DGtal-team/DGtal — pull request #802 by dcoeurjo (2014-04-14 19:07:47+00:00)
Title: Adds methods to display surfels/quad with normal vectors

- Ok for both Viewer3D and Board3D.
- usage should be similar to

Display3DFactory<>::drawSurfelWithNormal(viewer,
surfel,
normalVector);

- at this point, surfel is an unsigned Khalimsky cell (WIP for signed one)

Illustration with a 100^3 digital sphere surface with "exact" normal vectors:

![snapshot](https://cloud.githubusercontent.com/assets/700165/2699552/eaf735d2-c407-11e3-91b5-b3b111ce92b3.jpg)

TODO:
- assert that the kcell/cell is a 2-cell