Jump to content


  • Posts

  • Joined

  • Last visited

  • Days Won


StepbyStepVFX last won the day on March 27 2022

StepbyStepVFX had the most liked content!


Contact Methods

  • Website URL

Personal Information

  • Name
  • Location
  • Interests
    VFX, Computer Graphics, AI, Deep Learning, Cinema and many more...

Recent Profile Visitors

2,327 profile views

StepbyStepVFX's Achievements


Newbie (1/14)

  • Week One Done Rare
  • One Month Later Rare
  • One Year In Rare

Recent Badges



  1. Well, I don’t really understand the need so hard to orient you in the right direction, but maybe with a bunch of switch nodes and timeshift node ? Really depends on what you need to achieve.
  2. The way Houdini works is that it evaluates nodes from top to bottom of your node-graph (well, in SOPs : not talking about DOP or PDG...). Therefore, each frame, your graph is re-evaluated independently of the previous frame.... until you use a SOP Solver node. The SOP Solver node allows you (when you dive inside him), to access (i) the incoming stream of nodes, evaluated at this particular frame and (ii) the same stream of nodes, evaluated at the previous frame. Therefore, you can perform your code on the incoming stream, make your tests and create geometry, and then merge it to the geometry of the previous frame. It allows you to keep changes you made on the geometry on previous frames (because each frame you can merge what you are doing with the results of previous frames). Here some docs : https://www.sidefx.com/docs/houdini/nodes/sop/solver.html
  3. Hi All, The interaction between Crowd agents and FLIP simulation is one way : agents clearly influence the FLIP Simulation, but I have troubles to get the FLIP Sim move my ragdoll agents. I have already put the Feedback Scale to 1 under FLIPSOlver / Volume Motion tab / Solver. I have seen that particles interact with ragdoll agents, so I have created a POP object and added a POP Solver. The POP object is feed with the particles of the FLIP fluid at every simulation time. And I add a mass and pscale attributes to the particles. Now I have a better interaction between the ragdolls and the FLIP sim... but my agents now start to act as "spaghettis" under impacts of particles... I have tweaked the constraints (CFM, position CFM, position ERP etc.) but I can't enforce the position constraints and my ragdoll are really streched... Any ideas how to solve that ? Maybe a better way to make FLIP and crowd ragdolls better interact ? Any video / course / lesson / ressource where people have played with that a bit ? Thanks for your help crowdFLIPtest_v1.hip
  4. Guys, I am not a developper by any means, but from what I understand, and "API" is an Application Programming Interface, which means it requires an instance of your application to be run in any case (Houdini, Maya...). The module you use "HOU" is just a library of functions that Python (or C++ in case of SDK) understands and calls the application (Houdini, Maya...). So it is really just an "interface" between standard programming language and an application. I guess you can run an instance of your application in "command line" (Houdini or Maya with no GUI) and use that / declare it from a standard Python file executed in Python, and from there it should work. But to don't ask my how, never tried with Houdini or Maya.
  5. Any idea of how to make this dynamic constraint creation setup works ?
  6. Have you tried to time blend the source (before the Debris Sop) ? And as said by Eric, if you cache the source, be sure to cache inter-frame as well ( see post below) https://www.sidefx.com/docs/houdini/nodes/sop/timeblend.html
  7. Do you just need a wet map, or do you want to recreate the Substance dynamic brush where you paint with particles ? For getting wet maps, you can find plenty of tutorials on google : https://www.youtube.com/watch?v=XEeZ6a56kC8 and : https://vimeo.com/channels/pqhoudini/285813013
  8. Good evening, Following my studies on crowds systems, and a question from @jackassol about sticking ragdolls to colliders, I have tried to create constraints on the fly during the simulation, using Impact data. My first attempt being a quasi-failure (see attached testRagdollDynCon_v1.hip), I have tried with a simpler setup : a sphere rolling over cubes, and when hitting cubes, creating constraints on the impact data. You can see my test file attached as well : dynConTest.hip This, again, being not satisfaying, I have tried with a much more simpler setup : 2 cubes sliding on a plane and "joining" where impact occurs. AND IT WORKS !! (see file dynConTest_basics_v2.hip) Now, I really have a hard time figuring out why my setup dynConTest_basics doesn't work... I am afraid this comes from bad matrix inversion / rounding errors (I use an inversed fullpackedtransform to bring the impact position back to the "initial object space" of the sphere). Does anyone have any idea on where the problem is ? Thanks for your help ! testRagdollDynCon_v1.hip dynConTest_basics_v2.hip
  9. Well, this would require a bit of VEX, but I guess the main elements to achieve would be : - I would work with a polygonal version of your collider (I don’t know what it is you are using, but you can always « hack » your DOP object and add pieces of data inside : check my other hip file, you will see that I need polygonal version of my terrain https://forums.odforce.net/applications/core/interface/file/attachment.php?id=49690 - you can use the Impact data (basically points), to find the prim and uv where the impact occured on your collider - use these to always reference the point on this moving geometry where impact occured, and use this point to modifiy the constraint anchor in the sop solver of the constraint network Of course, you will need to be familiar with Wrangle and SOP Solver and how to call different pieces of data in DOP... (all the bindings etc.) Check the hip files I shared, because the main ingredients are there, you just need to spend some time figuring out, step by step, how to reference a point in DOP context, and use this position to modify a constraint network.
  10. Indeed, FLIP works best for mid/large scale sims. I think a ripple solver, plus some custom particle system can do the trick. Just in case you would need some ref for a ripple solver, Entagma did a series of videos 2 years ago :
  • Create New...