Move a scatter3 3D point around using a GUI slider?

Hello,

I placed a 3D point near a surface using scatter3 (in Matlab2012a), and would like to add a slider that can move that point around. I see an example for 2015a that uses updateSystem, but I don't seem to have that: http://www.mathworks.com/help/control/ug/build-app-with-interactive-plot-updates.html

I believe it should be do-able in 2012a...

Here's the code I have so far that makes the surface, and plots a few scatter3 points. It's the point with s= that I would like to move around. I managed only to place 2 sliders so far on the GUI. The plan is to hook slider b up to r, and slider b1 up to x. Hopefully then scatter3 point s moves around.

echo OFF ALL;
f = figure;
[X,Y,Z] = sphere(200);
Z(Z < 0.0) = NaN;
X(X < 0.0) = NaN;
Y(Y < 0.0) = NaN;
quarterSphere = surf(X,Y,Z);
set(quarterSphere,'FaceColor',[0 0 0],'FaceAlpha',0.3,'EdgeColor',[0 0 0],'EdgeAlpha',0.1);
hold on;
% sample calc to place a point on the 1/4 sphere, in any location
r = 0.99; % radius in a plane to get y for a given x, where x <= r
x = 0.1; % x distance within r circle
if x > r
% h = msgbox('x must be <= r');
error('x must be <= r');
end
y=sqrt(r^2-x^2);
z=sqrt(1-x^2-y^2);
s = scatter3(x,y,z,50,[1 0 0],'filled');
scatter3(.5,.5,.5,50,[0 0 0],'filled'); % NPI
scatter3(.6,.8,.2,50,[0 1 0],'filled'); % high Vavg, low CTI
scatter3(.6,.2,.8,50,[0 1 0],'filled'); % low Vavg, high CTI
scatter3(.8,.6,.2,50,[1 1 0],'filled'); % high density, low CTI
scatter3(.2,.6,.8,50,[1 1 0],'filled'); % low density, high CTI
scatter3(.8,.2,.6,50,[0 1 1],'filled'); % high density, low Vavg
scatter3(.2,.8,.6,50,[0 1 1],'filled'); % low density, high Vavg
hold off;
xlabel('density');
ylabel('Vavg');
zlabel('CTI');
view([1 0 0]);
axis square;
b = uicontrol('Parent',f,'Style','slider','units','normalized','Position',[0,.005,.5,.01],'value',x, 'min',0, 'max',1);
blabel = uicontrol('Parent',f,'Style','text','string','r','units','normalized','Position',[0.25,.015,.02,.03]);
b1 = uicontrol('Parent',f,'Style','slider','units','normalized','Position',[.5,.005,.5,.01],'value',x, 'min',0, 'max',1);
b1label = uicontrol('Parent',f,'Style','text','string','x','units','normalized','Position',[0.75,.015,.02,.03]);

Answer 1

[Geoff Hayes]

David - you need to assign a callback to each of your sliders. Try the following - wrap all of your above code in a function block so that you can nest a local function within it. Something like

 function myFunction

     echo OFF ALL;
     f = figure;
     [X,Y,Z] = sphere(200);
     Z(Z < 0.0) = NaN;
     X(X < 0.0) = NaN;
     Y(Y < 0.0) = NaN;

     % etc.

 end

Now assign a callback to each of your sliders as

    b = uicontrol('Parent',f,'Style','slider','units','normalized',...
      'Position', [0,.005,.5,.01],'value',r, 'min',0, 'max',1, ...
      'Callback', {@update3DPointS});
    blabel = uicontrol('Parent',f,'Style','text','string','r',...
      'units','normalized','Position',[0.25,.015,.02,.03]);
    b1 = uicontrol('Parent',f,'Style','slider','units','normalized',...
      'Position', [.5,.005,.5,.01],'value',x, 'min',0, 'max',1, ... 
      'Callback', {@update3DPointS});
    b1label = uicontrol('Parent',f,'Style','text','string','x','units', ...
      'normalized','Position',[0.75,.015,.02,.03]);

Now nest your callback within the main function block as

 function update3DPointS(~,~)
     r = get(b,'Value');
     x = get(b1, 'Value');

     y=sqrt(r^2-x^2);
     z=sqrt(1-x^2-y^2);

     set(s,'XData',x,'YData',y,'ZData',z); 
 end

Now run your code and see what happens. Whenever you press one of the arrows at either end of either slider, then the red dot will update its position. See the attached code for an example.

[David Pesetsky]

When I launch that in 2012a, I get:

   function myScatterSliderTest
   |
   Error: Function definitions are not permitted in this context.

But the sliders do push the red dot around.

To keep the red dot fixed to the sphere surface, I'll need to keep setting the max x limit of the slider controlling x per some equation like x<=r at all times....

Thank you for helping with this.

[Geoff Hayes]

David - am not sure why you are observing that particular error. Did you copy the test file as is, or try to modify it? With my 2014a, there are no error messages.

As for the need to set the max x limit, why would it change?

[David Pesetsky]

Hey Geoff,

Turns our copying code from an html view is a bad idea. I downloaded the attachment instead, and it works fine. Must be hidden characters :)

The issue with x is seen when you have a small r, and increase x all the way, the red point moves off the sphere surface. To keep it confined, I need to continually update the max value of the x slider to be equal to r.

[David Pesetsky]

This seems to work...except when r goes to 0 and the x slider's min=value=max=0, and it complains, and the x slider disappears until the r slider is moved again.

    function update3DPointS(~,~)
        r = get(b,'Value');
        x = get(b1, 'Value');
        if x > r
         set(b1, 'Value', r);
        end
        set(b1, 'max', r);

        y=sqrt(r^2-x^2);
        z=sqrt(1-x^2-y^2);

        set(s,'XData',x,'YData',y,'ZData',z); 
    end

[Geoff Hayes]

David - you probably want to have either a minimum value that r can be (maybe zero doesn't make sense) or a maximum that x can be so that it can't go to zero.

[David Pesetsky]

Yep. That works perfectly now.

    function update3DPointS(~,~)
        r = get(b,'Value');
        x = get(b1, 'Value');
        if r == 0
         r = 0.0001;
         set(b, 'Value', r);
        end
        if x > r
         set(b1, 'Value', r);
        end
        set(b1, 'max', r);

        y=sqrt(r^2-x^2);
        z=sqrt(1-x^2-y^2);

        set(s,'XData',x,'YData',y,'ZData',z); 
    end

Answer 2

[Sameed Quais]

Can anyone of you explain this same question to be solved by using guide instead of using the above call back program?