Focus

Animate the camera to a protein or selected region.

View source Guide and examplesInherits Animation

from proteinmotion import Focus

Constructor

Focus(
    camera,
    region,
    *,
    margin=1.25,
    aspect=None,
    follow=True,
    screen_position=(0.5, 0.5),
    **kwargs,
)

Parameters

Parameter	Default	Description
`camera`	Required	Camera used to project or frame objects.
`region`	Required	Region selection attached to a protein.
`margin`keyword only	`1.25`	Positive framing margin; larger values leave more space around the target.
`aspect`keyword only	`None`	Image width divided by height.
`follow`keyword only	`True`	Track the selection’s center after the focus completes.
`screen_position`keyword only	`(0.5, 0.5)`	Normalized subject position; (0, 0) is top-left and (1, 1) bottom-right.
`**kwargs`	—	Additional keyword options described below or in the linked constructor.

Additional keyword arguments

Parameter	Default	Description
`rate_func`keyword only	`smooth`	Callable that maps progress in [0, 1] to a finite value in [0, 1].

Notes

Evaluated after molecular movement in the same play() call. follow=True keeps tracking the region center after the focus finishes.

Example and output

This excerpt runs inside a scene’s construct() method. The full example file includes imports, structure loading, and camera setup. Run it from a repository checkout.

Code Scene excerpt

p = ubiquitin()
frame(self, p)
helix = p.select(chain="A", residues=(23, 34))
marker = helix.highlight(
    style="box",
    color="#f2ba67",
    padding=1.5,
)
self.play(FadeIn(marker), run_time=0.6)
self.focus(helix, margin=1.6, run_time=1.5)
self.play(self.camera.animate.orbit(0.4), run_time=2)
self.play(FadeOut(marker), run_time=0.6)
self.focus(p, run_time=1.5)

Output Preview · 6.2 s · 60 fps

Camera focus

Ubiquitin residues 23–34.

Full source: RegionFocus Download MP4

Methods and properties

Name	Description
bind()method	Capture starting values when the scene schedules the animation.
apply()method	Evaluate the animation at eased progress alpha. Called by the timeline.
during()method · inherited from Animation	Set this animation duration and start delay in seconds.
targetsproperty · inherited from Animation	Objects whose state this animation changes.