clipMeshVertices

CLIPMESHVERTICES Clip vertices of a surfacic mesh and remove outer faces.

   [V2, F2] = clipMeshVertices(V, F, B)
   Clip a mesh represented by vertex array V and face array F, with the
   box represented by B. The result is the set of vertices contained in
   the box, and a new set of faces corresponding to original faces with
   all vertices within the box.
   
   [V2, F2] = clipMeshVertices(..., 'shape', 'sphere') Specify the shape.
   Default is 'box'. But it is also possible to use 'sphere' or 'plane'.
   
   [V2, F2] = clipMeshVertices(..., 'inside', false) removes the inner 
   faces instead of the outer faces.

   [V2, F2] = clipMeshVertices(..., 'trimMesh', TF)
   Also specifies if the isolated vertices need to be removed (TF=true) ot
   not (TF=false). Default is false.


   Example
     [v, f] = createSoccerBall;
     f = triangulateFaces(f);
     box = [0 2 -1 2 -.5 2];
     [v2, f2] = clipMeshVertices(v, f, box, 'inside', false);
     figure('color','w'); view(3); axis equal
     drawMesh(v, f, 'faceColor', 'none', 'faceAlpha', .2);
     drawBox3d(box)
     drawMesh(v2, f2, 'faceAlpha', .7);

   See also
   meshes3d, clipPoints3d

0001 function varargout = clipMeshVertices(v, f, b, varargin)
0002 %CLIPMESHVERTICES Clip vertices of a surfacic mesh and remove outer faces.
0003 %
0004 %   [V2, F2] = clipMeshVertices(V, F, B)
0005 %   Clip a mesh represented by vertex array V and face array F, with the
0006 %   box represented by B. The result is the set of vertices contained in
0007 %   the box, and a new set of faces corresponding to original faces with
0008 %   all vertices within the box.
0009 %
0010 %   [V2, F2] = clipMeshVertices(..., 'shape', 'sphere') Specify the shape.
0011 %   Default is 'box'. But it is also possible to use 'sphere' or 'plane'.
0012 %
0013 %   [V2, F2] = clipMeshVertices(..., 'inside', false) removes the inner
0014 %   faces instead of the outer faces.
0015 %
0016 %   [V2, F2] = clipMeshVertices(..., 'trimMesh', TF)
0017 %   Also specifies if the isolated vertices need to be removed (TF=true) ot
0018 %   not (TF=false). Default is false.
0019 %
0020 %
0021 %   Example
0022 %     [v, f] = createSoccerBall;
0023 %     f = triangulateFaces(f);
0024 %     box = [0 2 -1 2 -.5 2];
0025 %     [v2, f2] = clipMeshVertices(v, f, box, 'inside', false);
0026 %     figure('color','w'); view(3); axis equal
0027 %     drawMesh(v, f, 'faceColor', 'none', 'faceAlpha', .2);
0028 %     drawBox3d(box)
0029 %     drawMesh(v2, f2, 'faceAlpha', .7);
0030 %
0031 %   See also
0032 %   meshes3d, clipPoints3d
0033 %
0034 
0035 % ------
0036 % Author: David Legland, oqilipo
0037 % e-mail: david.legland@inra.fr
0038 % Created: 2011-04-07,    using Matlab 7.9.0.529 (R2009b)
0039 % Copyright 2011 INRA - Cepia Software Platform.
0040 
0041 % if input is given as a structure, parse fields
0042 if isstruct(v)
0043     if nargin > 2
0044         varargin = [b, varargin]; 
0045     end
0046     b = f;
0047     f = v.faces;
0048     v = v.vertices;
0049 end
0050 
0051 parser = inputParser;
0052 validStrings = {'box', 'sphere', 'plane'};
0053 addParameter(parser, 'shape', 'box', @(x) any(validatestring(x, validStrings)));
0054 addParameter(parser, 'inside', true, @islogical);
0055 addParameter(parser, 'trimMesh', false, @islogical);
0056 parse(parser, varargin{:});
0057 
0058 % clip the vertices
0059 [v2, indVertices] = clipPoints3d(v, b,...
0060     'shape', parser.Results.shape, 'inside', parser.Results.inside);
0061 
0062 % create index array for face indices relabeling
0063 refInds = zeros(size(indVertices));
0064 for i = 1:length(indVertices)
0065     refInds(indVertices(i)) = i;
0066 end
0067 
0068 % select the faces with all vertices within the box
0069 if isnumeric(f)
0070     % Faces given as numeric array
0071     indFaces = sum(~ismember(f, indVertices), 2) == 0;
0072     f2 = refInds(f(indFaces, :));
0073     
0074 elseif iscell(f)
0075     % Faces given as cell array
0076     nFaces = length(f);
0077     indFaces = false(nFaces, 1);
0078     for i = 1:nFaces
0079         indFaces(i) = sum(~ismember(f{i}, indVertices), 2) == 0;
0080     end
0081     f2 = f(indFaces, :);
0082     
0083     % re-label indices of face vertices (keeping horizontal index array)
0084     for i = 1:length(f2)
0085         f2{i} = refInds(f2{i})';
0086     end
0087 end
0088 
0089 if parser.Results.trimMesh
0090     [v2, f2] = trimMesh(v2, f2);
0091 end
0092 
0093 varargout = formatMeshOutput(nargout, v2, f2);