For molecular modelers, visualizing conformational changes, docking simulations, or reaction mechanisms using trajectories is part of the daily routine. But what if you need to replay a molecular pathway—accurately—in reverse?
Whether you’re trying to demonstrate molecular unbinding, study pathway reversibility, or simply want a smoother animation for presentations or publications, precise reverse playback of a path is often more than just playing frames backwards. That’s where SAMSON’s Play reverse path animation becomes especially helpful.
Why reverse playback matters
Animations in molecular modeling aren’t just for aesthetics—they’re key to understanding. Reversing a path can help compare forward and reverse mechanisms, illustrate bidirectional transitions, or even emphasize symmetry in molecular conformational changes.
Simply flipping frames in a video editor usually fails: frame timing, transitions, and spatial interpolation often break, especially if the original trajectory was non-linear. The Play reverse path effect in SAMSON handles this more intelligently.
How it works in SAMSON
In SAMSON, each calculated or recorded molecular movement—like a docking trajectory—is stored in a Path node. The Play reverse path animation lets you animate one or more of these paths in reverse between any two keyframes.
Getting started
Here’s what to do:
- First, select the Path node(s) you want to reverse-play. These must already exist in your document.
- Open the Animation panel from the Animator.
- Double-click on Play reverse path in the Animation panel to add it.
- Adjust keyframes to set the playback range.
If you’ve selected multiple paths, SAMSON will synchronize them, which is useful when comparing similar but distinct simulations (e.g., different ligands unbinding from the same pocket).
Customizing the playback
Animations may need to interpolate between uneven frame counts. By default, SAMSON applies smoothing so the reverse animation flows naturally. However, if preserving raw data trajectory is a priority (e.g., for quantitative analysis), smoothing can be turned off in the Inspector.
Interpolation can be customized using an Easing curve, allowing finer control over motion speed and acceleration. For example, you might slow down reverse motion near a transition state to highlight its features.
A note on keyframes
You are free to move the keyframes anytime. This flexibility allows you to tightly control when the reversed playback starts and stops as part of larger animations or presentations.
Best use cases
- Visualizing molecule unbinding sequences
- Comparing conformational changes forward and backward
- Creating cyclic animations (combine with “Play path”)
- Demonstrating symmetry or reversible diffusion processes
By integrating reverse animations smoothly into modeling workflows, you can boost the clarity and explanatory value of your scientific communication—whether it’s for colleagues, publication reviewers, or students.
To learn more, please visit the official documentation page.
SAMSON and all SAMSON Extensions are free for non-commercial use. You can download the platform at www.samson-connect.net.