The polyline is a nice object because it allows you to draw lot of lines with one render call.
Since GeeXLab version 0.9+, a Direct3D 12 renderer plugin is available in the Windows versions (32 and 64-bit).
On the Raspberry Pi there is a very nice feature that allows to create very cool shaped windows: the control of the opacity of the 3D window.
In recent versions of GeeXLab, I added the support of reflections (mirror, surface water for example). Here is how to do a reflection with GeeXLab: