在网上搜索这个题目可以找到一些类似的文章，其来源大致都是http://people.sc.fsu.edu/~jburkardt/m_src/ply_io/ply_io.html。但是并没有说明怎样运行和显示，因此我做这篇博客详细讲解一下。首先是这个ply_read.m文件

function [ Elements, varargout ] = PLY_READ ( Path, Str )

%*****************************************************************************80
%
%% PLY_READ reads a PLY 3D data file.
%
%   [DATA,COMMENTS] = PLY_READ(FILENAME) reads a version 1.0 PLY file
%   FILENAME and returns a structure DATA.  The fields in this structure
%   are defined by the PLY header; each element type is a field and each
%   element property is a subfield.  If the file contains any comments,
%   they are returned in a cell string array COMMENTS.
%
%   [TRI,PTS] = PLY_READ(FILENAME,‘tri‘) or
%   [TRI,PTS,DATA,COMMENTS] = PLY_READ(FILENAME,‘tri‘) converts vertex
%   and face data into triangular connectivity and vertex arrays.  The
%   mesh can then be displayed using the TRISURF command.
%
%   Note: This function is slow for large mesh files (+50K faces),
%   especially when reading data with list type properties.
%
%   Example:
%   [Tri,Pts] = PLY_READ(‘cow.ply‘,‘tri‘);
%   [Tri,Pts] = PLY_READ(‘bunny.ply‘,‘tri‘);
%   trisurf(Tri,Pts(:,1),Pts(:,2),Pts(:,3));
%   colormap(gray); axis equal;
%
%  Discussion:
%
%    The original version of this program had a mistake that meant it
%    did not properly triangulate files whose faces were not already triangular.
%    This has been corrected (JVB, 25 February 2007).
%
%    Glenn Ramsey pointed out and corrected a problem that occurred
%    with an uninitialized value of Type2, 27 August 2012.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    27 August 2012
%
%  Author:
%
%    Pascal Getreuer 2004
%
%  Parameters:
%
%  Local Parameters:
%
%    COMMENTS, any comments from the file.
%
%    ELEMENTCOUNT, the number of each type of element in file.
%
%    ELEMENTS, the element data.
%
%    PROPERTYTYPES, the element property types.
%
%    SIZEOF, size in bytes of each type.
%

%
%  Open the input file in "read text" mode.
%
  [ fid, Msg ] = fopen ( Path, ‘rt‘ );

  if ( fid == -1 )
    error ( Msg );
  end

  Buf = fscanf ( fid, ‘%s‘, 1 );

  if ( ~strcmp ( Buf, ‘ply‘ ) )
    fclose ( fid );
    error(‘Not a PLY file.‘);
  end
%
%  Read the header.
%
  Position = ftell(fid);
  Format = ‘‘;
  NumComments = 0;
  Comments = {};
  NumElements = 0;
  NumProperties = 0;
  Elements = [];
  ElementCount = [];
  PropertyTypes = [];
  ElementNames = {};  % list of element names in the order they are stored in the file
  PropertyNames = [];  % structure of lists of property names

  while ( 1 )
%
%  Read a line from the file.
%
    Buf = fgetl ( fid );
    BufRem = Buf;
    Token = {};
    Count = 0;
%
%  Split the line into tokens.
%
    while ( ~isempty(BufRem) )

      [ tmp, BufRem ] = strtok(BufRem);
%
%  Count the tokens.
%
      if ( ~isempty ( tmp ) )
        Count = Count + 1;
        Token{Count} = tmp;
      end

    end
%
%  Parse the line.
%
    if ( Count )

      switch lower ( Token{1} )
%
%  Read the data format.
%
      case ‘format‘

        if ( 2 <= Count )

          Format = lower ( Token{2} );

          if ( Count == 3 & ~strcmp ( Token{3}, ‘1.0‘ ) )
            fclose ( fid );
            error(‘Only PLY format version 1.0 supported.‘);
          end
        end
%
%  Read a comment.
%
      case ‘comment‘

