matlab开发-surf2stl

function surf2stl(filename,x,y,z,mode) %SURF2STL Write STL file from surface data. % SURF2STL('filename',X,Y,Z) writes a stereolithography (STL) file % for a surface with geometry defined by three matrix arguments, X, Y % and Z. X, Y and Z must be two-dimensional arrays with the same size. % % SURF2STL('filename',x,y,Z), uses two vector arguments replacing % the first two matrix arguments, which must have length(x) = n and % length(y) = m where [m,n] = size(Z). Note that x corresponds to % the columns of Z and y corresponds to the rows. % % SURF2STL('filename',dx,dy,Z) uses scalar values of dx and dy to % specify the x and y spacing between grid points. % % SURF2STL(...,'mode') may be used to specify the output format. % % 'binary' - writes in STL binary format (default) % 'ascii' - writes in STL ASCII format % % Example: % % surf2stl('test.stl',1,1,peaks); % % See also SURF. % % Author: Bill McDonald, 02-20-04 error(nargchk(4,5,nargin)); if (ischar(filename)==0) error( 'Invalid filename'); end if (nargin < 5) mode = 'binary'; elseif (strcmp(mode,'ascii')==0) mode = 'binary'; end if (ndims(z) ~= 2) error( 'Variable z must be a 2-dimensional array' ); end if any( (size(x)~=size(z)) | (size(y)~=size(z)) ) % size of x or y does not match size of z if ( (length(x)==1) & (length(y)==1) ) % Must be specifying dx and dy, so make vectors dx = x; dy = y; x = ((1:size(z,2))-1)*dx; y = ((1:size(z,1))-1)*dy; end if ( (length(x)==size(z,2)) & (length(y)==size(z,1)) ) % Must be specifying vectors xvec=x; yvec=y; [x,y]=meshgrid(xvec,yvec); else error('Unable to resolve x and y variables'); end end if strcmp(mode,'ascii') % Open for writing in ascii mode fid = fopen(filename,'w'); else % Open for writing in binary mode fid = fopen(filename,'wb+'); end if (fid == -1) error( sprintf('Unable to write to %s',filename) ); end title_str = sprintf('Created by surf2stl.m %s',datestr(now)); if strcmp(mode,'ascii') fprintf(fid,'solid %s\r\n',title_str); else str = sprintf('%-80s',title_str); fwrite(fid,str,'uchar'); % Title fwrite(fid,0,'int32'); % Number of facets, zero for now end nfacets = 0; for i=1:(size(z,1)-1) for j=1:(size(z,2)-1) p1 = [x(i,j) y(i,j) z(i,j)]; p2 = [x(i,j+1) y(i,j+1) z(i,j+1)]; p3 = [x(i+1,j+1) y(i+1,j+1) z(i+1,j+1)]; val = local_write_facet(fid,p1,p2,p3,mode); nfacets = nfacets + val; p1 = [x(i+1,j+1) y(i+1,j+1) z(i+1,j+1)]; p2 = [x(i+1,j) y(i+1,j) z(i+1,j)]; p3 = [x(i,j) y(i,j) z(i,j)]; val = local_write_facet(fid,p1,p2,p3,mode); nfacets = nfacets + val; end end if strcmp(mode,'ascii') fprintf(fid,'endsolid %s\r\n',title_str); else fseek(fid,0,'bof'); fseek(fid,80,'bof'); fwrite(fid,nfacets,'int32'); end fclose(fid); disp( sprintf('Wrote %d facets',nfacets) ); % Local subfunctions function num = local_write_facet(fid,p1,p2,p3,mode) if any( isnan(p1) | isnan(p2) | isnan(p3) ) num = 0; return; else num = 1; n = local_find_normal(p1,p2,p3); if strcmp(mode,'ascii') fprintf(fid,'facet normal %.7E %.7E %.7E\r\n', n(1),n(2),n(3) ); fprintf(fid,'outer loop\r\n'); fprintf(fid,'vertex %.7E %.7E %.7E\r\n', p1); fprintf(fid,'vertex %.7E %.7E %.7E\r\n', p2); fprintf(fid,'vertex %.7E %.7E %.7E\r\n', p3); fprintf(fid,'endloop\r\n'); fprintf(fid,'endfacet\r\n'); else fwrite(fid,n,'float32'); fwrite(fid,p1,'float32'); fwrite(fid,p2,'float32'); fwrite(fid,p3,'float32'); fwrite(fid,0,'int16'); % unused end end function n = local_find_normal(p1,p2,p3) v1 = p2-p1; v2 = p3-p1; v3 = cross(v1,v2); n = v3 ./ sqrt(sum(v3.*v3));