Community digest series #01

  1. OpenCascade 7.6 is released with (?) kinematics.
  2. Here is how to plug in the NetGen mesher to your OpenCascade-based app.
  3. Fast point-face classifier.
  4. A simple slicing algorithm.

Arrow glyphs in AIS

OpenCascade is known to contain its in-house visualization framework named AIS (Application Interactive Services). We are lucky to have Natalia who is excited enough with this framework to share her experience and pieces of advice that are impossible to get otherwise. If you wanna customize AIS for visualizing oriented glyphs, here’s the topic to read.

Arrow glyphs in AIS.

OpenCascade in Python

Prototyping with OpenCascade was supposed to be driven by the Tcl console named Draw Test Harness. At the same time, it has never actually worked that way for the community. Non-programmers prefer using Python, like it or not. Personally, I do not use Python a lot, but I can definitely appreciate the simplicity of this whole Python business and how much you can get from it without investing days and weeks of work. Read this topic if you want to get started with PythonOCC.

PythonOCC with the hello-worldy box.

Constrained filling

The constrained filling remains a largely unresolved problem in OpenCascade. Still, there are tools that might be of some help. One of such is the Plate algorithm: a pinnacle of scientific research conducted in Matra/Cisigraph back in the glory days of the library. Jojain translated the technical spec for the Plate algorithm which helps us better understand the principles behind this computation.

Open-sourced Plate is being demystified.

Geometric constraint solver

Geometric constraint solvers are primarily used to solve sketches, i.e., satisfy all the constraints imposed by the user. In OpenCascade, such solvers do not exist. For example, to develop the SHAPER module of Salome, OCC borrowed the PlaneGCS solver from FreeCAD. Adam shared the Python code that is used for sketch solving in CadQuery. He used NLopt to solve the optimization problem.

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