3 ms·

Are you sure about OpenSCAD? I thought it used constructive solid geometry?

• jononor 7y ago
  Kinda, but I primarily have a user perspective. For instance even though most of the OpenSCAD language operators are classic CSG ones, there are variables to specify the number of facets on circles etc (which does not make much sense in a pure solids world). This can be controlled globally using the $fa/$fs/$fn variable (assuming a well-behaved model). Changing these variable seems to require the entire geometry to be rebuilt. Rebuilding the model itself is slow, and it gets slower the more facets you have - indicating that this is not just a 'display' feature. I believe this is because the underlying geometry kernel, CGAL, operates on meshes. Note that OpenSCAD can also export a CSG datastructure of a model. The OpenSCAD module in FreeCAD module uses this generate B-rep based solid models using their OpenCascade kernel. This raises the point of difference between OpenSCAD and Blender. In OpenSCAD the mesh is mostly a secondary thing, an artifact of how the internals are implemented - the "primary" model the user modifies is the code itself. Where as in Blender, the mesh is the primary model being modified by user. Although the distinction is a bit blurred, as Blender has some support for NURBS these days. And one can have non-destructive operators ("modifiers") such as subdivide/array/mirror etc.