When exploring molecular dynamics simulations or visualizing conformational rearrangements, it’s often just as important to go backward as it is to go forward. Whether you’re presenting your work or trying to better understand a transition, being able to rewind animations smoothly can help reveal patterns you might otherwise miss.
In SAMSON, the reverse playback of a molecular trajectory is handled by the Play reverse path animation. Let’s look closer at how this feature solves a common visualization challenge and lets you control the structure’s time-evolution in reverse.
Why reverse playback matters
Researchers frequently analyze forward simulations to observe how systems evolve, but the reverse perspective is invaluable in several scenarios:
- Identifying how a ligand re-enters or exits a binding pocket
- Observing the return to a folded state in protein simulations
- Creating looping animations for presentations or educational content
In many tools, reverse playback isn’t easily accessible or may require re-generating new trajectories. SAMSON avoids this by providing a dedicated animation effect.
How it works
To use the reverse animation effect in SAMSON:
- Load or generate a Path node, which contains the trajectory you want to rewind.
- Open the Animator and go to the Animation panel.
- Double-click on Play reverse path.
- Adjust the keyframes on the timeline as needed. The path will play backwards between these frames.
You can also play multiple paths in sync by applying the animation to more than one Path node. For example, you could simultaneously rewind the movements of multiple molecules or chains.
Customization and smoothing
One useful feature is that the system smoothly interpolates between frames when the number of animation frames differs from the number of trajectory frames. This creates visually continuous paths, even for short animations. If you prefer to match the original frames exactly, smoothing can be turned off in the Inspector.
You can further control the pace of the animation by editing the Easing curve. For instance, using a slow-in, slow-out curve can help emphasize the motion’s start and end phases.
Practical tips
- Cycle through conformations: Use forward and reverse playback effects to create a loop between structural states.
- Highlight return paths: Temporarily hide forward motion and isolate reverse playback to draw focus to re-folding or recombination events.
- Combine animations: Use reverse playback with other effects (camera transitions, annotations) for clear visual storytelling.
Here’s what the result can look like:
Conclusion
The Play reverse path animation in SAMSON is a simple but helpful tool that lets modelers and educators analyze or present molecular motion from a new angle. By reversing your trajectory playback, you can better explore how and why your systems follow certain paths.
To learn more, visit the full documentation page on this topic: https://documentation.samson-connect.net/users/latest/animations/play-reverse-path/
SAMSON and all SAMSON Extensions are free for non-commercial use. You can download SAMSON at https://www.samson-connect.net.