function cad2matdemo(filename)
% CAD2MATDEMO, a demonstration of importing 3D CAD data into Matlab.
% To get CAD data into Matlab, the process is:
%
% 1) Export the 3D CAD data as an ASCII STL (or Pro/E render SLP) file.
% 2) This Matlab routine reads the CAD data
% 3) Once read, the CAD data is rotated around a bit.
%
% Program has been tested with: AutoCAD, Cadkey, and Pro/Engineer.
% Should work with most any CAD programs that can export STL.
%
% Format Details: STL is supported, and the color version of STL
% that Pro/E exports, called 'render.' The render (SLP) is just
% like STL but with color added.
%
% Note: This routine has both the import function and some basic
% manipulation for testing. The actual reading mechanism is located
% at the end of this file.
if nargin == 0
filename = 'hook.stl'; % a simple demo part
warning(['No file specified, using demo file: ' filename]);
end
%
% Read the CAD data file:
[F, V, C] = rndread(filename);
clf;
p = patch('faces', F, 'vertices' ,V);
%set(p, 'facec', 'b'); % Set the face color (force it)
set(p, 'facec', 'flat'); % Set the face color flat
set(p, 'FaceVertexCData', C); % Set the color (from file)
%set(p, 'facealpha',.4) % Use for transparency
set(p, 'EdgeColor','none'); % Set the edge color
%set(p, 'EdgeColor',[1 0 0 ]); % Use to see triangles, if needed.
light % add a default light
daspect([1 1 1]) % Setting the aspect ratio
view(3) % Isometric view
xlabel('X'),ylabel('Y'),zlabel('Z')
title(['Imported CAD data from ' filename])
drawnow %, axis manual
%
disp(['CAD file ' filename ' data is read, will now show object rotating'])
pause(1)
%
% Move it around.
% To use homogenous transforms, the n by 3 Vertices will be turned to
% n by 4 vertices, then back to 3 for the set command.
% Note: n by 4 needed for translations, not used here, but could, using tl(x,y,z)
V = V';
V = [V(1,:); V(2,:); V(3,:); ones(1,length(V))];
%
vsize = maxv(V); %attempt to determine the maximum xyz vertex.
AXIS([-vsize vsize -vsize vsize -vsize vsize]);
%
for ang = 0:1:90
nv = rx(ang)*V;
set(p,'Vertices',nv(1:3,:)')
drawnow
end
for ang1 = 0:2:90
nv1 = ry(ang1)*nv;
set(p,'Vertices',nv1(1:3,:)')
drawnow
end
for ang2 = 0:3:90
nv2= rz(ang2)*nv1;
set(p,'Vertices',nv2(1:3,:)')
drawnow
end
for ang3 = 0:5:180
nv3 = rx(ang3)*ry(ang3)*rz(ang3)*nv2;
set(p,'Vertices',nv3(1:3,:)')
drawnow
end
%
% End of main routine, here are the functions used:
% Homogeneous manipulation functions follow:
%
function Rx = rx(THETA)
% ROTATION ABOUT THE X-AXIS
%
% Rx = rx(THETA)
%
% This is the homogeneous transformation for
% rotation about the X-axis.
%
% NOTE: The angle THETA must be in DEGREES.
%
THETA = THETA*pi/180; % Note: THETA in radians.
c = cos(THETA);
s = sin(THETA);
Rx = [1 0 0 0; 0 c -s 0; 0 s c 0; 0 0 0 1];
%
function Ry = ry(THETA)
% ROTATION ABOUT THE Y-AXIS
%
% Ry = ry(THETA)
%
% This is the homogeneous transformation for
% rotation about the Y-axis.
%
% NOTE: The angel THETA must be in DEGREES.
%
THETA = THETA*pi/180; %Note: THETA is in radians.
c = cos(THETA);
s = sin(THETA);
Ry = [c 0 s 0; 0 1 0 0; -s 0 c 0; 0 0 0 1];
%
function Rz = rz(THETA)
% ROTATION ABOUT THE Z-AXIS
%
% Rz = rz(THETA)
%
% This is the homogeneous transformation for
% rotation about the Z-axis.
%
% NOTE: The angle THETA must be in DEGREES.
