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About jamesearnest244

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    James Earnest
  1. Counteracting Force Accumulation

    Hi, Forces in DOPS tend to accumulate and get stronger and stronger over time. I guess that makes sense in a way, but in many situations this is not wanted. For example, when using a Curve Force or POP Axis Force - you often want the force to affect your objects predictably and not lose control. Is there a way to limit the accumulating behavior when using forces? I often resort to VEX/VOPS to control velocity directly, but it can get pretty hard. Forces offer a lot of handy behaviours, I just wish they were more controllable - any tips? Thanks!
  2. Voronoi Messes Up Normals

    Thanks, but I get the same issue when fracturing manually with the Voronoi Fracture node.
  3. Voronoi Messes Up Normals

    Hi, I have a model that renders fine unfractured, but once I've fractured it, I get shading artifcats from bad normals. It looks like Houdini is inferring normals for the new vertices by interpolating between neighboring ones, but it's not looking right. I've tried using an Attribute Transfer SOP to take the normals from the pre-fractured model, and it helps a little but doesn't solve it completely. Also tried the cupsing settings on the Facet SOP and Vertex SOP. I'm stuck. Does anyone have an idea how to fix this? I'm not doing any fancy fracturing, just the RBD Material Fracture node. Thanks!
  4. Scale Bullet Collisions

    Hi, Is there a way to scale the collisions in bullet sims, like you can in FLIP? I have a slow-moving collider, but I want the impact it creates to be more forceful. Thanks!
  5. Inherit SOP Animation in DOPS

  6. Inherit SOP Animation in DOPS

    Hi, I have some fractured geometry in SOPS. I want to animate the geometry in SOPS, and have that motion inherited within DOPS, so that the geometry breaks when it encounters collisions along its path on the SOP animation. In some programs this is called a Kinematic rigid body - you control the movement of the object as a whole using traditional keyframes, and these keyframes give the simulation implicit velocity data to base the dynamics off of. Does anyone have an idea how this can be done? Thanks!
  7. What Is Time Scale, Really?

    Hi, I'm confused about what the Time Scale parameter on different solvers actually does. The documentation is kind of vague - "scales the timestamp used by the solver". But it doesn't just slow down the sim, it actually changes the behavior in ways that I haven't been able to consistently understand. So I'm wondering what I'm actually telling the sim to do by changing this parameter. Thanks!
  8. Hi, I have a piece of geometry and I want to have curves running all through it. I've made a VDB and scattered points into it, which I've connected into polylines with a Connect Adjacent Pieces SOP. I'm trying to turn these straight lines into curvy, flowing ones. If I just resample them as subdivision curves it doesn't work, because the straight segments aren't connected to each other. I think I need a way to connect polylines at random locations, so I can then resample them. Any ideas? Thanks!
  9. Replacing Proxy with Hi-Res Geometry

  10. Replacing Proxy with Hi-Res Geometry

    Hi, I need some help with replacing low-res geo with hi-res models after simming. I'm using the option "Create Points to Represent Objects" in the DOP Import node, but the hi-res geo that I copy onto the points isn't orienting itself properly. Help appreciated. Thanks! proxy-hires_sim.hipnc
  11. Accessing Bullet Impact Data in DOPS

  12. Accessing Bullet Impact Data in DOPS

    Basically yes, but I'm using packed RBDs in Bullet, so we're talking about grouping points, not RBD objects.
  13. Accessing Bullet Impact Data in DOPS

    Thanks very much! But this isn't quite what I'm after. I want to use the Impact data in DOPS, not in SOPS. I want to create POP groups of points in the RBD sim, based on the number of times they've collided with the ground plane.
  14. Accessing Bullet Impact Data in DOPS

    Hi, I have a simple Bullet sim with an RBD Packed Object node. I would like to create POP groups based on the points' collision data. For example, group the points that have collided with the ground plane more than once. I know I can access the impact data with a SOP Solver connected to the Bullet Solver, but I'm not sure how to use the data there to set up the POP groups. Very simple setup attached to make it clear. I'd appreciate any help! Thanks! Impact Data.hipnc
  15. Hi, There's something I'm not quite getting about animating deformations. In this screenshot, I want to rotate the selected primitive about the X axis, after having snapped the gizmo to the adjacent edge using the align state (;). But you can see the values in the parameter window going all over the place, resulting in weird animation. I was able to get around this by moving the primitive to the origin, animating it there, and transforming it back to the original location, but surely that's the dumb way of doing it. Why is this happening and how do I get it working right? Thanks!