hIm = imshow(imread('coins.png'));
hIm.ButtonDownFcn = @(~,~) buttonPressedCallback(hIm.Parent);
 
function buttonPressedCallback(hAx)
    cp = hAx.CurrentPoint;
    cp = [cp(1,1) cp(1,2)];
    obj = images.roi.Line('Parent',hAx,'Color',rand([1,3]));
    beginDrawingFromPoint(obj,cp);
end

sampleDrawLine

function cuboidExample
    [x,y,z] = sphere(16);
    X = [x(:)*.5 x(:)*.75 x(:)];
    Y = [y(:)*.5 y(:)*.75 y(:)];
    Z = [z(:)*.5 z(:)*.75 z(:)];
    
    % Specify the size and color of each marker.
    S = repmat([1 .75 .5]*10,numel(x),1);
    C = repmat([1 2 3],numel(x),1);
    
    % Create a 3-D scatter plot
    figure
    hScatter = scatter3(X(:),Y(:),Z(:),S(:),C(:),'filled'); 
    view(-60,60);
 
    % Begin drawing cuboids when a scatter
    % point is clicked
    hScatter.ButtonDownFcn = @(~,~) buttonPressedCallback(hScatter.Parent);
   
    function buttonPressedCallback(hAx)
       cp = hAx.CurrentPoint;
       cp = cp(1,1:3);
       obj = images.roi.Cuboid('Parent',hAx,'Color',rand([1,3]));
       obj.beginDrawingFromPoint(cp);
    end
 end

cuboidExample