does not affect artifacts which i described above