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) or
   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) or
0018 %   not (TF=false). Default is false.
0019 %
0020 %   Example
0021 %     [v, f] = createSoccerBall;
0022 %     f = triangulateFaces(f);
0023 %     box = [0 2 -1 2 -.5 2];
0024 %     [v2, f2] = clipMeshVertices(v, f, box, 'inside', false);
0025 %     figure('color','w'); view(3); axis equal
0026 %     drawMesh(v, f, 'faceColor', 'none', 'faceAlpha', .2);
0027 %     drawBox3d(box)
0028 %     drawMesh(v2, f2, 'faceAlpha', .7);
0029 %
0030 %   See also
0031 %   meshes3d, clipPoints3d
0032 %
0033 
0034 % ------
0035 % Author: David Legland, oqilipo
0036 % E-mail: david.legland@inrae.fr
0037 % Created: 2011-04-07, using Matlab 7.9.0.529 (R2009b)
0038 % Copyright 2011-2024 INRA - Cepia Software Platform
0039 
0040 % if input is given as a structure, parse fields
0041 if isstruct(v)
0042     if nargin > 2
0043         varargin = [b, varargin]; 
0044     end
0045     b = f;
0046     f = v.faces;
0047     v = v.vertices;
0048 end
0049 
0050 parser = inputParser;
0051 validStrings = {'box', 'sphere', 'plane'};
0052 addParameter(parser, 'shape', 'box', @(x) any(validatestring(x, validStrings)));
0053 addParameter(parser, 'inside', true, @islogical);
0054 addParameter(parser, 'trimMesh', false, @islogical);
0055 parse(parser, varargin{:});
0056 
0057 % clip the vertices
0058 [v2, indVertices] = clipPoints3d(v, b,...
0059     'shape', parser.Results.shape, 'inside', parser.Results.inside);
0060 
0061 % create index array for face indices relabeling
0062 refInds = zeros(size(indVertices));
0063 for i = 1:length(indVertices)
0064     refInds(indVertices(i)) = i;
0065 end
0066 
0067 % select the faces with all vertices within the box
0068 if isnumeric(f)
0069     % Faces given as numeric array
0070     indFaces = sum(~ismember(f, indVertices), 2) == 0;
0071     f2 = refInds(f(indFaces, :));
0072     
0073 elseif iscell(f)
0074     % Faces given as cell array
0075     nFaces = length(f);
0076     indFaces = false(nFaces, 1);
0077     for i = 1:nFaces
0078         indFaces(i) = sum(~ismember(f{i}, indVertices), 2) == 0;
0079     end
0080     f2 = f(indFaces, :);
0081     
0082     % re-label indices of face vertices (keeping horizontal index array)
0083     for i = 1:length(f2)
0084         f2{i} = refInds(f2{i})';
0085     end
0086 end
0087 
0088 if parser.Results.trimMesh
0089     [v2, f2] = trimMesh(v2, f2);
0090 end
0091 
0092 varargout = formatMeshOutput(nargout, v2, f2);