Animation

Animation(compute=None, reset=None, view=None)

Minimal base class for time-stepped animations.

Animation defines the three lifecycle hooks that the [Engine][npblender.engine.Engine] calls on every frame/subframe: reset(), compute(), and view(). You can either subclass and override these methods, or pass callables to the constructor to set _reset, _compute, and _view dynamically. It also exposes lightweight accessors to the global engine (engine, time, delta_time) and optional baking hooks.

Notes

• reset() is called once on the first frame of a run.
• compute() is called at each substep; the engine enumerates subframes as 1, 2, …, n-1, 0, where 0 is the main frame after substeps.
• view() is called after compute/load to push results into Blender.

Optionally provide function-based hooks instead of subclassing.

If a callable is provided, it is bound to the corresponding private attribute (_compute, _reset, _view) that compute(), reset(), and view() will delegate to.

Parameters:

Name	Type	Description	Default
compute	callable or None	Step function called at each subframe.	None
reset	callable or None	Initialization function called at the first frame.	None
view	callable or None	Function that writes results back to Blender.	None

delta_time property

delta_time

Time step between substeps (proxy to engine.delta_time).

Returns:

Type	Description
float	time_scale / fps / (subframes + 1).

engine property

engine

Global engine singleton.

Returns:

Type	Description
Engine	The module-level engine instance that drives the animation.

time property

time

Current time in seconds (proxy to engine.time).

Returns:

Type	Description
float	The timeline time including subframes, offset, and scale.

compute

compute()

Per-substep compute hook.

To be overridden

Delegates to _compute() if defined. Called by the engine for each subframe and the main frame (… , n-1, 0).

get_frame_data

get_frame_data()

Return animation data to be baked for the current frame.

Returns:

Type	Description
Any or None	Per-animation payload to store in the bake file, or None to skip.

get_frame_state

get_frame_state()

Return state to be saved to resume simulation from the current frame..

Returns:

Type	Description
Any or None	Optional state payload

go

go(subframes=0)

Run this animation once through the engine.

Convenience wrapper for engine.animation(self, subframes=subframes).

Parameters:

Name	Type	Description	Default
subframes	int	Number of subframes per frame.	0

Examples:

anim = Animation(compute=lambda: ..., reset=lambda: ..., view=lambda: ...)
anim.go(subframes=4)

reset

reset()

First-frame initialization hook.

To be overridden

Delegates to _reset() if defined. Called once by the engine at the first frame of the run.

set_frame_data

set_frame_data(data)

Load animation data from the bake file for the current frame.

Parameters:

Name	Type	Description	Default
data	Any	Payload previously produced by get_frame_data().	required

Returns:

Type	Description
bool	True if the data was applied successfully, else False.

set_frame_state

set_frame_state(data)

Restore persistent state saved with the current frame.

The simulation can be resume for next frames.

Parameters:

Name	Type	Description	Default
data	Any	State payload previously produced by get_frame_state(). :contentReference[oaicite:13]{index=13}	required

view

view()

Push results into Blender.

To be overridden

Delegates to _view() if defined. Called by the engine after compute or after loading a baked frame, to update Blender data/objects.