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Everything posted by ejr32123

  1. While you are exporting I believe it is saving temporary files to a location (which I didn't have permission to write to). It tells you where in error. I used the chown command to give permission to write data there.
  2. Hello friends, I am trying to export from a mplay using ffmpeg. However, I keep getting this error (shown in photo). Any idea how to fix this? I am using Ubuntu 18.04 Thanks, ER
  3. VDB From Primitive

    If you want to use actual geometry have you tried using polygons but on the copy node turning on pack and instance.
  4. Hello! I was going to ask how to do this but I figured it out and so I might as well post this in case someone else has the same problem. If you want to source expansion for pyro in houdini 17, we don't have the fluid source node. Instead we have the pyro source. However, there is no expansion option for initialize. I remembered there was a shelf tool that auto-creates the nodes, so I tried it out. As it turns out (and seems confusing to me) you have to use the flip source then choose expand. Back in Dops you can use the volume source node and set it to expand also. Anyway, hope this helps-
  5. Hello! I have a dopnet in a subnet. Let's say I have a parameter from one of the dop nodes exposed on the subnet. If I want to use $SF in my expression it obviously won't work because it's trying to evaluate that expression on the subnet. Whats a good work around? I tried many other options like ch, chs, and chsraw, but nothing seems to work. Same problem if I want to use `opintputpath("..",0)` but have the control on the subnet. I want it to be the input 1 of the dopnet, of course. Thanks! subnet.hip
  6. HDA interactive button.

    ill take a look at that, thanks
  7. Hello! You know how shelf tools allow you to interact with the viewport? I want to do something similar like that for an HDA. I want when a button is clicked, cross hairs show up that allow the user to place points that will snap to the input geometry. What are some good resources that show how to do something like that? Thanks, ER
  8. Swirl Pyro Equivalent

    Hey, I have been struggling to get a nice swirling motion in slower moving pyro smoke simulations. In Maya fluids I had an option called swirl witch worked beautifully. I found an old post addressing this issue, but it seems to have died before arriving at a good solution: http://forums.odforce.net/topic/23132-smoke-swirl-vorticity-with-smoke-solver/ Here is a simulation I did in Maya using the swirl attribute. https://youtu.be/Ifd6FJ2oHIc In houdini I have been using disturbance but I don't seem to get the results I want. Disturbance doesn't really seem to add swirl but more turbulent detail. For example, look at this sim I found on vimeo. You can see the disturbance start overpower the simulation towards the end, it doesn't really add a swirling motion. https://vimeo.com/220668349 What is a good Idea to get nice swirls? Thanks
  9. Pyro Disturbance for high vel

    Yea, you'll want to use frame delay on the gas resize fluid dynamic node until the main part of sim starts (or until you already have good enough motion in the sim). Either that or disable it completely and just make sure your container is big enough for the whole sim. I think most of the time I only really need this for the first 10 frames or so then I switch to auto-resize.
  10. Pyro Disturbance for high vel

    Their are many ways to do it. I included two very simple ways to do it, just using some micro-solvers. I just have that running a few frames before sourcing my main sim. break.hip
  11. Hey, This is how I control the focus distance in Maya. I use a measure distance node, then use that distance to drive the focal distance so where ever I move the null, the scene is in focus. Can I do this in Houdini? Is there a measure distance node that can get the distance between two null objects? One null would be at camera's position and the other null where I want to focus. Thanks
  12. snap viewport image

    I do it all the time! https://www.sidefx.com/docs/houdini/basics/memorytoolbar.html You can even save your camera angle too.
  13. I think you should add your pscale before the particle sim. That way they will collide with the ground plane and not sink through. I added a pop grain node too. That way the particles will collide with each other. particle_mass.hip
  14. Sweep multiple curves?

    I am not sure exactly what you are talking about. Could you post a picture/hip of what you want. I included a hip of what I think you are trying to do. sweepy.hip
  15. VOPs - output to @P.y.

    what about something like this? Use get vector component and use component 2 which is Y. You can make as many changes to Y as you want then merge it back. Any changes here would only affect the Y position.
  16. Pyro / Volume Kill

    Have you looked at gas enforce boundary? I tried messing around with it before to delete density in certain areas.
  17. what exactly is the problem?
  18. changing the pscale doesn't seem to do anything on its own. Just create a mass attribute based on the pscale and apply a pop drag. Make sure to turn off "ignore mass". particle_mass.hip
  19. scaling pyro sims

    Generally, I just scale down everything to a size that I know gives me the best results. Then I play with the timescale to get the correct motion. It seems like having a smoke container too small yields longer sim times. Also having the smoke sim too big seems to run out of gpu memory faster and I get opencl errors. For very small scale liquids, collisions never seem to work well so I have to scale everything up. Even if you have everything physically correct you would still need to tweak settings to match your reference. Hope this helps--
  20. How do pyro collisions work?

    Hello, Could anyone explain exactly how pyro collisions work? In some cases, it doesn't seem like collisions with the smoke solver are "real" when using moving colliders. It seems like 2 things happen when using an animated static object: 1. Takes the velocity from the collider and advects the smoke with it 2. Delete any density that goes inside collision object (can be disabled) Look at my gif. If I disable velocity from the collision nothings happens. The density just gets deleted. In the example I turned off correct collisions for better visualization. If the collisions were "real", I would expect the density to move when the collider moves, then stop once the collider stops since no velocity from the collider is being applied. Any ideas? smoke_collision_test.hip
  21. How do pyro collisions work?

    @ikoon Thanks for the detailed answer- very helpful
  22. How do pyro collisions work?

    There really isn't a "problem" it is more so trying to understand how collisions work. I am not trying to achieve a look or do some effect. I am just wondering how collisions work. Just trying to see if what I think is correct about collisions: 1. Takes the velocity from the collider and advects the smoke with it 2. Delete any density that goes inside collision object
  23. How do pyro collisions work?

    It did talk about collisions for a paragraph or two, but its not clear to me. It does seem to indicate what I am thinking is true.
  24. Particles shrink as camera gets near?

    Here is a way of doing what atom said using point vop! hope this helps... particles.hip
  25. I finally got it working, I had to set permissions to /opt with chown. I am a linux noob : )