%
THETA = THETA*pi/180; %Note: THETA is in radians.
c = cos(THETA);
s = sin(THETA);
Rz = [c -s 0 0; s c 0 0; 0 0 1 0; 0 0 0 1];
%
function T = tl(x,y,z)
% TRANSLATION ALONG THE X, Y, AND Z AXES
%
% T = tl(x,y,z)
%
% This is the homogeneous transformation for
% translation along the X, Y, and Z axes.
%
T = [1 0 0 x; 0 1 0 y; 0 0 1 z; 0 0 0 1];
%
function vsize = maxv(V)
%
% Look at the xyz elements of V, and determine the maximum
% values during some simple rotations.
vsize = max(max(V));
% Rotate it a bit, and check for max and min vertex for viewing.
for ang = 0:10:360
vsizex = rx(ang)*V;
maxv = max(max(vsizex));
if maxv > vsize, vsize = maxv; end
vsizey = ry(ang)*V;
maxv = max(max(vsizey));
if maxv > vsize, vsize = maxv; end
vsizez = rz(ang)*V;
maxv = max(max(vsizez));
if maxv > vsize, vsize = maxv; end
vsizev = rx(ang)*ry(ang)*rz(ang)*V;
maxv = max(max(vsizev));
if maxv > vsize, vsize = maxv; end
end
%
function [fout, vout, cout] = rndread(filename)
% Reads CAD STL ASCII files, which most CAD programs can export.
% Used to create Matlab patches of CAD 3D data.
% Returns a vertex list and face list, for Matlab patch command.
%
% filename = 'hook.stl'; % Example file.
%
fid=fopen(filename, 'r'); %Open the file, assumes STL ASCII format.
if fid == -1
error('File could not be opened, check name or path.')
end
%
% Render files take the form:
%
%solid BLOCK
% color 1.000 1.000 1.000
% facet
% normal 0.000000e+00 0.000000e+00 -1.000000e+00
% normal 0.000000e+00 0.000000e+00 -1.000000e+00
% normal 0.000000e+00 0.000000e+00 -1.000000e+00
% outer loop
% vertex 5.000000e-01 -5.000000e-01 -5.000000e-01
% vertex -5.000000e-01 -5.000000e-01 -5.000000e-01
% vertex -5.000000e-01 5.000000e-01 -5.000000e-01
% endloop
% endfacet
%
% The first line is object name, then comes multiple facet and vertex lines.
% A color specifier is next, followed by those faces of that color, until
% next color line.
%
CAD_object_name = sscanf(fgetl(fid), '%*s %s'); %CAD object name, if needed.
% %Some STLs have it, some don't.
vnum=0; %Vertex number counter.
report_num=0; %Report the status as we go.
VColor = 0;
%
while feof(fid) == 0 % test for end of file, if not then do stuff
tline = fgetl(fid); % reads a line of data from file.
fword = sscanf(tline, '%s '); % make the line a character string
% Check for color
if strncmpi(fword, 'c',1) == 1; % Checking if a "C"olor line, as "C" is 1st char.
VColor = sscanf(tline, '%*s %f %f %f'); % & if a C, get the RGB color data of the face.
end % Keep this color, until the next color is used.
if strncmpi(fword, 'v',1) == 1; % Checking if a "V"ertex line, as "V" is 1st char.
vnum = vnum + 1; % If a V we count the # of V's
report_num = report_num + 1; % Report a counter, so long files show status
if report_num > 249;
disp(sprintf('Reading vertix num: %d.',vnum));
report_num = 0;
end
v(:,vnum) = sscanf(tline, '%*s %f %f %f'); % & if a V, get the XYZ data of it.
c(:,vnum) = VColor; % A color for each vertex, which will color the faces.
end % we "*s" skip the name "color" and get the data.
end
% Build face list; The vertices are in order, so just number them.
%
fnum = vnum/3; %Number of faces, vnum is number of vertices. STL is triangles.
flist = 1:vnum; %Face list of vertices, all in order.
F = reshape(flist, 3,fnum); %Make a "3 by fnum" matrix of face list data.
%
% Return the faces and vertexs.
%
fout = F'; %Orients the array for direct use in patch.
vout = v'; % "
cout = c';
%
fclose(fid);
