Compute mesh normals

Calculate the normal vectors for each facet of a triangular mesh.

Compute mesh normals
====================

Adam H. Aitkenhead
[e-mail]
The Christie NHS Foundation Trust
1st December 2010

Calculate the normal vectors for each facet of a triangular mesh. The ordering of the vertices (clockwise/anticlockwise) is also checked for all facets if this is requested as one of the outputs.


USAGE:
======

[coordNORMALS] = COMPUTE_mesh_normals(meshdataIN);
..or..
[coordNORMALS,meshdataOUT] = COMPUTE_mesh_normals(meshdataIN);


INPUT PARAMETERS
================

meshdataIN - structure
Structure containing the faces and vertices of the mesh, in the same format as that produced by the isosurface command.

..or..

meshdataIN - Nx3x3 array
The vertex coordinates for each facet, with:
- 1 row for each facet
- 3 columns for the x,y,z coordinates
- 3 pages for the three vertices


OUTPUT PARAMETERS
=================

coordNORMALS - Nx3 array
The normal vectors for each facet, with:
- 1 row for each facet
- 3 columns for the x,y,z components

meshdataOUT - (optional)
The mesh data with the ordering of the vertices (clockwise/anticlockwise) checked. Uses the same format as <meshdataIN>.


EXAMPLES
========

To run an example of the code:

>> EXAMPLE_mesh_normals


NOTES
=====

- Computing <meshdataOUT> to check the ordering of the vertices in each facet may be slow for large meshes.
- Also, it may not be possible to compute <meshdataOUT> for non-manifold meshes.