Does anybody know how should I use animatedline in

Question

This is the main code

%%%%%%%%%%%% Valori pentru Rcsc


%%%%Pozitiile si vitezele pe cele 3 axe

y0(1,1)=   743322.3616  ;                                     
y0(2,1)=   -6346021.219 ;                               
y0(3,1)=     -3394131.349 ;                                   
y0(4,1)=     5142.38067;        
y0(5,1)=   4487.44895   ;                    
y0(6,1)=     -7264.00872;                     
%%%% Timpul

tspan=[0 :864]; 

%%%% Masa(kg) si aria suprafetei satelitului (m^2)

m =    217 ;         %320;
A =   1.2;             %8;

%%%% Metoda Runge-Kutta de ordin 4

h=1;                                                                             
y = zeros(6, tspan(end)/h); 
y(:,1) = y0;

for i=1:(tspan(end)/h)    
    H=sqrt(y(1,i)^2+y(2,i)^2+y(3,i)^2);
    k_1 = proiectia(tspan(i), y(:,i), H, m, A, y(4:6, i));
    k1=double(k_1);
    k_2 = proiectia(tspan(i)+0.5*h, y(:,i)+0.5*h*k_1, H, m, A, y(4:6, i));
    k2=double(k_2);
    k_3 = proiectia((tspan(i)+0.5*h), (y(:,i)+0.5*h*k_2), H, m, A, y(4:6, i));
    k3=double(k_3);
    k_4 = proiectia((tspan(i)+h),(y(:,i)+k_3*h), H, m, A, y(4:6, i));
    k4=double(k_4);

    y(:,i+1) = double(y(:,i) + (1/6)*(k1+2*k2+2*k3+k4)*h);  

end


%%% Distanta satelitului
Rcsc = ((y(1,:).^2 + y(2,:).^2 + y(3,:).^2).^0.5);
n=50;
%plot(tspan,Rcsc)
 %% Textured 3D Earth example
%
% Ryan Gray
% 8 Sep 2004
% Revised 9 March 2006, 31 Jan 2006, 16 Oct 2013

%% Options

space_color = 'k';
npanels = 180;   % Number of globe panels around the equator deg/panel = 360/npanels
alpha   = 1; % globe transparency level, 1 = opaque, through 0 = invisible
GMST0 = []; % Don't set up rotatable globe (ECEF)
%GMST0 = 4.89496121282306; % Set up a rotatable globe at J2000.0

% Earth texture image
% Anything imread() will handle, but needs to be a 2:1 unprojected globe
% image.

image_file = 'https://upload.wikimedia.org/wikipedia/commons/thumb/c/cd/Land_ocean_ice_2048.jpg/1024px-Land_ocean_ice_2048.jpg';

% Mean spherical earth

erad    = 6371008.7714; % equatorial radius (meters)
prad    = 6371008.7714; % polar radius (meters)
erot    = 7.2921158553e-5; % earth rotation rate (radians/sec)

%% Create figure

figure('Color', space_color);


hold on;
 orbit=animatedline;
addpoints(orbit,y(1,:),y(2,:),y(3,:));
drawnow

% Turn off the normal axes

set(gca, 'NextPlot','add', 'Visible','off');

axis equal;
axis auto;

% Set initial view

view(0,30);

axis vis3d;

%% Create wireframe globe

% Create a 3D meshgrid of the sphere points using the ellipsoid function

[x, y, z] = ellipsoid(0, 0, 0, erad, erad, prad, npanels);

globe = surf(x, y, -z, 'FaceColor', 'none', 'EdgeColor', 0.5*[1 1 1]);



%% Texturemap the globe

% Load Earth image for texture map

cdata = imread(image_file);

% Set image as color data (cdata) property, and set face color to indicate
% a texturemap, which Matlab expects to be in cdata. Turn off the mesh edges.

set(globe, 'FaceColor', 'texturemap', 'CData', cdata, 'FaceAlpha', alpha, 'EdgeColor', 'none');

What I wanna do is that when I run the script a figure with the Earth should appear, and while the positions are being caluclated by the runge kutta algorithm it should upload the orbit in real time. But now the figure appears only after the Rk algorithm is being calculated till the end of tspan and the orbit from the figure is already uploaded without intermediate points. What should I do? I've seen on github that others use animatedline and drawnow. I was thinking about

 orbit=animatedline;

    addpoints(orbit,y(1,:),y(2,:),y(3,:));
    drawnow
    end

But where should I put this line exactly? if I put it in the rk loop it doesn't work and if I put it

% Create figure
figure('Color', space_color);
%%
orbit=animatedline;
addpoints(orbit,y(1,:),y(2,:),y(3,:));
drawnow

it first displays a figure with the orbit but not by intermediate points and then a different figure with the Earth ,while the orbit and the Earth should be in the same figure.

Answer 1

You are using animatedline in a wrong way.

The line:

orbit = animatedline;

should be placed before the loop that calculates the points, and the lines:

addpoints(orbit,y(1,i),y(2,i),y(3,i));
drawnow

should be placed within it, to add one (or several) points to the line on each iteration. But, a better approach, would be to first calculate all the orbit and then use a loop for the animation. This way you have more control over the rate of the animation. Here is a small example using your case:

orbit = animatedline;
for k = 1:size(y,2)
    addpoints(orbit,y(1,k),y(2,k),y(3,k));
    drawnow
end

Alternative option

Don't use animated line just keep updating the data in the plot. Here is a simple workout for this:

% create a sphere with earth map on it:
set(gcf,'Color','k')
earth = imread('earth.jpg');
[X,Y,Z] = sphere(50); 
warp(-X,Y,-Z,earth)
axis off
view(-46,17)

% set an animation of a simple orbit:
Nframes = 100; % number of steps in the orbit
% calculation of the orbit:
orb = linspace(-pi,pi,Nframes); 
x = cos(orb).*1.5;
y = sin(orb);
hold on
% plot the whole orbit invisible, just for setting the axes limits:
tmp = plot(x,y,'Color','none');
p = plot(x(1),y(1),'LineWidth',3,'Color','m'); % plot the first step
hold off
for k = 1:numel(orb)
    p.XData = x(1:k); % update the data of the plot
    p.YData = y(1:k);
    pause(0.05) % delay
end

The result: