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Everything posted by jamesr

  1. Particles opacity control

    Here you go. It's made in 16.5 though, and I just saw above that you're in h15 for some reason... Let me know if you need it rebuild in h15 alpha_example.hiplc
  2. Cliff edge crumbling under weight of drifting car

    You should be able to get what you're looking for with a combination of Attribute Transfer/Sop solver to activate your pieces based on where the wheels are skidding, and the detailed boolean sim setup from the Applied Houdini Rigids IV (though I haven't watched it, so I'm not sure if you can use *exactly* the same methods and stuff). You can import the animation of your car, isolate the wheels of your vehicle, give them a red color and give your ground a black color. Fracture the ground/cliff area. As the wheels skid across the ground, they leave the red behind, and everything with a red value > some threshold will receive an "f@active" attribute value of 1. In the RBD sim, those pieces will then respond to forces and such, and you can have a gravity force and/or some custom point velocities to throw the pieces around in a fun way. Or you could use constraints (glue, or better yet cone-twist might look cooler since it will allow for some flexing and twisting before the pieces break away fully) to keep the pieces held together, and as the car skids over, the constraints start to weaken and break, causing them to crumble down. Here's a few links that might help: CG Wiki:: Houdini DOPs - A little over half way down the page has some RBD stuff, and different ways of activating them. CG Wiki:: Solver SOP - Everything on this page is important. CG Wiki:: Attribute Transfer - These examples show how transferring attributes work. Deleting glue constraints with color The Applied Houdini rigids I & II should give a good foundation, and I know in IV he does some cool stuff with the boolean sop which looks pretty nice. I hope the rough description helps a bit as I can't post a hip at the moment. Those links should help, and I'll try to throw something together when I get home if there's time. It helps to have a general direction to follow, since the scope of houdini can be quite large.
  3. Particles opacity control

    change the point attribute f@Alpha Make sure the 'A' is capitalized like that
  4. It's weird, because I have noticed what you're saying with snapping not working, or new nodes budging old aligned nodes out of place off-grid, but it also happens occasionally when opening a scene again, or opening a new network editor. I'll submit an RFE, too.
  5. Hey guys, Lately I've been using the grid in my network pane (tools > show grid), and I always snap my nodes to the intersection points so it's all nice and pretty. But every so often, multiple times a day, and usually when I re-open a scene, all the nodes will be nudged off, maybe ~1/4 grid space in a given direction. It's as if the grid is being drawn in a slightly different location. Obviously it's not a huge deal to just select all the nodes and scoot them over, but it gets a little redundant having to do it in every network, and kind of defeats the purpose of having a neat grid. I'm wondering if anyone else notices this or knows of an RFE for it, or if it's just me... Thanks!
  6. Flower growth

    Here's a great post from tomas slancik (anim) on the topic of copying and offsetting animation time. This might help get you started on that part. and here's one of the methods applied to your scene FLOWER_v002.hip
  7. Flip Collision

    It's hard to tell what's going on here. Could you post a hipfile? You should also check out the FLIP webinars by Jeff Wagner. A lot of FLIP questions can be answered there.
  8. Maximise Pscale

    I was thinking step size too, but even with it very low and iterations very high it never seemed to go away. And yeah I think you're right, I think it must be iterated and validated, but I'm pretty sure it could be done in a for loop in a vex wrangle outside of the sop solver as well.
  9. Flip Fluid Surface Problem

    Can you post a hip file?
  10. Maximise Pscale

    Hi! Here's what I came up with. There's still a tiny bit of overlap I can't seem to resolve, and I think I you can do it in a regular wrangle outside of a sop solver, but I haven't stuck it there yet. Anyways, here's what I got so far. ClosestDistanceTest_mk_v005.hip
  11. Any way to take non-planar volume slice?

    No problem, any time!
  12. Any way to take non-planar volume slice?

    Here's an example scene for you: mountain_volume_slice.hip
  13. Hi, If you want to rebuild the shaders in mat, instead of dropping down a Shopnet, drop down a Material Network. Then inside, put a Material Builder. You should then be able to replicate the shader from there. Any attributes you want to use can be brought in with a Bind VOP, and any parameters you want to link can be linked with Copy Parameter and Paste Relative References
  14. Krakatoa type effect with POP in Mantra

    f@pscale. Go really small with it, like 0.001. This is measured in world units (meters). See this thread for more info
  15. Realflow user - Flip questions

    Hi there! Flip works great the with "deforming object" shelf tool for collisions. When working with formats like alembic, you'll see that it comes in packed, and represented as a single point per object. You basically need to convert/unpack that geo for houdini to recognize all the geometry inside, and manipulate it like it would its native stuff. Getting into FLIP, definitely take a couple hours and watch these:
  16. If you have two boxes plugged into a merge node, you can select the box you want in the network editor, then hit "enter" in the viewport to get the handles for that box.
  17. krakatoa style rendering

    A lot of the look comes from the sheer amount of tiny particles. Krakatoa uses a concept they call partitioning to render particles over and over again with slightly different positions. You can do the same in houdini with wedging by randomly varying a seed value in your particle sim for each time the wedge is run. This lets you design one sim, then run a bunch of wedges (like partitions in krakatoa) instead of directly simulating potentially millions and millions of particles all in one go. If you want more detail, simply add more wedges! You can then load all the wedges at rendertime and get a very similar result. A couple of things that can help push the look are both tweaking the Alpha attribute of your particles, and adding a volume around it to help fill in the space.
  18. Oh ok! You should be able to head to your group sop, and on the very far right of the "Base Group" parameter there's an arrow pointing up. Click it, then shift+select the new points the viewport and hit enter.
  19. Do you mean add points to a group selection like in the group parameter of a node where you can isolate the effect of the node to just those points? Or are you actually creating a group and need to add points to it?
  20. Clean Growth PolyWires, Tutorials?

    Here you go: Curl Noise Flow - Entagma
  21. houdini alembic to maya problem

    Which renderer are you using?
  22. workflow for flip fluid sim/mesh/render

    Yup! They've got some example scene files you can download, too.
  23. Ramping into a group in POPS

    Try using a fit() function to remap the age, then scale the force itself by that. Should be possible in the VEXPression section of your POP Force. You don't even need to put the particles in a group (unless you want to). float newage = fit(@age, 1.5, 3, 0,10); force *= newage; This will ramp the force from 0 - 10 as the particle goes from age 1.5 - 3. Before that, the force is 0. Same can be done with "amp" in the noise section.
  24. You could copy/paste it into an empty houdini scene, then open that and copy/paste. Or simpler you just make the shop into an HDA and save it someplace and load it in.