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About drossxyu

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  • Name
    Frank Grecco
  • Location
    New Jersey
  1. I'm trying to figure out an efficient way of snapping lights to my headlight geometry on an exported alembic. The alembic is being exported outside of Houdini. I have 18 pieces of geometry that need lights attached and one way of doing this would involve creating a point group at the SOP level for each one and creating a corresponding rivet object that will parent the lights. Since the rivet object takes the average of each point in the point group I have to create 18 solo point groups ( as far as I understand ). Is there a better way of doing this? If I export my alembic with the vehicle at the origin on a frame before the animation starts perhaps I can place all of my lights once and have just one point/rivet combination. I'm trying to avoid this workflow as adding this extra frame will become a bit of a nuisance as the animation is changing frequently.
  2. FLIP and Bullet Interaction Troubleshooting

    Here's another question: When I read my simulation back into SOPs I have both a Dop Import Fields to bring in my FLIP data (Geometry, surface and vel fields) and a separate Dop Import to bring in my simulated rbdobject1 rubber toy (set to fetch geometry). I'm writing both of these imports using separate rop_geometry_output nodes but it seems like it's having to calculate the sim twice. Is there any way around this? Seems redundant.
  3. FLIP and Bullet Interaction Troubleshooting

    This is working a lot better! Thank you. One thing I noticed is that you're using the default "Ray Intersect" method for your RBD Object DOP collision method. This seems to work fine. What I don't understand is why I'm unable to successfully prepare my collision SDF for the rubber toy in SOPs without strange results. I did a simple conversion of the rubber toy with a vdbFromPolygons set to surface, set my RBD Object DOP to "volume sample", and pointed the volume proxy to this output. You can see below that the toy just flickers in and out of existence and ultimately disappears. I also prepared my collision geometry for the bullet collisions by fracturing it first so that I can have more accurate RBD collisions but as you can see with the "Ray Intersect" method it sees the fractured geometry and creates a weird and i'm assuming inaccurate collision volume. https://streamable.com/v1y28
  4. I've been trying to get a grasp on the FLIP workflow for the past 2 weeks or so and one thing i'm having trouble wrapping my head around is how to have my RBD toy object react elegantly to the FLIP simulation. It always seems to move in an erratic way with lots of weird little jitters and bumps yet the FLIP fluid beneath it appears to be pretty smooth. My scene scale is realistic. The baby pool is 3m in diameter I've tried lowering my collision separation to match my particle separation (currently 0.01). I had to lower this considerably to keep the water from leaking out of the bottom of the pool. Feedback scale is set to 1. The Density of the toy is lower than the water (50 vs 1000) I've tried increasing the overall substeps to 2 on the dopnet itself but it did not seem to make a difference. I used a convex decomposition on the toy to turn it into a bunch of packed convex pieces. It's set to convex hull in the RBD Packet Object bullet data options. Maybe this is the problem here? I don't see a way to create a volume representation of the toy. The pool and the ground are both static objects prepared as an SDF in SOPs and set to “Volume Sample”. I increased their uniform subdivisions to 60. I've attached the file if anyone has time to help me investigate. Cheers! https://streamable.com/s/7pwh4/mwtako flipToyTest_v3.hiplc
  5. 1) Is there a way to only affect the tip of your guide curves when using the groom brush? It’s easy to grab the center of the guide curve which ends up bending them in an odd way that’s counter to the direction I’m attempting to brush the curves in. If I make my brush small enough and position my camera strategically I can of course just graze the very top of the curve but it becomes difficult when there’s a lot of guide hairs. Additionally, If I use the curve advect tool I notice that all of the guide curves that have been advected have a concave bend to them similar to if I had used the screen brush on the center of the curve instead of the tip as I mentioned above. 2) Is there a way to pop hairs out that have flipped through the other side of the surface? If I do a simple fur setup on a grid it’s very easy for this to happen with a few strokes of the screen brush. 3) Are there recommended ways to optimize the viewport when grooming? It seems really sluggish even with a modest amount of guide hairs once you start adding a few guide process nodes. My hair generate node is off of course. 4) After I place a guide groom node and use the plant guides tool to create a few custom guides the guide groom density no longer has an effect if a raise or lower the value. If I disable the planted guides, it works again. Actually I’m realizing now that even doing a groom with the screen brush seems to lock that initial guide count into place. Is this the intended behavior? 5) When using the Hair Clump node it seems like mixing the blend value to 0 doesn’t actually turn the effect off entirely. With default settings and blend set to 0 I still see very obvious clumping. It’s not until I set the fractal clumping iterations to 0 does it act as if I disabled the node entirely. With fractal clumping set to 0 and the blend set back to 1 though, the settings in the general tab (clump size, crossover rate, etc) do absolutely nothing. 6) Is there a trick to setting the influence radius and decay values in relation to both the guide curve and hair generation density? It seems heavily dependent upon how many guide curves I have of course but I’m finding that’s easy for me to end up with a look that’s too clump-y without actually having a clump node in my setup. If I raise the influence radius higher to move away from the clump-y look it starts to lose any variation I may have added to length, bend and frizz. If I come up with something that's look pretty promising with a low hair generation density I'm usually surprised at how different feeling it looks once I start to really crank the density values. Cheers!