function varargout = stlread(file)
% STLREAD imports geometry from an STL file into MATLAB.
% FV = STLREAD(FILENAME) imports triangular faces from the ASCII or binary
% STL file idicated by FILENAME, and returns the patch struct FV, with fields
% 'faces' and 'vertices'.
%
% [F,V] = STLREAD(FILENAME) returns the faces F and vertices V separately.
%
% [F,V,N] = STLREAD(FILENAME) also returns the face normal vectors.
%
% The faces and vertices are arranged in the format used by the PATCH plot
% object.
% Copyright 2011 The MathWorks, Inc.
if ~exist(file,'file')
error(['File ''%s'' not found. If the file is not on MATLAB''s path' ...
', be sure to specify the full path to the file.'], file);
end
fid = fopen(file,'r');
if ~isempty(ferror(fid))
error(lasterror); %#ok
end
M = fread(fid,inf,'uint8=>uint8');
fclose(fid);
[f,v,n] = stlbinary(M);
%if( isbinary(M) ) % This may not be a reliable test
% [f,v,n] = stlbinary(M);
%else
% [f,v,n] = stlascii(M);
%end
varargout = cell(1,nargout);
switch nargout
case 2
varargout{1} = f;
varargout{2} = v;
case 3
varargout{1} = f;
varargout{2} = v;
varargout{3} = n;
otherwise
varargout{1} = struct('faces',f,'vertices',v);
end
end
function [F,V,N] = stlbinary(M)
F = [];
V = [];
N = [];
if length(M) < 84
error('MATLAB:stlread:incorrectFormat', ...
'Incomplete header information in binary STL file.');
end
% Bytes 81-84 are an unsigned 32-bit integer specifying the number of faces
% that follow.
numFaces = typecast(M(81:84),'uint32');
%numFaces = double(numFaces);
if numFaces == 0
warning('MATLAB:stlread:nodata','No data in STL file.');
return
end
T = M(85:end);
F = NaN(numFaces,3);
V = NaN(3*numFaces,3);
N = NaN(numFaces,3);
numRead = 0;
while numRead < numFaces
% Each facet is 50 bytes
% - Three single precision values specifying the face normal vector
% - Three single precision values specifying the first vertex (XYZ)
% - Three single precision values specifying the second vertex (XYZ)
% - Three single precision values specifying the third vertex (XYZ)
% - Two unused bytes
i1 = 50 * numRead + 1;
i2 = i1 + 50 - 1;
facet = T(i1:i2)';
n = typecast(facet(1:12),'single');
v1 = typecast(facet(13:24),'single');
v2 = typecast(facet(25:36),'single');
v3 = typecast(facet(37:48),'single');
n = double(n);
v = double([v1; v2; v3]);
% Figure out where to fit these new vertices, and the face, in the
% larger F and V collections.
fInd = numRead + 1;
vInd1 = 3 * (fInd - 1) + 1;
vInd2 = vInd1 + 3 - 1;
V(vInd1:vInd2,:) = v;
F(fInd,:) = vInd1:vInd2;
N(fInd,:) = n;
numRead = numRead + 1;
end
end
function [F,V,N] = stlascii(M)
warning('MATLAB:stlread:ascii','ASCII STL files currently not supported.');
F = [];
V = [];
N = [];
end
% TODO: Change the testing criteria! Some binary STL files still begin with
% 'solid'.
function tf = isbinary(A)
% ISBINARY uses the first line of an STL file to identify its format.
if isempty(A) || length(A) < 5
error('MATLAB:stlread:incorrectFormat', ...
'File does not appear to be an ASCII or binary STL file.');
end
if strcmpi('solid',char(A(1:5)'))
tf = false; % ASCII
else
tf = true; % Binary
end
end
