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Everything posted by pusat

  1. Simple VEX/Houdini array question

    You can also use len VEX function but both return integers.
  2. select one edge from group ?

    Edge groups are not as easy to work in Houdini as point/prim groups. You can do this using a Python SOP though: edge = geo.findEdgeGroup("edgegroup").edges()[0] newgroup = geo.createEdgeGroup("one") newgroup.add(edge)
  3. Smallest-circle problem to bound points?

    I made this operator when I first started using Houdini. It's from Dave Eberly's library: https://www.dropbox.com/s/ojzptmfpafqjw5n/MinimumCircle_SOP_Animatrix.otl?dl=1 Could be made faster by using least squares methods instead.
  4. Pyro Clustering Tutorial

    You can also do this without a For Loop block using a Volume Wrangle SOP.
  5. Houdini 17 Wishlist

    There are many other kitchen and sink nodes that need to be broken up: Facet SOP, Primitive SOP, Fuse SOP, etc.
  6. For Each Element in Group

    If you loop over the enum attribute, the -1 will only be 1 iteration and you can skip it by using a switch node so it's not costly to do so.
  7. For Each Element in Group

    Enumerate SOP can do this.
  8. Performs PCA (Principal Component Analysis) on a point cloud.
  9. It's the simplest method but not the fastest. If you want to perform this operation the fastest, you need to pre-generate your points using Point Generate SOP (nprims()) and then move each point to the center of each primitive using the second input as the reference. That way you avoid the geometry creation and deletion operations, both of which are very expensive. Creating points using Point Generate SOP is extremely fast, since it creates all points at the origin.
  10. Volume Deform SOP

    Straight VEX based volume deformation with no geometry conversion in between.
  11. Two minute papers

    I find that channel pretty useless. Just non-technical commentary on new papers.
  12. Indeed, this tool only creates connections between immediate neighbours up to N depth, so you don't need to create unnecessary connections. After that you can decide how to break up your glue network using noise, rules, etc. In your case you can easily identify the connections that belong to different material by querying the attributes as this node stores original name attributes, and which piece they originate from, etc.
  13. You can achieve it using something like this: Later on I made a more generic version called Adjacency Skeleton. Need to update the video sometime
  14. I think you need some kind of optical flow algorithm so you can certainly use PCA: https://ps.is.tue.mpg.de/research_projects/pca-flow https://github.com/jswulff/pcaflow https://asp-eurasipjournals.springeropen.com/articles/10.1155/2010/680623
  15. Houdini 17 Wishlist

    Before any new serious COP features though, SESI needs to fix some core bugs that are as old as the system itself. I reported many but I get the feeling that there are no plans to address any of them. There are threading issues, deadlocks, round trip (COP to SOP to COP) limitation, GPU image artifacts, anti-aliasing issues using the exact same code in VOPs vs VEX, etc. Otherwise I really like COPs too. I made an OpenCL Wrangle COP recently that proves to be very useful for image filters.
  16. You can make your own modeling tools. Check out some examples here: http://orbolt.com/search/?q=animatrix+sop
  17. Houdini 17 Wishlist

    +1, this is a nice RFE. I wrote shelf scripts that does this for Display flag so it's possible to script this action as well. I can send you the code if you want that you can bind to a hotkey. My RFE: In H16 if you copy some text inside Houdini such as code from inside an AttribWrangle and then select and copy a node tile, and then paste inside an AttribWrangle, Houdini will paste the path of the node inside the text editor. Before 16, it didn't do this, it preserved node tile copy clipboard separate from textual clipboard. If this is a new feature then it should have its own shortcut not alter the default copy/paste behaviour people have used to for a long time IMO. [ID# 84001]
  18. Randomize Carve Animation

    Compiling wouldn't work with Carve SOP as it's not compilable yet.
  19. It's very easy. First compute the best fit plane of these points. You can use this VEX tool: http://orbolt.com/asset/animatrix::bestFitPlane::1.00 Then create a circle in VEX that's at origin on XZ plane, then using: matrix3 m = dihedral ( {0,1,0}, bestFitPlaneNormal ); multiply your new circle points with m and then add bestFitPlaneCenter to these points.
  20. Volume Velocity to Mesh?

    You can use Attribute From Volume SOP.
  21. This operator allows you to run an OpenCL kernel as part of your COP network. Depending on the GPU, some operators can be orders of magnitude faster than even VEX. In this case OpenCL is 192 times faster than VEX on GTX 970. Please note that the actual cooking time for the VEX node is much longer (~77s for 100 iterations vs 40s for 10000 iterations) than what the status bar is showing. The cooking timer is shown long after I set iterations to 100 as can be seen in the video.
  22. Select Outside Edges Only

    There are many ways to do this but one way I would do is delete all groups but the largest one by element count using something like this: https://www.dropbox.com/s/lkl7j2w6r65r2im/DeleteGroupsByCount_SOP_Animatrix.otl?dl=1
  23. Projected caustics from water overhead

    You can fake it using point clouds: