While compositing, RenderLayer doesn't move with time I tracked a sequence of images and want to add a box to the tracked scene.
All works well, and in the 3D view, if I change the current frame, the box looks aligned to
the movie, which I use as a background.

When compositing, I have a RenderLayer node and the movie node combined using "over alpha". This works, but in the viewer, the rendered cube is at a fixed location (doesn't move with the scene), as it it's pinned to a single frame. The 3D view still works, and as I slide the current time, the cube moves with the movie.

Any suggestions?

Attaching a screenshot where the cube is aligned (next to the mouse) in the 3D view (bottom right), but not in the composite viewer (bottom left).



To make things more clear, here's a comparison of the 3D view (on the right) and the composite result view (on the left). First, on frame 20:



Now on frame 50:



And finally on frame 220:



In the composite output view, the cube is stationary while in the 3D view it's "moving" with the tracked camera.

Here's the blend file: comp_room2.blend
You have to rerender each frame in order to update the comp. You can do this by pressing F12 to render the whole scene or clicking the render icon on the layer node to render just that layer.



It would be simple to add the possibility of rerendering when the frame is changed, but in reality most renders take several minutes (sometimes hours, or days) to render and thus accidentally changing the frame would clear the render and you would have to wait for it to finish again.

Of course this option could be disabled by default, but I don't see any serious use coming from this and thus it's not worth the effort to code.