% Author : Jan Markowski
%
% This MATLAB program simply shows how the raw coordinates that are
% inputted into the Wii-remote become translated to correspond to specific
% coordinates on the screen. These are the same calculations that are made
% in the Java program, wiiBoardJ.java.
%
% When you run this default program, zoom into the bottom left of the plot
% to see the original raw coordinates.

% Sample of x,y source coordinates for Points 1, 2, 3, and 4.
ssc = [0.02932551319648094,0.6675358539765319;
    0.4066471163245357,0.6597131681877445;
    0.42130987292277616,0.2920469361147327;
    0.03421309872922776,0.34159061277705344]
% Sample of x,y coordinates of a random point (for curiosity of how it gets
% translated.)
sp = [0.1495601173020528,0.4511082138200782]
% Input the screen size
screenx = 1680;
screeny = 1250;

% Translate Coordinates
sscTrans = ssc;
spTrans = sp;

sscTrans(:,1) = sscTrans(:,1)-ssc(4,1);
spTrans(1) = spTrans(1)-ssc(4,1);
sscTrans(:,2) = sscTrans(:,2)-ssc(4,2);
spTrans(2) = spTrans(2)-ssc(4,2);

% Shear vertically
shearY = sscTrans(3,2)/sscTrans(3,1);

sscShear = sscTrans;
spShear = spTrans;

sscShear(:,2) = sscShear(:,2)-sscShear(:,1)*shearY;
spShear(2) = spShear(2)-spShear(1)*shearY;

% Shear horizontally
shearX = sscShear(1,1)/sscShear(1,2);

sscShear(:,1) = sscShear(:,1)-sscShear(:,2)*shearX;
spShear(1) = spShear(1)-spShear(2)*shearX;

% Make top segment parallel to bottom.
slope12 = (1-sscShear(2,2)/sscShear(1,2))/sscShear(2,1);
inter12 = sscShear(2,2)/sscShear(1,2);

sscShear(1,2) = sscShear(1,2)*(slope12*sscShear(1,1) + inter12);
spShear(2) = spShear(2)*(slope12*spShear(1) + inter12);

% Make right segment parallel to right.
slope23 = (1-sscShear(2,1)/sscShear(3,1))/sscShear(2,2);
inter23 = sscShear(2,1)/sscShear(3,1);

sscShear(3,1) = sscShear(3,1)*(slope23*sscShear(3,2) + inter23);
spShear(1) = spShear(1)*(slope23*spShear(2) + inter23);

% Scale
scaleX = screenx/sscShear(2,1);
scaleY = screeny/sscShear(2,2);

sscShear(:,1) = sscShear(:,1)*scaleX;
sscShear(:,2) = sscShear(:,2)*scaleY;
spShear(1) = spShear(1)*scaleX;
spShear(2) = spShear(2)*scaleY;

plot(ssc(:,1),ssc(:,2),'-b', sp(1), sp(2), 'ob', sscTrans(:,1),sscTrans(:,2),'-r', spTrans(1), spTrans(2), 'or', sscShear(:,1),sscShear(:,2),'-m', spShear(1), spShear(2), 'om')