Analyzing molecular simulations often means reviewing complex motions over many frames of a trajectory. For modelers studying folding patterns, automated docking, or multistep reactions, reviewing these paths backward can reveal behavior that is missed in typical forward playback. If you’ve ever scrolled frame-by-frame just to analyze a transition in reverse, there’s a better way—use the Play reverse path animation in SAMSON.
Why Reverse Playback?
Playing a trajectory backward is not just about convenience. It’s especially useful for:
- Visualizing the dissociation of a ligand from a receptor after binding
- Understanding unbinding pathways and escape dynamics
- Demonstrating reversible transitions between conformational states
- Creating visually engaging presentations by showing transition cycles
If multiple paths are involved, Play reverse path synchronizes their playback, which is key when analyzing multicomponent systems.
How to Use It
Start by selecting one or more paths you’d like to animate in reverse. These paths represent stored trajectories, typically created through simulations or manual manipulation inside SAMSON.
Then, open the Animation panel via the Animator. Double-click the Play reverse path animation. SAMSON immediately generates an animation that plays the full path in reverse, between two keyframes.
You can adjust the timing of the animation by moving the keyframes on the timeline. The motion is smooth by default, interpolating frames if the animation’s duration does not match the number of path frames. If you need precise, raw frame playback for exact reproduction, you can disable this smoothing in the Inspector.
Smoothing and Easing Options
Often, a molecular path does not exactly match your target animation’s length. Rather than skip or stall frames, SAMSON smooths the trajectory using interpolation. While this is usually beneficial—especially for presentations—you may wish to switch this behavior off while analyzing raw data.
Interpolation settings can be found in the Inspector panel, where you can also adjust the easing curve. Choosing a different easing curve lets you refine how the motion accelerates or decelerates across the animation span.
An Example in Action
The animation below demonstrates how a reverse path can replay a trajectory backward. This is valuable not just for analysis but also for scientific communication, helping highlight reversible transitions or suggest potential mechanisms for molecular events.
Conclusion
You don’t need to manually rewind molecular paths frame by frame. With SAMSON’s Play reverse path animation, you get a practical, visual tool to trace, communicate, and hypothesize molecular mechanisms by looking at them from the other side.
Explore more about this feature in the official documentation.
SAMSON and all SAMSON Extensions are free for non-commercial use. You can download SAMSON here.