Thanks for the additional details.
I cannot highlight elements (e.g., points, edges) when hovering with the mouse…
As I mentioned previously, Rhino does not have native mouse-over highlighting. Thus anything you do will be custom. Without giving this much thought, you’ll probably need a derived
CRhinoGetPoint object and perhaps a custom conduit as well.
For example, the
ExtractSubCrv kinda has mouse over highlighting. This is done by using a
CRhinoGetPoint object that is constrained to a curve. In the
OnMouseMove override, the closest segment to the active mouse location is detected and the segment is highlighted.
This kind of approach might work, depending on what you want to light up when you move the mouse.
I cannot have occlusion of elements…
Rhino will pick what it can see. Thus, if you are working in wireframe, then yes you can end up picking more mesh vertices than you want (by window selecting).
Custom objects, however, can provide their own picking code by overriding
CRhinoObject::Pick. Picking code can be complicated, so you will want to leverage the base class if you can.
I was wondering, how difficult could it be to implement them in my own plugin?
Unfortunately I am not familiar enough with T-Splines to be respond to this. I do know it is written in C++, which (hopefully) is encouraging to you.