        NumComments = NumComments + 1;
        Comments{NumComments} = ‘‘;
        for i = 2 : Count
          Comments{NumComments} = [Comments{NumComments},Token{i},‘ ‘];
        end
%
%  Read an element name.
%
      case ‘element‘

        if ( 3 <= Count )

          if ( isfield(Elements,Token{2}) )
            fclose ( fid );
            error([‘Duplicate element name, ‘‘‘,Token{2},‘‘‘.‘]);
          end

          NumElements = NumElements + 1;
          NumProperties = 0;
          Elements = setfield(Elements,Token{2},[]);
          PropertyTypes = setfield(PropertyTypes,Token{2},[]);
          ElementNames{NumElements} = Token{2};
          PropertyNames = setfield(PropertyNames,Token{2},{});
          CurElement = Token{2};
          ElementCount(NumElements) = str2double(Token{3});

          if ( isnan(ElementCount(NumElements)) )
            fclose ( fid );
            error([‘Bad element definition: ‘,Buf]);
          end

        else

          error([‘Bad element definition: ‘,Buf]);

        end
%
%  Read an element property.
%
      case ‘property‘

        if ( ~isempty(CurElement) & Count >= 3 )

          NumProperties = NumProperties + 1;
          eval([‘tmp=isfield(Elements.‘,CurElement,‘,Token{Count});‘],...
            ‘fclose(fid);error([‘‘Error reading property: ‘‘,Buf])‘);

          if ( tmp )
            error([‘Duplicate property name, ‘‘‘,CurElement,‘.‘,Token{2},‘‘‘.‘]);
          end
%
%  Add property subfield to Elements.
%
          eval([‘Elements.‘,CurElement,‘.‘,Token{Count},‘=[];‘], ...
            ‘fclose(fid);error([‘‘Error reading property: ‘‘,Buf])‘);
%
%  Add property subfield to PropertyTypes and save type.
%
          eval([‘PropertyTypes.‘,CurElement,‘.‘,Token{Count},‘={Token{2:Count-1}};‘], ...
            ‘fclose(fid);error([‘‘Error reading property: ‘‘,Buf])‘);
%
%  Record property name order.
%
          eval([‘PropertyNames.‘,CurElement,‘{NumProperties}=Token{Count};‘], ...
            ‘fclose(fid);error([‘‘Error reading property: ‘‘,Buf])‘);

         else

           fclose ( fid );

           if ( isempty(CurElement) )
             error([‘Property definition without element definition: ‘,Buf]);
           else
             error([‘Bad property definition: ‘,Buf]);
           end

         end
%
%  End of header.
%
        case ‘end_header‘
          break;

      end
    end
  end
%
%  Set reading for specified data format.
%
  if ( isempty ( Format ) )
    warning(‘Data format unspecified, assuming ASCII.‘);
    Format = ‘ascii‘;
  end

  switch Format

    case ‘ascii‘
      Format = 0;
    case ‘binary_little_endian‘
      Format = 1;
    case ‘binary_big_endian‘
      Format = 2;
    otherwise
      fclose ( fid );
      error([‘Data format ‘‘‘,Format,‘‘‘ not supported.‘]);

  end
%
%  Read the rest of the file as ASCII data...
%
  if ( ~Format )
    Buf = fscanf ( fid, ‘%f‘ );
    BufOff = 1;
  else
%
%  ...or, close the file, and reopen in "read binary" mode.
%
    fclose ( fid );
%
%  Reopen the binary file as LITTLE_ENDIAN or BIG_ENDIAN.
%
    if ( Format == 1 )
      fid = fopen ( Path, ‘r‘, ‘ieee-le.l64‘ );
    else
      fid = fopen ( Path, ‘r‘, ‘ieee-be.l64‘ );
    end
%
%  Find the end of the header again.
%  Using ftell on the old handle doesn‘t give the correct position.
%
    BufSize = 8192;
    Buf = [ blanks(10), char(fread(fid,BufSize,‘uchar‘)‘) ];
    i = [];
    tmp = -11;

    while ( isempty(i) )

      i = findstr(Buf,[‘end_header‘,13,10]);   % look for end_header + CR/LF
      i = [i,findstr(Buf,[‘end_header‘,10])];  % look for end_header + LF

      if ( isempty(i) )
        tmp = tmp + BufSize;
        Buf = [Buf(BufSize+1:BufSize+10),char(fread(fid,BufSize,‘uchar‘)‘)];
      end

    end
%
%  seek to just after the line feed
%
    fseek ( fid, i + tmp + 11 + (Buf(i + 10) == 13), -1 );

  end
%
%  Read element data.
%
%  PLY and MATLAB data types (for fread)
%
  PlyTypeNames = {‘char‘,‘uchar‘,‘short‘,‘ushort‘,‘int‘,‘uint‘,‘float‘,‘double‘, ...
    ‘char8‘,‘uchar8‘,‘short16‘,‘ushort16‘,‘int32‘,‘uint32‘,‘float32‘,‘double64‘};

  MatlabTypeNames = {‘schar‘,‘uchar‘,‘int16‘,‘uint16‘,‘int32‘,‘uint32‘,‘single‘,‘double‘};

  SizeOf = [1,1,2,2,4,4,4,8];

  for i = 1 : NumElements
%
%  get current element property information
%
    eval([‘CurPropertyNames=PropertyNames.‘,ElementNames{i},‘;‘]);
    eval([‘CurPropertyTypes=PropertyTypes.‘,ElementNames{i},‘;‘]);
    NumProperties = size(CurPropertyNames,2);

%   fprintf(‘Reading %s...\n‘,ElementNames{i});
%
%  Read ASCII data.
%
    if ( ~Format )

      for j = 1 : NumProperties

        Token = getfield(CurPropertyTypes,CurPropertyNames{j});

        if ( strcmpi(Token{1},‘list‘) )
          Type(j) = 1;
        else
          Type(j) = 0;
        end
%
%  Glenn Ramsey 20120827 
%  Initialise Type2{} to prevent uninitialised value error.
%
        Type2{j} = ‘‘;

      end
%
%  Parse the buffer.
%
      if ( ~any(Type) )

         % no list types

        Data = http://www.mamicode.com/reshape ( ...>输入的参数是两个，一个是ply文件的位置，另一个是打开方式，一般为‘tri‘
对于ply格式的解答这里有几篇文章可以参考：PLY文件格式剖析(一)，PLY文件格式剖析(二)
PLY_DISPLAY这个函数也是类似的
但是事实上用txt直接读取ply格式确是有可能出现乱码的
但是某些只有点和面的信息的格式是被允许的
例如下图的棱锥
ply
format ascii 1.0
comment created by MATLAB ply_write
element vertex 5
property float x
property float y
property float z
element face 6
property list uchar char vertex_indices
end_header
0.000000 0.000000 0.000000 
1.000000 0.000000 0.000000 
1.000000 1.000000 0.000000 
0.000000 1.000000 0.000000 
0.500000 0.500000 1.600000 
3 1 0 3 
3 1 3 2 
3 0 1 4 
3 0 4 3 
3 3 4 2 
3 1 2 4 

此外，更为复杂的cow可以在我的资源页处下载，下面就是读取ply格式的文件了，这里文中给定的例子略微有点问题，应该调用的是矩阵的转置
[Tri,Pts] = PLY_READ(‘coww.ply‘,‘tri‘);
Pts=Pts‘;
trisurf(Tri‘,Pts(:,1),Pts(:,2),Pts(:,3));
cow
MATLAB绘制效果
meshlab显示效果
但是对于一般的ply文件利用这个函数却不能正确读出Tri来。。可能他的代码还有待改善吧。。
MATLAB对ply文件格式的读取和显示