Jump to content


  • Content count

  • Donations

    0.00 CAD 
  • Joined

  • Last visited

Community Reputation

0 Neutral

About vfxstu

  • Rank

Personal Information

  • Name
    Stuart Griese
  1. Using the FEM Solver for car crash / destruction

    I recently had to do a car crash and used this approach as well. I'm not sure if all the attributes are the same as the ones on the link you provided, but here: http://www.sidefx.com/docs/houdini/nodes/dop/finiteelementsolver-.html about a third of the way down the page they are listed. I found that you need to apply these attributes onto the tet's as point attributes for them to work. My big picture workflow for the crash was to simulate a low-res car frame with varied FEM attributes and some clever keyframing, then use cloth capture to deform the high-res frame. Based on that I pinned the edges of some low-res windows/windshields to it with pintoanimation and simmed them as FEM, then also cloth captured that geo's hi-res version. This gave me glass that bent and curled, which I needed for a shatterproof glass effect. To do that I timeshifted my hi-res windshield geo to $FEND and did some stuff to figure out most bent angles, then set a density based on that and used it with a Voronoi fracture back on the original rest geo. Then I made each piece of glass transform with the deforming hi-res windshield. Using that same attribute that determined the most bent angles, I released some pieces into an RBD sim at the point of impact. Not sure if you needed/wanted any of that, but it was fresh in my mind.
  2. Sometimes I've run into Volume lights locking up as well, usually just have to make new one with the shelf to get it to work. Not sure why your Geometry light wouldn't work though, can't check out your scene currently, but if you need something right now you can always find the pt number of a central pt of the Geo (before it's turned into Volume) and then reference that pt's position on a normal light. So for example if your source geo is at /obj/spirit/source_geo, and pt 40 is around where you want the light. Make a light and use this expression in position x: point("/obj/spirit/source_geo",40,"P",0) For position Y and Z change the 0 to 1 and 2 for the correct indexes.
  3. Also in Vops we have Non-Deterministic Random node, and VEX nrandom( ) function.
  4. Constraints mixing pops and bullet

    Wow that's really awesome! Would love to see how you did it if possible.
  5. For anyone running into this same thing - if you want to use attributes that get updated inside a Sop Solver in DOPS, you can access them in DOPS with a Geometry VOP or POP VOP (if packed geo) and set one of the Inputs path to the geo from your Sop Solver. Then inside the vop net use a Get Attribute and wire it to the input you set and use the current pt/prim num. Took me too long to figure this out.
  6. Hi, if anyone has a second to look at this it would be very appreciated. Im working on a paintball effect and have the balls (just shell for now) continuously entering the sim in a SOP Solver. The constraints strength is -1 until the ball is close to the collider, then the SOP Solver updates the 'strength' attribute to .001 so they break. That's working fine. But now I want a percentage of the shell to freeze on the wall (later will try to have this interact with some viscous FLIP), so I set a boolean in SOPS called 'stick' and in my SOP Solver I do a check to see if the piece is not constrained and has 'stick' of 1, then set a new boolean 'freeze'. I can see in my Geo spreadsheet in SOP Solver the 'freeze' attribute is working properly, but this is where I'm messing something up, I can't figure out how to use that attribute outside of the SOP Solver in DOPs... shouldn't I be able to call it anywhere I can use VEX? I also tried the same technique to set the 'active' attribute and it didn't do anything. I've tried making POP Groups with VEX: ingroup = i@freeze; and then setting all velocity to 0,0,0 based on that and it didn't do anything. Is my problem that DOPS doesn't directly import and update the attributes set in the SOP Solver? Am I going about this the wrong way? There's gotta be an easy way to do this! splatball_dev1.mov splatball_OF_v001.hiplc
  7. Hi, bit confused how I would go about setting a conditional statement (like you do in the 'Hide When' field) but for my default value? Anyone done this? edit: yea i was overthinking that, just needed to type a normal if statement expression in for the default.
  8. Hi - so I have a particle system (from popnet old) of particles basically ramming into their nearest neighbor if their nearest neighbors nearest neighbor is them... and then I have one of the particles being deleted when they're about to collide. Now I want to do an RBD sim of spheres colliding with fractured spheres. So I separated the points into two groups, one for points that are acting as colliders which get spheres copied to them, and another group of points that exist for one frame (right before the collision) that get fractured spheres copied to them. I tried bringing these into a dopnet and making two RBD fractured objects... probably going wrong right about here.. The first RBD fractured object I set as my collider spheres and set it to 'Use Deforming Geometry' and the creation frame to $FSTART. When I watch it alone the animation seems to be working and the collision geo looks good. Then the other RBD fractured object I set to my fractured spheres and set the creation frame to $FF, when I watch this alone it seems to be working too. However when I merge them and plug them into a bullet solver everything goes crazy. I'm probably missing something simple, but I've been stuck for awhile now so figured I'd finally make my first post on here! The Hip file is attached, thanks in advance! particle_system_smash_test.hipnc