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About MoltenCrazy

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  1. Surface as force volume?

    Great example, Henry. I think I'm all set on the VDB approach. And it looks like I can use the approach on either static or deforming geo, which is fantastic. I'm curious about the the Field Force example you gave. I gave it a go based on your description but can't seem to make it work. I've tried referencing both the shatter geo and the interior geo in the SOP Geometry node, but in both cases the force attribute isn't coming in with the geo. Does this approach also require a SOP Solver node to wire up the points and forces? Metaball_Test_03a_FieldForce.hiplc
  2. Surface as force volume?

    In case it helps, this is a rough test of the metaball-based effect I'm hoping to replicate with the velocity volume. Metaball_Test_02.hiplc
  3. Surface as force volume?

    Thanks, toadstorm; this definitely helps. More and more impressed by the VDB functionality in Houdini. I'm still stuck on how to get the velocity to be fully recognized as a force in an RBD sim, though. With a FLIP solver it seems a bunch easier since there is an input for volumes on the solver. In an RBD DOPnet I'm bringing in the velocity with a SOP Vector Field and wiring it through a Field Force node. I have something happening, but the Field Force node only seems to work in a single direction; there's no sense of the velocity data from the surface/VDB 'normals'. volume_gradient_example_02.hiplc
  4. Surface as force volume?

    Hey, toadstorm...thanks for the response. Can you go into a little more detail? Are you suggesting I create a Volume Velocity node or a Volume Velocity From Surface node to create the initial volume? As for the point cloud functions, are you referring to something like pcfind in VEX, or a Point Cloud Iso node? And when you refer to 'binding' to the velocity volume, are you referring to using it as a mask? This is the first work I've done with volumes, so I'm not familiar with the approach. -- mC
  5. Is it possible to covert a surface into a form that defines a force volume? I have a character that will have pieces popping off it, basically a fracturing shell. I've (mostly) achieved the effect in tests with a sphere, randomly deleted glue constraints, and a metaball to provide the illusion the force is coming from under the surface itself. While I think I can mash together metaballs to get me the form I need, it would be better if I could just use the underlying surface as the repelling force volume, especially if the character is animated/deforming. Can this be done, either by using a surface directly as the volume or maybe as a force mask inside a larger metaball region? Thanks! -- mC
  6. Boolean Fracture Seams

    Hey, John! Thanks for the quick reply and...the solution! Pretty sure I had a bad node in my network, too...I modified my network in-place to match yours and still had seams. I completely rebuilt a new network beside it, and--boom--it worked, with the exception of the final Normal node. If I use it in my network, there are no seams at the Boolean node but they appear at the final Normals node. -- mC
  7. Boolean Fracture Seams

    Is there a way to fully eliminate seams in a model after a boolean shatter? I'm able to get rid of most of the seams with the boolean 'unique points along seams' flag and a Normals SOP, but in both Redshift and Mantra renders it's still clear that the surface has been shatter before a sim is applied. Any way around this? -- mC Boolean Seams - Sphere - 01.hiplc
  8. Shell fracture precision/interpenetration issues

    DoH! I was so focused on debugging the fracturing geo I didn't think about the collision geo! Thanks, Polyxion! Still new to a lot of this...do you think either the voronoifracture or the vdb approach (or both) would work with deforming/animated geo as well? Oh, and I'm about halfway through the recent videos by Jeff. Thanks for that as well. -- moltenCrazy
  9. Hi, all...need to do a shatter effect where the outer 'shell' of a static (for now) character/figure crumbles to reveal a different material/surface beneath. Been doing a lot of testing with a simple torus as it's a fair representation of the tubular topography of most of the figure (arms, legs, torso, etc). I feel I've finally got a good grasp on all the fracturing basics, but for the life of me I can't keep the outer shell fragments from interpenetrating with the underlying shell. I've tried: Increasing the DOP network substeps Increasing the rigid body solver substeps Switching the RBD packed object geo representation from Convex to Concave Altering the collision padding based on what it does to the guide geometry Increasing the number of fragments in connection with all of the above The changes either lead to little difference or in cases where I kick up the substeps and subsequently (I think) the precision, the fragments do the old-style 'exploding off the surface' thing. At this point, I have to wonder...in this situation should I just switch to the RBD solver? I'm okay getting hammered on sim time if I know it's going to work in the end. Oh, and a question about the collision padding...is that designed to pad the fragment intersection with other surfaces, each other, or both? Any help would be great. Really been banging my head against the wall on this one. -- moltenCrazy Shatter Tests - Torus - 02.hiplc
  10. Fracture shell 'popping' force

    Hey, all...I'm working on a test in which I want to have fractured shell pieces appear to 'pop' off the underlying surface as though the force came from the surface below. From my reading, it seems like the two most likely candidates are a field force or a point force. I'm guessing I'd want the force impulse to travel along the average normal of the outer shell piece...? Anyone done something similar? Am I on the right path with either the field force or the point force? My searches on this type of effect got a lot of noise...turns out the word 'POP' is pretty common here. Who knew? -- mC
  11. Random/Controlled Fracture Start Points

    Hey, all...I'm slamming my head against the wall on something that I thought would be common but I haven't been able to find an answer in any searches. In my Franken-file (cobbled together from multiple sources) I have a surface that crumbles with a Voronoi fracture to reveal another surface beneath it. The crumble effect happens without an impact; it's driven by wind and gravity. The core of it is working pretty well so far, except that I can only currently get the crumble to start from one location along an axis and continue in a linear fashion along said axis. This is done via an Attribute VOP node. What I need is to have the crumble start in multiple semi-random locations and proceed from each random start point. I'm fine picking the start points if there isn't a random/semi-random approach. I'd be grateful for any help; up against a deadline. Thanks!