%gaussian2d.m
%Create a 3D printable 2D Plot of Gaussian curve in standard deviation
%segments
%Steven Sahyun October 27, 2015

clear;
clf();
center = 0;

%The x values here are setting the depth of the print.
xplotwidth = 20;
xmin = center-xplotwidth;
xmax = center+xplotwidth;
xstep = (xmax-xmin)/100; %100 data points
x = xmin:xstep:xmax;

%Change these y values to affect the shape of the graph. You can change the
%begining and end points for "plotting" by changing ymin and ymax.
ystddev = 10;
yplotwidth = 40;
ymin = center-4*ystddev; %Change the start point in terms of # of standard deviations
ymax = center+4*ystddev; %Change the end point in terms of # of standard deviations
ystep = (ymax-ymin)/100; %100 data points
y = ymin:ystep:ymax;


xstddev = 10;
%xwidth = sqrt(2)*xstddev;
xwidth = 100; %This is a large value to produce a 2D plot.

%ywidth is the y standard devivation * sqrt (2) since the denominator in the 
% exponential is 2*stddev^2 
ywidth = sqrt(2)*ystddev;
%ywidth = 1;

zscale = 500/(xstddev*sqrt(2*pi)); %500 seems to be a good amplitude based on width of 40.
z = zscale*exp(-((y-center)./ywidth).^2)'*exp(-((x-center)./xwidth).^2);

%Provide a border with height of 0 that is 10 columns wide.
%get size of z, m = rows, n=columns
[m, n] = size(z);
z(:,1:10)=0;
z(:,n-10:n)=0; 

%Plot the surface
surf(x,y,z);
axis([center-xplotwidth, center+xplotwidth, center-yplotwidth, center+yplotwidth, 0, zscale])

%Convert to a 3D printable file; You need to have stlwrite.m and surf2solid.m by
%Sven Holcombe in the same directory as this file.
%See: http://jmumakerlab.blogspot.com/2013/11/exporting-stl-from-matlab.html
% http://www.mathworks.com/matlabcentral/fileexchange/42876-surf2solid-make-a-solid-volume-from-a-surface-for-3d-printing
% http://www.mathworks.com/matlabcentral/fileexchange/20922-stlwrite-filename--varargin-

%minz = 0;
%maxz = zscale;
%c=255*((z+minz)/maxz);

GaussianSurface = surf2solid(x, y, z, 'ELEVATION', -0.5); %Can change Elevation for a thicker base.
stlwrite('GaussianSurfacestl.stl',GaussianSurface)