Add line segments (vectors) to Q3DSurface charts
I've started using the Qt Datavisualization library to produce surface plots. I've used the "surface" example as a starting point. Rendering several surfaces goes fine. Now I want to use line segments to demonstrate the relation between different surfaces. I have looked at addCustomItem(), but this does not seem suitable, as it wants to add a 'fixed' object to the chart. This is also shown in the "Custom Items" example. What I need is a bit different. Think of the following examples :
at each mesh point of a (QSurface3DSeries) surface show a normal vector, who's length is proportional to local curvature.
from a (light) source location draw a line normal to a (QSurface3DSeries) surface, through the plane, till it ends up at its mirror location.
I'm not sure how to go about, all the OpenGl rendering done in the background is not (publicly) accessible through the Q3DSurface class.
Any advice would be much appreciated.