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Everything posted by Atom

  1. Short and sweet OP centric lessons

    I have created another short tutorial on how to alter the FLIP solver for correct Bullet Time emulation. You can view it here:
  2. Thanks for the replies. I ended up just placing a Fan Force right before Gravity in the AutoDop network. I setup a short keyframed pulse on the Force Per Unit Area and changed it to Set Always. This introduces a little bit of turbulence to the default static FLIP tank.
  3. Thanks for the detailed explanation Pradeep. As soon as I changed to Set Always the FLIP system updated and both fluids now act like they are in one tank. Is there anyway to add a little noise just to the rigid flip tank fluid?
  4. AO pass

    I think you want to use an Additional Image plane. This should provide the separation that you are looking for. You can route various passes into additional planes within an .EXR file using this technique. It is part of the Mantra ROP node.
  5. Adding Custom Agent To Crowds?

    Thanks for posting the followup file Zoran. I am just now getting back to this task. I am still struggling with making these posted files do anything. For instance, the crowd source node does not have a Reload button on my R13 screen. Is there another way to bake this simulation so I can see some animation?
  6. Thanks for the reply and posting the HIP file. I setup a couple of switches to compare my setup with yours. They are close in final output but there are subtle differences. Your setup uses Erode -> Smooth -> Dilate. My setup initially had Dilate -> Smooth -> Erode. But I put a switch on my setup to try out Erode -> Smooth -> Dilate as well. Here are some test images. r13_FLIP_smooth_compare_1a.hipnc
  7. I think I am closing in on a possible solution. This image shows a network where standard particles are converted to fog. The fog is converted to a VDB and connected to the Optional VDB masking input of the VDB Smooth SDF node. Dilate and Erode are also in play as additional controls for shaping the final ConvertVDB to polygon. The VDB From Standard Particles uses the pscale variable by default so no more wiring or coding is needed, according to the help. I would still like a way to add a MINI/MAX or FIT function to the fog to make it more bright in the middle and perhaps a falloff towards the wispy droplets.
  8. Here is a screenshot of my setup trying to implement what is being discussed in this thread. I used the VDB From Particles node in Fog mode as the mask for the VDB Smooth SDF node. This does work but I would still like to know how to created the masks talked about and I still don't know how to leverage the pscale to scale the actual fog volume. Any help would be appreciated. Can someone post a picture of the network or a HIP file with the setup working? Thanks
  9. Python's multiprocessing

    Are you talking about launching several threads from a single python script? From my experience, Houdini has two types of python threads. The ones that run in the interface which appear to be locked. This means If you place your code in a button and click the button, you lock up the process until that button script completes. The other option is to run your code from the Python Source Editor window. This seems to be a non-locked thread. Thus you can launch a process and have it running in the background while still using the Houdini Application.
  10. On the BlenderArtist forum they have a drop down at the top of the edit post advanced page that simply inserts [sOLVED] in the title. But manually typing that in the title is fine as well.
  11. Adding Custom Agent To Crowds?

    Zoki, thanks for the file. I am just now learning about crowds and agents so I don't fully understand your instructions on how to use the file. Save, I have downloaded the file so it is saved in my Downloads folder. Set Project...? I don't know what this instruction means. Bake Agents. I have selected the agent_bake node and clicked on Render Control and then Render from the dialog that appears. I click on Play and nothing seems to happen. I see a single sphere off in the distance.
  12. Simulation Cache

    The File node also has a Read,Write and Automatic drop down setting. When you know your are going to Write the final sim data, set it to Write. Then when the sim has completed set it to Read. This is kind of like a lock to prevent future overwrites on an expensive sim. While you are still tweaking parameters leave it on Automatic.
  13. Short and sweet OP centric lessons

    I have created another short tutorial on how to drive animation using sound. You can view it here:
  14. Hi All, I am trying to make a simple body of water, derived from a cube, splash around a medicine bottle. I created a FLIP tank to be the domain for the simulation. The bottle mesh is a rigid body object. I placed a cube in the FLIP tank as well and converted it to fluid to be the initial fluid for the tank. However, this does not work. The cube of fluid I created just falls out of the tank and does not recognize the walls of the FLIP tank. Does anyone know how to fix this problem? How do I let the fluid object know it is a participant in the FLIP tank? Thanks ap_bottle_splash_1a.hipnc
  15. I am still learning the FLIP system. So to increase fluid resolution do I decrease particle separation? Or is there another setting for turning up the fluid resolution?
  16. Thanks for the tips, I wondered about the multiple solvers. I thought Houdini just simply summed all that because the result gets routed to a single node. If I delete the FLIP tank and flipsolver2 my inital fluid just falls through the floor, no boundaries. In this example I have created cube based walls, an RDB floor and the bottle all as rigid body participants. This does keep the fluid inside the required area but I still can not get the fluid to avoid the bottle in the scene... ap_bottle_only_1b.hipnc
  17. I have NULL with a python script inside with a single print statement. At the object level of the NULL I have add a Button to the parameter interface. How do I link the code to the button? What do I put in the callback script field? Thanks
  18. Hi All, I am still trying to work out a flip tank scene. I have received feedback that I should try to maintain the correct scale for a fluid sim to "flow naturally". I have downloaded a Star Trek Enterprise model and scaled it to the sci-fi specs that the ship is 300 meters long. I have placed this rising up from bottom to top into a flip tank that is 600x300x600 with a particle separation of 4.25 (a coarse simulation). This all works, however, gravity seems to not be as effective when the flip solution is this large. I would like to keep gravity "real" at the -9.8 setting. I was hoping that the shelf tools had all the calculations linked up somehow. But I guess not. The scene is simple. I imported the model and animated it. I created a flip tank and pressed play. If you have time to take a look at the scene I am attaching it. Maybe there is some setting that can be tweaked to restore gravity's influence on the fluid? Thanks ap_tos_enterprise_rise_up_1a.hipnc
  19. Hi All, I CTRL-CLICK to create a box at world origin. I use SPACEBAR-2 followed by SPACEBAR-G to zoom in on the box. I notice it covers 2 construction grid units. I have read in a few places that one Houdini unit is 1 meter. Does that mean one numerical unit (parameter value) is 1 meter or one visual grid unit is one meter? I want to create a FLIP tank that covers about 600 meters. Would I type in 600 for the size of the box or 300?
  20. I have a Translate [X] curve in the Channel Editor. I box select one of the keyframes. I click the Handle Untie button on the right hand tool shelf but the handles do not untie? I want to change my tangent handles independently. How do I untie handles?
  21. So what good is the callback script? I still don't get it. If I can only put one line in the callback field what good is it?
  22. Thank you, so it is numerical parameter based.
  23. Hi All, Just a quick general question. Does Houdini have a dopesheet? I have been wondering how to reposition keyframes, in time, after I have already added them. Currently I have been just deleting the entire channel and re-creating them as needed but I do like the Dopesheet view that other applications offer.
  24. Houdini Dopesheet?

    Thank you, I guess that view has multiple functions.
  25. I don't think I misunderstand python completely. I already have a scene generator working in the Python Source Editor. Perhaps HDA is the way to go, but what I am trying to accomplish is to simply add some interface controls to my existing script. I thought if I could just place it in a NULL and then add a button that would work. Then I could I add some parameters to the interface to route to my existing variables in the script. NOTE: My code is not generating geometry within the node, it is creating an entire scene. For example I expect to be able to issue a hou.createNode() anywhere within Houdini. Even if it is considered a poor practice, it should work, correct? So within the example image shown below I could put a line of code that created a subnet at the /obj level. That, of course, has nothing to do with the SOP level of the NULL where the code is executing. I am just looking for a container with a button and some parameters. The Source Editor Window does not offer that ASFAIK. My Steps So Far: Create a NULL. Dive Inside. Delete what is there. Add a Python Node. So the button sits one level up, and so would the parameters. The script sits inside. Why is this asking for the moon? Houdini clearly supports this setup because I can create it. I just need a way to call my main() and reference external parameters. @fathom I thought I was creating a normal python module using the steps I mentioned above? What do you call a normal python module and where does it reside within the Houdini scene? I already have code within the Python Source Editor is that what you mean?