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About ChrisCousins

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    Chris Cousins
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  1. Hiya - apologies for dumping all my problems on this forum - I've run into a problem with making a vellum sim loop. Rough version here: https://www.dropbox.com/s/1c6k2pfeou0b7qw/product03_cloudyFun.[0001-0125].mp4?raw=1 I've got a simple vellum soft-body thing, and it returns to roughly the same state as it begins, and I'm trying to get it to loop. Positions are pretty ok, the trouble is that the objects have rotated quite a bit during the animation, so using blend to get back to the start position makes the pieces invert or squish. Some aren't so bad, but some go inside out which is no good. Hope someone can give me some pointers, if this is even possible? Thanks! C
  2. Making rings around a sphere

    Thanks Tim. And fancy meeting you here! And yup you're right it's a whole new world ;-)
  3. Hiya - short version of this is that I've got a scene with deforming volumes (clouds) using volume deform along a series of curves etc, and want to render in Karma (XPU). All works fine the renders are pretty and very quick but motion blur is missing on the volumes - I'm assuming I need some velocity info on the volume. So basically I'm looking for a sort of Trails sop, to calculate velocity, but for volumes, or maybe there's another simpler solution?
  4. Making rings around a sphere

    Result: Thanks again!
  5. Making rings around a sphere

    Magic - thanks so much! SOPs is so deep, I keep losing stuff....
  6. Hi - I've got a feeling there's a node somewhere that does this as one of its options, but I can't remember where/how. Basically I want to take a sphere and connect longitudinal lines around it, to form rings like this: I've got a simple setup going where I'm manually connecting points and polywiring them into rings - but it feels clunky, and isn't very procedural! I'd like the rings to be closer/denser too, so there would be tons of loops to connect. Plan is to do some sort of soft-body thing with the polygon sphere and use point deform to make the hoopy version follow along. Or something... Hope there's a nice solution! Thanks :-)
  7. Hi - hope someone can help. I've got a crowd sim that I'm trying to migrate from Mantra to Karma. In Mantra the materials work via style sheets, works fine. In Solaris, the problem seems to be that agent geo isn't accessible. I can assign a material per agent, but can't access the sub-geometry to get different materials on clothing, hair etc. Here's the scene graph - I've got all agents called 'Suzie' just for testing purposes. The string '/sopcrowdimport1/suzie*' correctly selects all the character geometry. However I can't get it to select the components; using '*default_Ch41_Hair*' selects nothing. This is my first proj using solaris (as you might notice...) so hopefully there's a basic fix ;-) Cheers -- Chris
  8. Particles all drift the same way

    Update - heard back from sidefx, helpful and speedy as ever. I'll quote it rather than mangling it with my own interpretation ;-) From our developers: The particles do per-triangle collision, so have the chance of colliding at the edge of a triangle rather than a face, thus imparting horziontal motion. This is because they are colliding with a soup of polygons, not with a mesh. The other strong artifact in this situation is that particles get a default radius of 0.02 if no pscale is set. This is why if you scale this system up 10x (by transforming source, collision, and gravity) it will seem to work. Alternatively, you can set pscale to 0.002 on the particles to get less silly behaviour.
  9. Particles all drift the same way

    On it...
  10. Particles all drift the same way

    Thanks for looking into this. Yup the setup I had in mind needed a dense grid, the idea was that the collider has attributes like bounce, friction that can change over time, allowing the sand to settle in patterns, and shift as the attributes shift - but they always just run off the edge in one direction unless I turn up friction so high they just get stuck. Hmmm... I guess there must be other ways of getting the motion I'm looking for, maybe using point clouds and getting the data via nearpoint() - will take a look. Strange that POP is affected by topology in this way, but I guess the optimisations have to come with certain limitations. Thanks again - Chris
  11. Particles all drift the same way

    Thanks Dennis - nice idea but no dice, they all still dutifully roll the same way. It needs to be geo they're bouncing off as I'm planning on adding variations like friction, v etc to the plane, to get the particles bouncing in certain ways (think sand on a chladni plate). Appreciate the suggestion however! Cheers - Chris
  12. Particles all drift the same way

    Hi - hope there's a simple answer here. I've got particles on a plane, which I'm planning to add forces, friction attribs to so the particles all tend to drift in certain ways. What I've noticed though is that even with a totally flat grid, the particles initially bounce straight up but once the vertical movement stops they all drift in the same direction. See silly GIF attached. I'm guessing a rounding error, substeps don't help but is there any way to avoid this? I thought using a planar patch not grid would fix it, but they just move in different ways but still the same direction. Plane is not rotated, no forces other than gravity... help! HIP attached. Cheers - Chris sillyParticles.zip
  13. Instancing multiple objects onto DOP simulation

    Thanks for laying it out so clearly vtrvtr - all makes sense. By doing it with instances I was hoping to avoid the memory overhead of using duplicated copies of the same geo. Instances just seem super-efficient, but it became more of a headache than it was worth. I've had a quick poke through your file though and using 'Pack and Instance' option on the high-res side of 'copy to points' does this automatically, and doesn't seem to affect naming process, so they all still match up nicely. So -- solved! :-) Thanks again - Chris
  14. Instancing multiple objects onto DOP simulation

    A bit of progress! Did some reading up, and found the problem with the positions was that they needed to be taken from the packedfulltransform intrinsic. So… matrix m4 = primintrinsic(0,'packedfulltransform',@ptnum); matrix3 m3 = matrix3(m4); @orient = quaternion(m3); v@pivot = primintrinsic(0,'pivot',@ptnum); Last problem to fix is that the rotations don't update - the orient value stays 0,0,0. Grateful for any assistance! Cheers - Chris
  15. Instancing multiple objects onto DOP simulation

    Thanks for the reply. Cached on uncached doesn't seem to fix the problem. I've made a very simple chopped down version of the file, attached. I've got a feeling that the problem lies in extracting the intial transformations of the points, hoping there's a silly setting I've overlooked. SimpleInstanceSetup.hiplc