unable to adjust real time views of surf plots in plot-drawnow animations

In plot-drawnow animations, how to use the mouse to adjust the view of a 3d surf plot? I've found that there's no response to any real time mouse adjustment and the view stays unchanged.

[Vinayak]

Hi feynman,

I tried to reproduce with a simple sample code, but was not able to. Here is a sample code that you may refer to while updating the surf plots, make sure to update all values (X, Y and Z) in case there is a change in dimensions. Also, you may like to add a small pause to control the refresh rate.

fig = figure
ax = axes;
[X, Y] = meshgrid(-2:0.1:2, -2:0.1:2);
Z = sin(X) .* cos(Y);
surf_plot = surf(ax, X, Y, Z);

while ishandle(fig)
    % Update data
    t = rand*5;
    [X, Y] = meshgrid(-1*t:0.1:t, -1*t:0.1:t);
    Z = sin(X) .* cos(Y);
    set(surf_plot, 'XData', X, 'YData', Y, 'ZData', Z);
    drawnow;
    pause(0.01);
end

If you would like to know more on `set`, refer to the documentation:

https://www.mathworks.com/help/matlab/ref/set.html

If this doesn’t help, please share a sample code.

[feynman feynman]

excellent thank you! set really helps do this!

I have in the while loop multiple plots on the same graph with surf, plot3. In that case, I find it hard to hold on/off and adjust the view at the same time.

fig = figure
ax = axes;
[x, y] = meshgrid(-2:0.1:2, -2:0.1:2);
z = sin(x) .* cos(y);
surf_plot = surf(ax, x, y, z);hold on
while ishandle(fig)
    surf(x,y,z)
    plot3(linspace(0,1),linspace(0,1),linspace(0,1)+rand)
    % Update data
    t = rand*5;
    [X, Y] = meshgrid(-1*t:0.1:t, -1*t:0.1:t);
    Z = sin(X) .* cos(Y);
    set(surf_plot, 'XData', X, 'YData', Y, 'ZData', Z);
    pause(0.1);hold off
end

[Vinayak]

Hi Feynman

The "hold off" in the end of while loop may overwrite the figure handle, this results in an invalid/deleted object for me.

Relocating it outside the while loop resolves the issue and the graph works as intended.

clear; 
fig = figure 
ax = axes; 
[x, y] = meshgrid(-2:0.1:2, -2:0.1:2); 
z = sin(x) .* cos(y); 
surf_plot = surf(ax, x, y, z); 

hold on 
rotate3d on % Enables rotate3d mouse action 

while ishandle(fig) 
    % surf(x,y,z) 
    % Update one plot3 graph 
    if ~exist('lx','var') 
        lx = plot3(linspace(0,1),linspace(0,1),linspace(0,1)+rand); 
    else 
        set(lx, "XData", linspace(0,1), 'YData', linspace(0,1), 'ZData', linspace(0,1)+rand); 
    end 
    
    % Add more plot3 on every loop run 
    % plot3(linspace(0,1),linspace(0,1),linspace(0,1)+rand); 
    
    % Update data 
    t = rand*5; 
    [X, Y] = meshgrid(-1*t:0.1:t, -1*t:0.1:t); 
    Z = sin(X) .* cos(Y); 
    set(surf_plot, 'XData', X, 'YData', Y, 'ZData', Z); 
    pause(0.1); 
end 

hold off 

[feynman feynman]

thank you so much for resolving this @Vinayak this is the best answer!

[feynman feynman]

a followup question, rotate3d on doesn't seem to play well in live scripts when figures aren't shown in a separate file! Once rotate3d on, animations disappear but only the final screenshot is retained. Any solution?

Answer 1

[Benjamin Kraus]

@Vinayak has the right idea, although pause should be unnecessary and drawnow is definitely the preferred approach.

• drawnow will guarantee that the graphics are drawn and MATLAB responds to any user interactions or callbacks that occured during your loop.
• pause will pause execution for a moment which may give graphics a chance to update, and may respond to callbacks, but if MATLAB has't finished drawing or responding to callbacks before the time expires, it does not guarantee that these things occur.

You can use both pause and drawnow if you want to both guarantee that each frame draws, but also slow down the loop if it is running too quickly.

[feynman feynman]

Thanks a lot! A followup question, rotate3d on doesn't seem to play well in live scripts when figures aren't shown in a separate file! Once rotate3d on, animations disappear but only the final screenshot is retained. Any solution?