A moving molecular trajectory can be difficult to follow when the region you care about drifts toward the edge of the view. Repositioning the camera by hand may help for a moment, but it can also change the framing you wanted to preserve. The Look at atoms animation addresses this specific problem: it keeps the camera aimed at a selected group of atoms while leaving the camera’s position unchanged.
This is useful when you want to watch a particular part of a system as the structure changes—for example, to keep a selected region in view while viewing a trajectory. Rather than moving the camera through space, the animation moves its target point. The camera continues to look from the same position, while its target follows the geometric center of the selected atoms between the animation’s keyframes.
Set up the view before adding the animation
Start by selecting the atoms that should remain the focus. Then orient the view so the camera is in the position you want. This order matters: the animation uses the atoms selected when it is created, and the camera’s current position is used for its start and end frames.
- Select the atoms you want the camera to look at.
- Move or orient the view to establish the camera position you want to keep.
- In the Animator’s Track view, choose the animation’s start frame.
- In the Animator’s Animation panel, double-click Look at atoms.
- Set the end frame to cover the part of the trajectory you want to view.
The start and end frames can be moved later, so you can adjust when the camera-following behavior begins and ends without rebuilding the whole animation.
What moves—and what stays fixed?
The key distinction is between the camera’s target and its position. During the animation, the target follows the geometric center of the specified atoms. The camera position does not change as a result of this animation. That makes Look at atoms a good choice when you want to retain a consistent viewing position but keep a moving region centered in the view.
If you need to change the camera position, you can adjust it with the animation controllers. The target remains at the geometric center of the specified atoms. In other words, adjusting the viewing position does not change which atoms define the focus.
Check the camera settings if the result differs
By default, camera animations apply to the active camera. If you need a different camera, inspect the animation and change Apply to active camera. The animation’s target point is defined using the active camera’s current target position, which is essentially the center of the current view.
The grid can also affect how camera positions are defined. If the camera behavior differs depending on whether the grid is visible, inspect the animation’s Keep camera upwards option. When checked, the behavior depends on whether the grid is on or off. This setting is worth checking when you are comparing views made with different grid states.
Look at atoms is therefore most helpful when the goal is simple: preserve the camera’s position, but keep a selected moving part of the molecular system in view. If you are considering a different camera-following behavior, SAMSON also documents a related Follow atoms animation.
For the complete instructions and animation properties, see the Look at atoms documentation.
Note: SAMSON and all SAMSON Extensions are free for non-commercial use. Get SAMSON.