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About shawn_kearney

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  • Name Shawn

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  1. A simple framework to permit deformations on volumes, if not the facilities to sculpt directly onto SDF would be kind of cool. Does anything like this currently exist?? I know that there are volume paint tools.
  2. As far as I know you can't; not directly. You need to use deep rendering for this. If you're using arnold, then I am pretty certain that's the only way. It sounds a lot scarier than it is though.
  3. I've known about clustering, but it makes sense now how clustering can help here. I've always thought of clusters more thinking in terms of the dynamics and how the fracture plays out, I wasn't really thinking of it in terms of the overall shape of the pieces. You've given me a lot to think about.
  4. Awesome reply, @jonmoore
  5. First of all, I'm not doubting you at all. As popular as Voronoi is and as new as I am to Houdini I feel like I must be overlooking things. Even asking this makes me feel foolish. But one reason I'm wondering is because in Jeff Wolverton's Image-based Destruction tutorial he mentioned off-hand that there are better ways to do fracture, but did not discuss what those were (FEM seems like it'd be overkill). Perhaps it was some other approach to Voronoi (i.e. RBD Fracture), but it seemed like he didn't care for Voronoi in general. But I have used Voronoi some, and by comparison VDB Fracture SOP is generally faster both in set up and performance for complex interior noise, and much easier to control (though large numbers of small, detailed pieces are still problematic, though so is true of voronoi). Add a platonic, subdivide, copy onto point and displace points with mountain sop. I can control the exact shape, placement, size and interior noise of pieces with a high degree of visual feedback before cutting up fractures. Yes, from my limited experience I can get the same results when doing a basic fracture as explained above. Buteven for a basic random fracture VDB fracture just seems more responsive and direct. Like I said, probably I'm missing something. I'm just not sure what it would be. VDB fracture is a SOP that cuts SDFs into multiple primitives based on mesh input. You then use Convert VDB sop to import into DOP normally. It's not immediately obvious how it all works and there aren't many tutorials out there.
  6. I figured my method would be inefficient since I had to copy all the geometry for each iteration. I'll be sure to take a look at your hip later.
  7. Slight improvement to my version to account for part the centering of pieces, and got rid of some weirdness in VOP. Not sure if this is possible without a for-each (is it?). Mine works by attributing one random piece to a group called "sel" and using that group to define the source group on the copy SOP. The seed for the random selection is based on the point number of the template point. This point number though is lost inside the for-each since it only brings in one point at a time, so it must be written to the "id" point attribute piror. I then multiplied the random number generated (which is between 0-1) by the total number of packed primitives and converted it to an integer. Now I have a random integer that corresponds to a single packed primitive. I use this index number to assign the primitive to the group "sel" So for this iteration I have one randomly selected packed primitive belonging to the group "sel" which I can use as the source group. In practice I'd probably do it a little differently and instead delete all but the selected and transform to the point, orienting to normal if needed and skipping the copy sop entirely. randomselection.hiplc
  8. I'm pretty new with houdini, so I am sure there is a better way. randomselection.hiplc
  9. I'm sorry if my newb is showing, but I am curious about people's thoughts on this. Now that I have VDB Fracture working, I cannot really see myself using Voronoi fracture in SOP (ETA - What I mean here is as opposed to RBD Fracture). Am I just missing out on something important, or is VDB just the way to go? When would Voronoi be the better choice?
  10. @marty I thoroughly see why this is problematic now. So yes, I'm with you all on bringing plastic deform to FEM!
  11. I made one and realized what I had to do... MAKE A WHOLE BUNCH! Simple wire solver using Empty Object DOP set to activate every 5th frame up until 160-something and imported using SOP Geo. Randomized initial velocities. Retimed using Timewarp SOP post-sim. Not sure I'll continue, but it was fun.
  12. Just to clarify, I do not mean to imply there is anything wrong with tutorials. But I think it's better to watch a tutorial with a specific problem in mind than to replicate what the tutorial is doing verbatim. At the Blender community we get a lot of people with zero experience at all with 3D and there is this sort of trap that we see happen a lot where people kind of get it in their heads that if they watch enough tutorials they'll be able to do anything. A much more valuable approach would be to watch tutorials that relate to something you're doing and apply what you've learned. This is why I really like entagma because what they offer feels more applicable to a broad range of problems.
  13. I am also new to Houdini. My approach is pretty much thinking of vfx problems and trying to find a good way to solve them. My university program does not support Houdini, so I have been doing it all on my own as independent study. Last semester I did four assets that represent Fire, Earth, Wind and Water. But pretty much the way I learn is to think "how would I achieve this?" if the answer is not immediately clear, I just set out to do it. Right now I am looking at how to drive rigid simulations directly using pyro. From there I have a bunch of other questions that need to be answered: how do I apply the pyro velocity to to RBD or FEM? If RBD or FEM the better choice? How do I get better results out of VDB Fracture? What is the best approach to creating a crater from an explosion? Answering these questions goes on to finding more interesting effects. For example, in trying to get the crater to work I discovered a way to simulate burning away/melting geometry that is extremely efficient and this weird effect where a fire burns downward, boring a tunnel as it goes - as well as the original problem of creating a crater left over by the explosion. For me anyway, solving my own problems from the start using as few tutorials as possible is much more beneficial.
  14. Does OP need 32bit fields for this application? Converting to 16bit using the Primitive SOP will dramatically decrease disk write. Just don't know if you need the precision for advection?
  15. @marty being that I can't even figure out how to get animation into FEM I doubt I'll be figuring this one out ... though I do have an idea. Point me in the right direction and I'll give it a try.