Creating meaningful molecular animations often means more than just showing atoms and bonds moving – it’s about telling a story of how molecules react, interact, and change over time. But what happens when you want to reverse that story? Whether you’re analyzing a folding/unfolding event, returning to an initial conformation, or looping through states in a reverse direction, easily creating reversed animations of a trajectory can save you time and effort.
This is where the Play reverse path animation in SAMSON becomes useful. Rather than having to create a new reversed trajectory or manually shuffle frames, this simple tool helps you visualize a molecular path in reverse between any two keyframes.
When and why should you play a trajectory in reverse?
Reverse animations can be useful in several scenarios:
- To analyze the unfolding process by rewinding a folding pathway
- To inspect reversibility in a molecular simulation
- To alternate between two conformations cyclically
- To emphasize before/after structural changes in presentations
These visual cues are not just presentation flourishes—they help communicate complex molecular mechanisms more clearly, both to experts and non-specialists.
How it works
Once you have a Path in your SAMSON document (usually created using trajectory data or movements between conformations), adding the reverse animation is straightforward:
- Select the path(s) you want to animate.
- Double-click the Play reverse path effect from the Animation panel within the Animator.
- Two keyframes are created automatically. The entire path is played in reverse between these frames.
- You can freely reposition the keyframes to define the exact timing of the reverse play.
The animation is also synchronized if you have selected multiple paths together. This is particularly helpful for comparing or coordinating conformational changes across different molecules or domains.
Fine-tuning with easing curves
Animations don’t have to be linear. With the Easing curve options in the Inspector panel, you can control how the parameters change between keyframes. This includes acceleration, deceleration, or adding a bounce effect, helping emphasize specific structural transitions.
Also, don’t forget to explore your preferences for smoothing the motion path. If the frame count between your animation and your recorded path differs, SAMSON will smooth out the motion automatically—but you can disable this in the Inspector for a more rigid representation.
Visual example
The following example illustrates a path being played in reverse inside the SAMSON Animator:
To learn more and explore the full details, visit the Play reverse path documentation page.
SAMSON and all SAMSON Extensions are free for non-commercial use. You can download SAMSON at www.samson-connect.net.