visualizeRay.m

function visualizeRay(R,c,E,U,V,l,r,t,b,nx,ny, e,s,P1,P2, showgrid)
%% To visualize the raytracing simulation
%%

leni = (r-l)/nx;
lenj = (t-b)/ny;

ul = computeGrid(E,l,t,U,V);
ll = computeGrid(E,l,b,U,V);
ur = computeGrid(E,r,t,U,V);
lr = computeGrid(E,r,b,U,V);

[x,y,z] = sphere;

if(showgrid==1)
    showGrid(nx,ny,E,U,V,leni,lenj,l,r,t,b);
end

plot3([ul(1), ur(1), lr(1), ll(1), ul(1)], [ul(2), ur(2), lr(2), ll(2),...
   ul(2)], [ul(3), ur(3), lr(3), ll(3), ul(3)], 'r-','LineWidth',2);
% patch([ul(1), ur(1), lr(1), ll(1), ul(1)], [ul(2), ur(2), lr(2), ll(2),...
%      ul(2)], [ul(3), ur(3), lr(3), ll(3), ul(3)], '-','LineWidth',2, 'EdgeColor','r','FaceColor','b','FaceAlpha',0.2);
% ax = gca;
% ax.CameraPosition = [150, 200, 220];
% ax.CameraUpVector = [0 1 0];

hold on;
plot3([e(1), s(1)], [e(2), s(2)], [e(3), s(3)], 'k-','LineWidth', 1);
hold on;
plot3(e(1), e(2), e(3), 'bs','MarkerFaceColor','b');
hold on;
surf(x*R+c(1),y*R+c(2),z*R+c(3), 'EdgeColor','none');
hold on;
plot3([P1(1), P2(1)],[P1(2), P2(2)],[P1(3), P2(3)], 'ko','MarkerFaceColor','k');
hold off;
grid on;
grid minor;
box on;
axis equal;
xlabel('X');
ylabel('Y');
zlabel('Z');
ax = gca;
ax.CameraPosition = [150, 200, 220];
ax.CameraUpVector = [0 1 0];

end

function m = computeGrid(E,p,q,U,V)
m = E + p*U + q*V;
end

function showGrid(nx,ny,E,U,V,leni,lenj,l,r,t,b)
g1 = [];
h1 = [];
dl = l;
for n = 1:nx-1
    dl = dl + leni;
    g1 = [g1 computeGrid(E,dl,t,U,V);];
    h1 = [h1 computeGrid(E,dl,b,U,V);];
end
g1 = g1';
h1 = h1';

g2 = [];
h2 = [];
dt = t;
for n = 1:ny-1
    dt = dt - lenj;
    g2 = [g2 computeGrid(E,l,dt,U,V);];
    h2 = [h2 computeGrid(E,r,dt,U,V);];
end
g2 = g2';
h2 = h2';


plot3([g1(:,1)'; h1(:,1)'], [g1(:,2)'; h1(:,2)'], [g1(:,3)'; h1(:,3)'], 'b-');
hold on;
plot3([g2(:,1)'; h2(:,1)'], [g2(:,2)'; h2(:,2)'], [g2(:,3)'; h2(:,3)'], 'b-');
hold on;
end