Compute normal vectors of 2.5D triangulation 1.0

It could be useful to know the normal vectors of a surface. The function provided is able to take a 2.5D unrestricted triangulation (Delaunay or not) which define a 3D surface and computes the normal vectors of each cell. It is possible to compute vectors at the center cells or at vertices.Inputs : "XYZ" is the coordinate of the vertex of the triangulation (nx3 matrix). "TRI" is the list of triangles which contain indexes of XYZ (mx3 matrix). "strPosition" is the position where the normal is computed. It could be 'center-cells' for a computation on the center of each triangle or could be 'vertices' and the vectors are computed at vertices with respect to the neighbor cells (string).Outputs : "NormalVx", "NormalVy" and "NormalVz" are the component of normal vectors (normalized to 1). "PosVx", "PosVy" and "PosVz" is the positions of each vector. Note : if strPosition == 'center-cells', then the dimension of each output are mx1. if strPosition == 'vertices', then the dimension of each output are nx1. All cells have to be enumerated clockwise or counter-clock. Example : [X,Y,Z]=peaks(25); X=reshape(X,[],1); Y=reshape(Y,[],1); Z=0.4*reshape(Z,[],1); TRI = delaunay(X,Y); [NormalVx NormalVy NormalVz PosVx PosVy PosVz]=computeNormalVectorTriangulation([X Y Z],TRI,'vertices'); quiver3(PosVx,PosVy, PosVz, NormalVx, NormalVy, NormalVz), axis equal hold on trimesh(TRI,X,Y,Z) David Gingras, February 2009

Requirements:	No special requirements
Platforms:	Matlab
Keyword:	Clockwise,  Counterclock,  Dimension,  Enumerated,  Output,  Positions,  Quotposvyquot,  Quotposvzquot,  Strposition,  Vector
Users rating:	0/10