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  1. Quaoar

    Commands list

    We now have the full commands list automatically grabbed from the Tcl interpreter and published nightly here:
  2. Quaoar

    How to realize the curvature comb function and what is the principle?

    I'm moving this question here from the bugtracker issue. For the implementation of curvature plots and combs, one can start off by reading the following paper: Farin, G. (2016). Curvature combs and curvature plots. Computer-Aided Design, 80, 6–8. In...
  3. Quaoar

    HNY 2022

    Hey everyone. Let me wish everybody who's ever posted any message here tons of success in the coming year. We've just started but I already learned a lot talking to you, guys. Hopefully, you share my excitement about our small community that has already proven to be an efficient "tool" of...
  4. Quaoar

    Upcoming release ver.1.2

    Here's the list of tickets planned for fixing: If there's anything you'd like to see in the next version, post here.
  5. Quaoar

    Let's discuss units

    One important topic to touch on is the measurement units. It's often the case that non-SI units are used, and we have to survive such cases. For example, inches are popular in US and UK and the CAD files from these geographic locations might require extra caution. Btw, a tool to consult units...
  6. Quaoar

    STEP features | How to communicate threads via a STEP file?

    I came across the following issue recently. A guy asks how a STEP file could help in the following scenario: The user uploads a STEP file. All drilled holes are recognized with some simple AFR approach. The user selects a couple of cylindrical bores and clicks some buttons to associate threads...
  7. Quaoar

    Community digest series

    I was thinking to summarize interesting topics that we have discussed during a certain period of time (say, one-three months). Here is the first digest: This topic is pinned, so I'll keep...
  8. Quaoar

    Build helix in OpenCascade

    I came across this thread in the official OCC forum, and could not resist the impulse to touch on that helix construction in OpenCascade: Let's discuss here how to build helical curves. I'll get back here soon with a piece of...
  9. Quaoar

    OpenCascade 7.6 is released

    Here is the news: Here is the corresponding FreeCAD forum topic: There are some neat features in this release that did not get much attention even in the official...
  10. Quaoar

    FOSDEM 2022

    Coming soon:
  11. Quaoar

    Slicing: looking for a non-convex hull algorithm

    Hey guys. I'm now working on the slicing problem (not for 3D printing) where I need to intersect a CAD model with a stack of planes. The process is quite simple and can be outlined as follows: 1. Switch from B-rep to meshes. 2. Intersect mesh edges with planes (1-dimensional intersection, fast...
  12. Quaoar

    Interfacing OpenCascade with NetGen

    This topic is kind of complementary to Refining Poly_Triangulation meshes as it appears that I underestimated (a lot!) the development efforts required to build up a decent refiner. Since I do not have any open budget to continue working on refinement techniques life-long, it seems it's the...
  13. Quaoar

    Release v1.1

    Analysis Situs ver.1.1 has seen the light of day. Read more on the blog.
  14. Quaoar

    BREP compatibility issue

    Regarding the BREP compatibility issue mentioned above, here're some additional details. People who are going to use OpenCascade 7.6 (to be released soon) should anticipate that the new BREP files (*.brep) won't open in the older versions of OpenCascade. Kirill (the architect of OpenCascade)...
  15. Quaoar

    Read STEP files with non-ASCII filename characters

    The data exchange interfaces of OpenCascade can work with Unicode characters in filenames if the UTF-8 codepage is used. That explains why all translators expose Standard_CString (const char*) as the input type: it's good enough for UTF-8. Here is how one can convert QString to UTF-8 string to...
  16. Quaoar

    Get entity names from a STEP file

    An interesting question was posted by one of our subscribers under Lesson 12: This thread is to elaborate a bit on this subject. I think I had a code snippet somewhere doing that thing, but I need to double-check it. Here's a related question from the "official" forum:
  17. Quaoar

    Fast point-face classifier (?)

    Here's another issue I came across, and I do not have any solution so far. What I'm doing is sampling CAD faces in their UV spaces with uniform grids. Something like that: And with the grid overlay: The red color means that the corresponding point falls inside the parametric domain of a...
  18. Quaoar


    I'm going to be off for 3 weeks or so, starting from 08.08. Here is the draft plan for the road trip (on map): Not sure if I'll manage to follow along with the forum in this period of time, so here is the excuse :)
  19. Quaoar

    Save to STEP with colored faces, edges or vertices

    Yesterday I got the question of how to colorize part's faces and save the colored part to STEP. Here's how one can do this using XDE/OCAF framework of OpenCascade: TopoDS_Shape partShape = // Your shape /* Create application and document of the XDE format */ Handle(TDocStd_Application)...
  20. Quaoar

    Refine Poly_Triangulation meshes

    Here in this topic, I'd like to accumulate some information on triangulation refinement in OpenCascade. As we all know, the meshes are stored in Poly_Triangulation data structures that are distributed by TopoDS_Face entities in the model. The standard open source mesher (BRepMesh) generates a...