drawFaceNormals

DRAWFACENORMALS Draw normal vector of each face in a mesh.

   drawFaceNormals(V, E, F)
   Compute and draw the face normals of the mesh defined by vertices V,
   edges E and faces F. See meshes3d for format of each argument.

   H = drawFaceNormals(...)
   Return handle array to the created objects.

   Example
   % draw face normals of a cube
     [v, f] = createCubeOctahedron;
     figure; drawMesh(v, f)
     axis([-2 2 -2 2 -2 2]); axis equal; hold on;
     drawFaceNormals(v, f)
     view(3);

   See also
   meshes3d, drawMesh, drawVector3d, meshFaceNormals, meshFaceCentroids

0001 function varargout = drawFaceNormals(varargin)
0002 %DRAWFACENORMALS Draw normal vector of each face in a mesh.
0003 %
0004 %   drawFaceNormals(V, E, F)
0005 %   Compute and draw the face normals of the mesh defined by vertices V,
0006 %   edges E and faces F. See meshes3d for format of each argument.
0007 %
0008 %   H = drawFaceNormals(...)
0009 %   Return handle array to the created objects.
0010 %
0011 %   Example
0012 %   % draw face normals of a cube
0013 %     [v, f] = createCubeOctahedron;
0014 %     figure; drawMesh(v, f)
0015 %     axis([-2 2 -2 2 -2 2]); axis equal; hold on;
0016 %     drawFaceNormals(v, f)
0017 %     view(3);
0018 %
0019 %   See also
0020 %   meshes3d, drawMesh, drawVector3d, meshFaceNormals, meshFaceCentroids
0021 %
0022 
0023 % ------
0024 % Author: David Legland
0025 % e-mail: david.legland@inra.fr
0026 % Created: 2010-10-06,    using Matlab 7.9.0.529 (R2009b)
0027 % Copyright 2010 INRA - Cepia Software Platform.
0028 
0029 % extract vertices and faces
0030 mesh = parseMeshData(varargin{:});
0031 
0032 % compute vector data
0033 c = meshFaceCentroids(mesh);
0034 n = meshFaceNormals(mesh);
0035 
0036 % display an arrow for each normal
0037 h = quiver3(c(:,1), c(:,2), c(:,3), n(:,1), n(:,2), n(:,3));
0038 
0039 % format output
0040 if nargout > 0
0041     varargout{1} = h;
0042 end