Matlab 如何将.wrl（VRML）文件中的形状和纹理顶点提取到.mat

我有3D数据。其中有一个.wrlVRML文件。我需要加载该文件，然后仅提取形状和纹理顶点x、y、Z点。怎么做

这是我的代码：

%/*********************************************************************************
% FUNCTION NAME : read_vrml
% AUTHOR        : G. Akroyd
% PURPOSE  : reads a VRML or Inventor file and stores data points and connectivity
%             in arrays ready for drawing wireframe images.
%
% VARIABLES/PARAMETERS: 
%  i/p  filename       name of vrml file 
%  o/p  nel            number of geometry parts (elements) in file
%  o/p  w3d            geometry structure ;-
%                       w3d.pts   array of x y z values for each element                      
%                       w3d.knx   array of connection nodes for each element
%                       w3d.color color of each element
%                       w3d.polynum number of polygons for each element
%                       w3d.trans  transparency of each element
%
% Version / Date : 3.0   / 23-9-02
%                  removed triang optn & replaced face array Nan padding
%                   with 1st value padding to correct opengl display prob.
% Version / Date : 2.0   / 17-7-00
%                  changed output to a structure rather than separate arrays
%                   to use less memory.
%                  1.0   / 21-6-99
%                  original version
%**********************************************************************************/

function [nel,w3d,infoline] = read_vrml(filename)

keynames=char('Coordinate3','point','coordIndex');

  fp = fopen(filename,'r');
  if fp == -1
  fclose all;
  str = sprintf('Cannot open file %s \n',filename);
  errordlg(str);
  error(str);
  end

%* initialise arrays & counters */
  fv = zeros(1,3);
  foundkey=zeros(1,3); %* flags to determine if keywords found */
  endpts=0; %/* flag set when end of co-ord pts reached for an element */
  npt=0; %/* counter for num pts or conections */
  npol=1; % counter for number of polygons in an element
  nel=1; %/* counter for num of elements */
  color(1,1:3) = [0.5 0.55 0.5]; % default color
  maxnp = 0;
  tempstr = ' ';
  lastel = 1;
  lnum = 1;
  w3d(1).name = 'patch1';
  infoline = '#';
  trnsp(1) = 1; % transparency array - one val per element

  %/* start of main loop for reading file line by line */
  while ( tempstr ~= -1)
     tempstr = fgets(fp); % -1 if eof 
     if tempstr(1) == '#' & lnum == 2,
        infoline = tempstr;
     end 
     lnum = lnum +1; % line counter
     if ~isempty(findstr(tempstr,'DEF')) & ~endpts,
        w3d(nel).name = sscanf(tempstr,'%*s %s %*s %*s');
     end

     if ~isempty(findstr(tempstr,'rgb')) | ~isempty(findstr(tempstr,'diffuseColor')) % get color data 
     sp = findstr(tempstr,'[');
     if isempty(sp), sp = 12 + findstr(tempstr,'diffuseColor'); end
     nc = 0;
     if ~isempty(sp)
        sp = sp +1;                          
        [cvals,nc]=sscanf(tempstr(sp:length(tempstr)),'%f %f %f,');
     end
     if nc >= 3
        if nel > lastel+1 
           for m = lastel+1:nel-1
              color(m,1:3) = color(1,1:3); % if color not set then make equal to 1st 
           end 
        end 
        % if multi colors set then populate color matrix, this is an inventor feature
        for s = 1:fix(nc/3) 
              color(s+nel-1,1:3) = cvals(3*s-2:3*s)'; 
           lastel = s+nel-1;
        end    
     end 
 end 
 if ~isempty(findstr(tempstr,'transparency')), % get transparency level
     sp = findstr(tempstr,'trans');
     [tvals,nc]=sscanf(tempstr(sp+12:length(tempstr)),'%f');
     if nc > 0, trnsp(nel) = tvals(1); end
 end 

 for i=1:3  %/* check for each keyword in line */
    key = deblank(keynames(i,:));
    if ~isempty(findstr(tempstr,key)) & isempty(findstr(tempstr,'#')) 
       %/* if key found again before all found there is a problem
       %  so reset flag for that key */
       if ~foundkey(i), foundkey(i)=1;else foundkey(i)=0; end
       if(i>1 & ~foundkey(i-1)) foundkey(i)=0; end %/* previous key must exist first ! */
    end
 end
 if(foundkey(1) & foundkey(2)) %/* start of if A  first 2 keys found */
     if foundkey(3) %/* scan for connectivity data */
        tempstr = [tempstr,' #']; %/* last word marker for end of line */
        skip = '';
        %/* loop puts integer values in a line into connection array */
        word = ' ';
        while(word(1) ~= '#')
           format = sprintf('%s %%s#',skip);
           [word,nw] = sscanf(tempstr,format);
           skip = [skip,'%*s'];
           [node,nred] = sscanf(word,'%d,');
           if nred>0 
              for p = 1:nred
                 if node(p) ~= -1 
                    npt = npt +1; 
                    % increment node value as matlab counts from 1, vrml 0
                    w3d(nel).knx(npol,npt) = node(p)+1;
                 else
                    if npt > maxnp(nel), maxnp(nel) = npt; end 
                    npt = 0;
                    npol = npol + 1; 
                 end
              end
           end              
        end

