In the (x,y) plane :
figure
xlim([0 100])
ylim([0 100])
hold on
i = 1
while true
[x(i), y(i)] = ginput(1);
scatter(x(i), y(i),'blue')
p = plot(x,y,Color='blue');
i = i+1;
end
In the (x,y,z) plane you can use the same logic using ginput3d : https://uk.mathworks.com/matlabcentral/fileexchange/34939-ginput-3d
With this function, you need to place yourself in the right plan with the view function each time you add a point, indeed, it is impossible for Matlab to know where in 3D you would like to draw your point.
