When analyzing molecular structures and motions, it’s often helpful to step back—literally. While forward trajectories offer valuable insights, playing molecular paths in reverse can highlight subtle interactions, simplify comparisons, or illustrate transitions between conformations more clearly. This is especially useful when preparing animations for communication or teaching purposes.
In SAMSON, the Play reverse path animation effect offers a straightforward way to reverse the playback of one or several molecular paths. This feature is part of SAMSON’s animation toolkit, and it allows users to retrace the motion of a molecule over time—automatically and with visual continuity. Here’s how it works and why it might be the piece you didn’t know you were missing.
Why reverse animations matter
For molecular modelers, being able to visualize structural transitions can help with:
- Revealing reversible molecular processes
- Debugging simulation trajectories by identifying mismatches
- Creating clear visualizations of cyclic motions
- Communicating kinetic concepts in lectures
Forward motions are usually available by default. But to play a structure’s path in reverse, you’d otherwise need to duplicate and manually rekey the motion path—potentially a tedious process. With SAMSON’s built-in support for reverse animations, you can automate this task immediately.
How to add the Play reverse path animation
To begin, first identify the Path node associated with your trajectory. This node stores the structural changes of your molecule between two keyframes (e.g., a reaction coordinate over time).
Then:
- Open the Animation panel in the Animator.
- Double-click on the Play reverse path animation effect.
- The path will now be played backward between the selected keyframes. You can move or adjust these keyframes to control timing.
Whether you select one or several paths, the animation will attempt to synchronize them. This means you can reverse complex multi-part molecular assemblies without losing temporal alignment.
Smoothing, easing, and controls
By default, if there’s a mismatch between the number of frames in your animation and those stored in the path, the transition will be smoothed—helping preserve visual continuity. If needed, this smoothing can be turned off directly in the Inspector.
It’s also possible to adjust how parameter transitions are interpolated. In the Inspector, you’ll find the Easing curve settings. These allow you to control acceleration or deceleration between frames and fine-tune the pacing of the animation.
Examples and visuals
Here’s what it looks like when a molecular path is played in reverse using this feature:
These options provide a low-friction way to build reversible animations, either for analysis or for generating visual material. You can continually modify keyframes and replay to adjust as your story evolves.
Learn more in the full documentation here:
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.