        if ~isempty(findstr(tempstr,']')) %/* End of data block marker */
           polynum(nel)=npol-1; %/* store num of polygons in this element */
           endpts=0; %/* reset flag ready for next element search */
           npt=0;
           npol=1;
           foundkey = zeros(1,4); %/* reset keyword flags for next search */
           nel = nel+1; %/* now looking for next element so increment counter 
           maxnp(nel) = 0;
           w3d(nel).name = sprintf('patch%d',nel); % name next block
        end
     end %/* end of scan for connectivity */

     %/* got 1st 2 keys but not 3rd and not end of co-ords data */
     if(foundkey(2) & ~foundkey(3) & ~endpts) %/* scan for pts data */
        sp = findstr(tempstr,'[');
        if isempty(sp)
           %/* points data in x y z columns */
           [fv,nv]=sscanf(tempstr,'%f %f %f,');
        else
           %/* if block start marker [ in line - need to skip over it to data 
           %   hence pointer to marker incremented */
           sp = sp +1;
           [fv,nv]=sscanf(tempstr(sp:length(tempstr)),'%f %f %f,');
        end
        if(nv>0)
           if mod(nv,3) ~= 0
              fclose(fp);
              error('Error reading 3d wire co-ordinates: should be x y z, on each line');
           end 
           nov = fix(nv/3);
           for p = 1:nov
              npt = npt+1;
              w3d(nel).pts(npt,1:3)=fv(3*p-2:3*p); 
           end
        end                  
        if ~isempty(findstr(tempstr,']')) %/* end of pts data block */
           endpts=1; %/* flag to stop entry to pts scan while reading connections */
           npt=0;
        end
     end %/* end of scan for data pts */
 end %/* end of if A */     
end %/* end of main loop */

if nel == 0
    fclose(fp);
    error('Error reading 3d file: no data found');
end
nel = nel -1; 

% if not same number of verticies in each polygon we need to fill
% out rest of row in array with 1st value
nc = size(color); 
ts = size(trnsp);

for i = 1:nel 
facs = w3d(i).knx;
ind1 = find(facs==0); [rown,coln] = ind2sub(size(facs),ind1);
facs(ind1) = facs(rown);
w3d(i).knx = facs;
if i > 1 & i > nc(1), color(i,1:3) = color(1,1:3); end % extend color array to cover all elements 
w3d(i).color = color(i,1:3);
w3d(i).polynum = polynum(i);
if i > ts(2) | trnsp(i)==0, 
    trnsp(i) = 1; 
end % extend transparency array to cover all elements 
w3d(i).trans = trnsp(i);
end

fclose(fp);

%  END OF FUNCTION read_vrml

%=====================================================================================

在这里，我刚刚用我的vrml文件sub1.wrl替换了文件名。 它给出了以下错误

读取vrml 使用读取vrml第31行时出错 输入参数不足

如果我编辑…函数[nel，w3d，infoline]=read\u vrml i、 e仅在文件名第一次出现的位置输入任何内容。 这是错误的

读取vrml 未定义的变量sub1或类sub1.wrl

读取vrml第31行时出错 fp=fopensub1.wrl，'r'

语法方面 VRML智能

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最干净/最直接的方法是使用regex等人对.wrl文件进行预处理，以检索VRML代码分解的[x，y，z]数据，并允许对其进行管道处理

我认为您误解了函数的使用方式

将函数保存到matlab目录中。 然后在控制台/脚本中调用如下函数：

MySurf=read_vrml('sub1.wrl');

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如果尝试在函数定义中使用文件名而不是参数，则会失败。此外，在Matlab中，文件名是字符串数组，您需要使用引号来标识字符串。

您是否研究过此问题：@CapeCode是的，我有。我下载了代码，但它给出了错误。我的.wrl文件名为sub1.wrl。当我输入这个而不是文件名时，它会给出一个错误，表示需要更多参数。您能帮我解决这个问题真是太好了。请用您的代码和准确的错误信息编辑您的问题。@CapeCode您现在可以检查一下了吗。我的建议有什么进展吗？这是错误的语法。我们不使用双引号。谢谢你的评论，马哈。重要的是想法，而不是语法问题。

MySurf=read_vrml('sub1.wrl');