MESHFACENORMALS Compute normal vector of faces in a 3D mesh.

   NORMALS = meshFaceNormals(VERTICES, FACES)
   VERTICES is a set of 3D points (as a N-by-3 array), and FACES is either
   a N-by-3 index array or a cell array of indices. The function computes
   the normal vector of each face.
   The orientation of the normal is defined by the sign of cross product
   between vectors joining vertices 1 to 2 and 1 to 3.


   Example
     [v e f] = createIcosahedron;
     normals1 = meshFaceNormals(v, f);
     centros1 = meshFaceCentroids(v, f);
     figure; drawMesh(v, f); 
     hold on; axis equal; view(3);
     drawVector3d(centros1, normals1);

     pts = rand(50, 3);
     hull = minConvexHull(pts);
     normals2 = meshFaceNormals(pts, hull);

   See also
   meshes3d, meshFaceCentroids, meshVertexNormals, drawFaceNormals
   drawMesh 

Package: matgeom