[Edit] this is an incomplete list of available geometry types. See
Geometry topic for more up to date information.
Hi
Here is a brief overview of geometry types:
BRep are the
BSpline Brep objects based on the Opencascade technology. They are imported/exported via step and iges. It is the main stream for parametric solid/surface modelling. They are great for everything, apart from the fact they are not that simple to modify programmatically. See the Modeling Curves and Shape explorer samples. They can be created at runtime in the program.
The next most useful section is the Mesh geometry. It is basically a mesh. It is imported from stl, vrml ad often from AutoCAD formats. It also can be built programmatically. They are very flexible to model anything, but its modification is not very simple as it is almost a raw set of points. There are operations for scaling, trimming, Boolean operations. Also, they can be changed in any way programmatically.
The problem here is that they are not parametric, so they are not built from curves and patches. So you need to know in the program where to move those points. Most often Mesh sections are generated or imported and if any modification is needed they are discarded and new one is created with from different parameters.
The native 3DS section was the first type of object KernelCAD was introduced with. It is useful in some cases, but is little unorthodox. 3DS were created as a simpler alternative in parametric modelling. 3DS are modelled with arc and straight line splines.
For simple case you need to define two or three cross-sections as closed arc/staright line curves to construct a 3DS. The burr model on the DInsight home page is a 3DS. One interesting feature of them is that they can be modelled in cylindrical coordinates using angle and distance to axis. It is useful for modelling spirals or similar axial (the burr) objects
SOR (surface if revolution) is a rotation of an arc/segment spline around z axis. They are pretty simple.