1. Hi Christopher,
    Thank you for your course !

    I’m having an issue with some hair getting stuck inside the torus collider at the beginning of the simulation.

    I tried increasing the collision passes, then the constraint iterations and finally the substeps up to 5 but none of this solved the problem.

    I then animated the scale of the torus to go from 0 to 1 over a few of the 1st frames and it kind of worked but I still get some glitches at the start. And now the animation isn’t looping properly anymore.

    How would you approach solving this ?

    Thanks for your help !

    • Hey Damien,
      The hairs are probably getting stuck because they’re intersecting right at frame 1, so making collisions more accurate won’t fix this problem. The solution I’d use is keyframe the first radius on your torus node: Start out with a large torus, that won’t interect with any hair and then, over the next 15 frames or so, animate it smaller so it starts colliding with the hairs. You can get rid of this lead-in animation with a Time Shift node at the very bottom of the setup: Just write “$F + 15” in the expression on the Frame parameter of that node, to shift the entire timing back 15 frames or the length of your lead in animation.

      Making this a looping animation is a bit more involved though and I will cover this in a future video.


  2. Hi Christopher,
    Thank you so much for your reply !
    I’ll try this 🙂

  3. Question – I had originally started this by just using a torus geo – rather than drawing out a spline and sweeping it to get the main flower shape. However I noticed when I got to the simulation vellum hair part – the hair was acting much differently. Very stiff – something was off about it. I had to turn the stiffness settings WAY down for it to seem like any gravity was happening.

    I then went and created the spline and sweeped it and hair started acting as you’d expect it to

    Is there a reason for this?

    • Hey Brandon, I can’t see any obvious reason why a different scattering surface would influence the stiffness of those vellum hairs. Here’s a couple of things I’d investigate in debugging this: Does the overall size of the torus drastically differ from the sweep? Are there any differences in attributes on both objects (attributes are covered in the next round of episodes after this one)? Particulary an attrib like “pscale” or “width” might change the thickness of those vellum hairs, making them behave differently. Finally take a closer look at the vellum sim: Are those hairs intersecting to much with the torus collision object? Does the hair thickness drastically differ? Those might all be reasons for this strange behaviour.

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