When visualizing molecular dynamics simulations or comparing conformational pathways, it’s often useful to view both forward and reverse directions of a molecular journey. If you’re using SAMSON, the Play reverse path animation offers a simple yet effective way to achieve that without duplicating trajectory data or manually reordering frames.
This feature addresses a common pain for molecular modelers: analyzing reversible transitions, understanding alternate conformational states, or checking the repeatability and smoothness of a simulation. Sometimes, a process looks plausible when moving forward, but subtle errors or discontinuities are exposed when played backward. Reversing the path can help scientists assess symmetry and physical realism more effectively.
How it works
In SAMSON, a Path node stores a series of frames—typically representing a trajectory or a transition between molecular conformations. The Play reverse path animation plays this information in the opposite direction, from the last frame to the first. If multiple paths are selected, the animation system synchronizes them automatically for a unified reverse playback.
Getting started
To use Play reverse path, follow these steps:
- Select the path or paths you want to reverse.
- In the Animation panel of the Animator, double-click on the Play reverse path animation effect.
- By default, the entire path will be played between two keyframes, in reverse.
- You can always move these keyframes to adjust the timing.
This feature is particularly helpful in educational videos, where viewers can appreciate reversible motion paths more intuitively, or when you’re preparing presentations that explore the dynamics of systems like protein folding, channel opening, or ligand binding/unbinding events.
Tuning the animation
If the number of frames in the animation duration differs from the number of frames in the path, SAMSON will automatically smooth the motion using interpolation. For more control, this smoothing can be disabled in the Inspector.
Additionally, you can refine how the animation behaves between keyframes by adjusting the easing curve. This determines whether the transition is linear, slow-in-slow-out, or follows another interpolation pattern, giving you finer control over visual pacing.
When to use it
Use Play reverse path when:
- You want to show a reversible molecular process (e.g., folding ↔ unfolding).
- You’re reviewing whether a trajectory looks physically reasonable in both directions.
- You’re presenting a switching mechanism and want to show it toggling between states.
- You’re comparing experimental data with a theoretical model’s behavior in both time directions.
Want details or step-by-step visuals? Visit the official documentation for more information.
SAMSON and all SAMSON Extensions are free for non-commercial use. You can download SAMSON at https://www.samson-connect.net.