stlread implemented in octave

stlread.m

@@ -0,0 +1,106 @@
+function [vertices, faces, color] = stlread(filename)
+% This function reads an STL file in binary format into matrixes vertices
+% and faces which can be used by patch to view the stl.
+%
+% MATLAB code by Doron Harlev
+% Octave edits by John Moosemiller && @zmughal
+
+read_norm = 0; % whether we want to read the face normals
+
+% Process arguments {{{
+if nargout > 3
+    error('Too many output arguments');
+end
+use_color = ( nargout == 3 );% }}}
+
+% Open the file, assumes STL Binary format. {{{
+if ( fid = fopen(filename, 'r') ) == -1;
+    error('File could not be opened, check name or path.')
+end% }}}
+
+% Read in header {{{
+ftitle = fread(fid, 80, 'uchar=>schar'); % Read file title
+num_facet = fread(fid, 1, 'int32'); % Read number of Facets
+
+fprintf('\nTitle: %s\n', char(ftitle'));
+fprintf('Num Facets: %d\n', num_facet);
+% }}}
+
+% Preallocate memory to save running time {{{
+vertices = zeros( 3 * num_facet, 3 );
+faces    = zeros(     num_facet, 3 );
+if use_color
+    color = uint8( zeros( 3, num_facet ) );
+end
+% }}}
+
+% Read in packed data for each face {{{
+coord_sz = 3*32/8; % [bytes] size of vertex coordinates (x,y,z) '3*float32'
+color_sz = 1*16/8; % [bytes] size of color data: '1*uint16'
+block_sz = 4*coord_sz + color_sz; % [bytes] 4 coords (norm, v1, v2, v3) + 1 color data
+
+% get the start of where the face data is in the file
+fid_face_data_start = ftell( fid );
+
+% Read norm of the face [1*coord_sz] {{{
+start_offset = 0; % at fid_face_data_start + 0
+if read_norm
+	norm = fread( fid, [3, num_facet], '3*float32', block_sz - coord_sz );
+end
+start_offset = start_offset + 1*coord_sz;% }}}
+% Read all 3 vertices of each face [3*coord_sz] {{{
+% Each column is the 3 vertices with 3 coords each for each face
+% face_vertices =
+%       f1_v_1x  f2_v_1x ... fN_v_1x
+%       f1_v_1y  f2_v_1y ... fN_v_1y
+%       f1_v_1z  f2_v_1z ... fN_v_1z
+%       f1_v_2x  f2_v_2x ... fN_v_2x
+%       f1_v_2y  f2_v_2y ... fN_v_2y
+%       f1_v_2z  f2_v_2z ... fN_v_2z
+%       f1_v_3x  f2_v_3x ... fN_v_3x
+%       f1_v_3y  f2_v_3y ... fN_v_3y
+%       f1_v_3z  f2_v_3z ... fN_v_3z
+fseek( fid, fid_face_data_start + start_offset );
+face_vertices = fread( fid, [3*3, num_facet], '9*float32', block_sz - 3*coord_sz );
+start_offset = start_offset + 3*coord_sz;% }}}
+% Read the color of each face [1*color_sz] {{{
+if use_color
+	fseek( fid, fid_face_data_start + start_offset );
+	col  = fread( fid, num_facet, '1*uint16', block_sz - 1*color_sz );% }}}
+end
+% }}}
+
+% Reshape data into faces and vertices {{{
+% interleave vertices {{{
+% so that we get
+% vertices =
+%        f1_v_1x f1_v_1y f1_v_1z
+%        f1_v_2x f1_v_2y f1_v_2z
+%        f1_v_3x f1_v_3y f1_v_3z
+%        f2_v_3x f2_v_3y f2_v_3z
+%        ...     ...     ...
+%        fN_v_2x fN_v_2y fN_v_2z
+%        fN_v_3x fN_v_3y fN_v_3z
+vertices = reshape(face_vertices(:), 3, [])';% }}}
+% face triangle vertices are in sequential rows of `vertices`% {{{
+% faces =
+%        1    2    3
+%        4    5    6
+%        .    .    .
+%        3N-2 3N-1 3N
+faces = reshape( 1:3*num_facet, 3, [])';% }}}
+% extract color from bits% {{{
+if use_color && any(col)
+	valid = bitget(col,16) == 1;
+	r = bitshift( bitand(2^16-1, col), -10 );
+	g = bitshift( bitand(2^11-1, col), -5  );
+	b = bitand(2^6-1, col);
+
+	% only keep the valid color data, set other to zero (black)
+	color = [r g b] .* valid;
+end% }}}
+% }}}
+
+fclose(fid);
+
+% For more information on the stl binary format - http://rpdrc.ic.polyu.edu.hk/old_files/stl_binary_format.htm