% 6.581 PS3 Qsn1
% loadComplx.m

r = 0.4;  % radius of ligand (radius of complex is 1)
sepX = 1-r;
% Receptor and Ligand charge locaitons
Rcharges = [-0.8   0   0.5;
              0   0.6  0.5;
              0  -0.6  0.5;
            -0.8   0  -0.5;
              0   0.6 -0.5;
              0  -0.6 -0.5];             
Lcharges = [-0.5 -0.5  0;
            -0.5  0.5  0;
             0.5  0.5  0; 
             0.5 -0.5  0];
Lcharges = r*Lcharges;
Lcharges(:,1) = Lcharges(:,1) + sepX;


% visualize ligand and ligand-receptor complex
[X,Y,Z] = sphere(20);
[TH,PHI,R] = cart2sph(X,Y,Z);
[XL,YL,ZL] = sph2cart(TH,PHI,r);
XL = XL + sepX;
surf(X,Y,Z)
hold on
surf(XL,YL,ZL,ones(size(Z)))
shading interp
alpha(0.3)

th = linspace(0,2*pi,200);
plot(r*cos(th)+sepX,r*sin(th),'r:','Linewidth',2)
plot(cos(th),sin(th),'b:','Linewidth',2)
plot3(Rcharges(:,1),Rcharges(:,2),Rcharges(:,3),'b.','MarkerSize',20)
plot3(Lcharges(:,1),Lcharges(:,2),Lcharges(:,3),'r.','MarkerSize',20)
hold off
axis equal
axis off
text(sepX,0,'Ligand','FontSize',15,'Color','r','HorizontalAlignment','center')
text(-sepX/2,0,'Receptor','FontSize',15,'Color','b','HorizontalAlignment','center')