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Everything posted by eimk

  1. Universal gravitation simulation

    Sebastian Lague's stuff is really cool - you have great taste. His code can be translated pretty much directly into VEX; sqrMagnitude becomes length2(), normalized becomes normalize(), and the equivalent of timeStep is the @TimeInc attribute. The key part is putting it inside a solver so the positions are updated each frame, based on their positions from the previous frame. Here's my attempt: (I'll post the file if you're still having trouble but it's a bit messy)
  2. Constraints broken in Houdini 18.0.532

    Promote the 'name' attribute from primitive to point after packing and the constraint will work.
  3. Even shorter version: @P = lerp(@P, @opinput1_P, ch("mix"));
  4. uvtexture camera preojection

    Seems like your geometry just needs more divisions. Here's the UVs from your original scene file: They look really distorted here. If the divisions on the larger box and the tube are increased, that distortion goes away:
  5. This seems to be a problem with the normals. If you add normals to the points with a normal or polyframe node before the copy to points they won't jump.
  6. If you don't need any of the other functionality of the attribute transfer node, it would be faster to use a wrangle: @P = @opinput1_P; (line into input 0, edit into input 1)
  7. Can I use the CHOP nodes to deform a line?

    This is a good introduction to CHOPs, maybe it can help: https://www.tokeru.com/cgwiki/index.php?title=HoudiniChops
  8. Add AOVs to ROP

    Use the insertMultiParmInstance() function on the AOVs parameter
  9. Procedurally split faces

    There's probably loads of ways to do this, but here's one: split_polys.hipnc
  10. In the volume wrangle you need to specify that 'h' is a vector by using 'v@h' rather than just '@h'. VEX assumes everything is a float unless told otherwise, or if it is one of a few specific attributes like Cd. This page has some helpful info on attributes in VEX https://www.sidefx.com/docs/houdini/vex/snippets#attributes
  11. Vellum Solver is deleting Cd point values?

    There isn't an attribute randomize in this scene file. Are you sure you attached the right version? Anyway it seems to work fine if I add one, directly after the scatter node.
  12. Vortex Cloud Simulation

    My computer doesn't have enough RAM to run your sim without Houdini crashing, but my best guess for what could help would be decreasing the strength of your velocity field and/or adding a drag force. Alternatively you could look into the vortex force node, which might be easier to work with than your current setup. https://www.sidefx.com/docs/houdini/nodes/dop/vortexforce https://www.sidefx.com/docs/houdini/nodes/sop/vortexforceattribs.html
  13. The VDB conversion and advection was just to make the volume change over time for demo purposes since I didn't have your .hip to work with. The POP Advect by Volumes node will work with any volume, so it should be fine with your wrangle.
  14. Vortex Cloud Simulation

    I don't know what your setup is, but if you keep the forces constant eventually they will balance out with air resistance and the velocity will become constant too. If the forces keep increasing the sim could get chaotic and difficult to manage.
  15. Your problem is with the trail increment. You'll get this error unless it is a multiple of 1 divided by the simulation substeps. So since your sim has 1 substep the trail increment has to be a multiple of 1. If you had 5 substeps it would have to be a multiple of 0.2 etc.
  16. POP Advect by Volumes is probably what you're looking for particle_advection.hipnc
  17. Baking (Redefining lo-poly mesh / chamfer?)

    If you turn on 'Ignore Flat Edges' in the bevel node and increase the angle you'll get rid of the unnecessary beveled edges and the remaining ones should be cleaner. Increasing divisions to 2 might also help with the corners. If there are still non-manifold edges etc the clean node might be able to fix that.
  18. Vortex Cloud Simulation

    This is likely a result of linear/tangential velocity increasing while the centripetal force remains the same. The equation F=mv2/R, where F is centripetal force, m is mass, v is linear/tangential velocity, and R is the radius, shows that if F and m remain constant and v increases then the radius must also increase. Linear/tangential velocity increases because the force(s) acting on the smoke cause an acceleration, which is why it starts moving in the first place. I haven't tested this, but if you decrease the force(s) causing it to spin it will take longer to get up to the speed you want, but then I think it will settle at a smaller radius.
  19. not entirely sure what youre wanting but hopefully this helps: shop_materialpath.hipnc shop_materialpath_py.txt assuming all of your geometry has a shop_materialpath attribute, the wrangle will create a group for each then if you run the code in the source editor (if its not already there paste in the txt file) it will create a new material in /mat for each group, and add each group and corresponding shop_materialpath to the material node