How can I do a frame-capture style video recording in "Simulink 3D Animation" using matlab?

I'm trying to create video recording of a complicated (30+ nodes) system in "Simulink 3D Animation" that is driven by a matlab script (I don't have simulink). The system is complex enough that I can't simply use the video recording functionality that records what is displayed in the animation viewer because it is too slow and choppy.

Instead, I would prefer to approach the problem similarly to animations in standard matlab plots, in which I use "gcf" to capture the frame, and then when I use "movie2avi" I can dictate the frame rate, such that no matter how long my simulation takes to run each loop, I get an output video with the correct fps.

Alternatively, I'm open to any solution that allows a deterministic selection of frame rate that is not dependent on how fast the computer is able to churn through the model.

[Nathan Fenner]

One correction: I use getframe(gcf) to capture the frame.

Answer 1

[Jan Houska]

To get a single static screenshot of the current Simulink 3D Animation figure, please do

y = capture(vrgcf);

Then, you should be able to create the video stream by using selected screenshots, as needed.

[Nathan Fenner]

Thanks for the help.

I ended up using vr.canvas, and then using getframe(gcf) and that worked pretty well.

I can't get capture(vrgcf) to work.

From a high-level I'm using it as follows:

     for i=1:endIndex
          %update virtual scene
          M(i) = capture(vrgcf);
     end

     movie2avi(M, 'test');

When I do this, I get the error: "Subscripted assignment dimension mismatch."

I'm having trouble finding the documentation for proper use of this function (and basically all documentation associated with "Simulink 3D Animation").

Answer 2

[Jan]

Hi Nathan,

The error message "Subscripted assignment dimension mismatch." comes from the different matrix sizes during the assignment - with (i) subscript the M matrix doesn't get expanded to the assumed size (x,y,i)..

Instead of arranging the matrix M I suggest you to use the VideoWriter object, where you can easily add frames by code like this:

writeVideo(rec_obj, capture(vrgcf))

Best Regards,

Jan

Answer 3

[Angelo Yeo]

MATLAB/Simulink from R2025a supports recording Simulink's 3D Animation with sim3d.io.VideoWriter (MATLAB) or Simulation 3D Video Writer block (Simulink).