🍰 Baking Animation

After a successful Fetch All Animation the solver’s output drives each simulated object through a ContactSolverCache modifier (meshes) or per-CV keyframes written directly on the curve (rods). That is perfect while you iterate on a shot, but it keeps every object tied to the add-on: the animation depends on the .pc2 files on disk, the modifier on the mesh, and the group membership in the sidebar.

Baking converts that fetched animation into standard Blender data: per-frame shape keys for meshes, per-control-point keyframes for curves. After a bake, the ContactSolverCache modifier is dropped, the object leaves its dynamics group, and the animation is self-contained Blender data that plays back in any scene, with or without the add-on installed.

There are two flavors:

• Bake Animation. Keyframes every fetched frame onto the object. Use this when you are done iterating and want to hand the scene off.

• Bake Single Frame. Captures the current frame’s pose only and freezes the object there as Frame 1. Use this to turn a cloth-draping step into the rest pose of the next simulation, or to freeze a pin operation’s final shape.

What the object looks like before and after Bake Animation. Everything on the left that is orange (modifier), mauve (pin vertex groups), or yellow (group membership) is the add-on’s; baking removes those and the PC2 file on disk that backs the modifier. What remains on the right (green) is the object’s own Blender data: per-frame shape keys plus the fcurves that drive them. The red arrow only goes one way.

Note

Baking requires simulation data to exist for the object. Run the Transfer → Run → Fetch All Animation loop (see Running the Simulation) first; the bake buttons are grayed out until there is fetched animation to bake from.

Baking Is Destructive: Duplicate the .blend First

Once a bake finalizes, it cannot be undone from the UI. For every baked object the add-on:

• removes the ContactSolverCache modifier from the mesh (or drops the per-CV animation the solver wrote onto the curve for rods),

• deletes the .pc2 file from <blend_dir>/data/<basename>/ on disk, and

• removes the object from its dynamics group, together with any pin vertex groups attached to it.

Recommended workflow: always bake in a copy of your .blend, so the pre-bake scene (with its PC2 files, modifiers, and group setup) stays intact as a fallback.

1. Save the current .blend (File → Save).

2. Duplicate the .blend on disk, outside Blender. Run cp project.blend project_baked.blend in a terminal, or copy the file in Finder / Explorer. Do not use File → Save As from the currently-open session; the PC2 files need to stay paired with the original .blend.

3. Open the duplicate. The Solver panel detects that the ContactSolverCache modifiers still point at <blend_dir>/data/<old_basename>/ while the new .blend’s canonical data folder is <blend_dir>/data/<new_basename>/, and surfaces a migration prompt:

   

   The Solver panel in a freshly-opened duplicate. The error line (Data path: …/data/project_baked/…pc2 does not exist.) flags the missing canonical PC2 data, the Migrate data/project/ → data/project_baked/ button migrates in one click, and the Missing files (N) list underneath enumerates every PC2 that would need to be moved.

4. Click Migrate. A dialog appears with From / To folders and a Keep Copy checkbox (checked by default). Leave Keep Copy on; the operator then shutil.copytrees data/<old>/ → data/<new>/ and rewrites every ContactSolverCache modifier filepath to point at the new folder. The original data/<old>/ stays untouched, so the source .blend keeps working.

5. Save the duplicate once more so the rewritten modifier filepaths are persisted.

6. Bake in the duplicate. The PC2 files that get deleted belong to data/<new_basename>/; the original .blend’s data/<old_basename>/ is preserved.

Tip

Unchecking Keep Copy switches the migration from shutil.copytree to os.rename, saving disk space at the cost of leaving the original .blend pointing at a folder that no longer exists. Only turn it off when you are certain you want to abandon the source .blend.

Warning

The migration button only appears when the mismatch is unambiguous: every ContactSolverCache modifier points into a single data/<old>/ folder, and that folder is still on disk. Mixed prefixes or a missing source folder return no migration target, and the Solver panel shows only the missing-file warning. In that case the cleanest recovery is to manually copy data/<old>/ → data/<new>/ with the file manager / cp -r, then reopen the .blend.

The Solver Panel (Bake All Objects)

The Solver panel exposes a row that bakes every dynamic object in the scene in one go. The buttons sit directly under Fetch All Animation and Delete Remote Data:

The scene-wide bake row on the Solver panel. Bake Animation (left) writes every fetched frame onto every simulated object as shape-key or curve keyframes; Bake Single Frame (right) freezes the current frame onto every simulated object as their new Frame 1.

Bake Animation runs as a modal job with a progress bar. The panel shows a live Baking <object> [N/total] status line and an Abort button while frames are keyframed. Abort restores every modifier / shape key / fcurve to its pre-bake state.

Bake Single Frame is synchronous and finishes in one click. Every dynamic object is frozen at the viewport’s current evaluated pose, applied to frame 1, and removed from its group.

Both scene-wide buttons are enabled only when at least one active group has an assigned object carrying simulation animation (that is, only after a successful Fetch). While a bake job is running every other button on the Solver panel is inert; wait for the progress bar to finish or press Abort.

The Dynamics Groups Panel (Bake One Object)

Each group box has its own Bake Animation / Bake Single Frame row, sitting below the Add Selected Objects / Remove Object row. These bake only the object currently selected in the group’s list, not the whole group or the whole scene:

The per-group bake row on each Dynamics Groups box. The two buttons are enabled when the row highlighted in the assigned-object list has fetched animation. The baked object leaves the group (so it won’t be re-simulated on the next Transfer) but keeps its keyframes.

Per-object Bake Animation uses the same modal progress + Abort flow as the scene-wide version, so the panel stays interactive for the other groups while one object bakes.

What Ends Up on the Object

The output format depends on the object type:

Object type	What gets keyed	Modifier removed
Mesh	One shape key per fetched frame, named ContactSolverBake_NNNNN, each driven 0 to 1 to 0 with CONSTANT interpolation so exactly one key is active per frame.	ContactSolverCache
Curve	Per-control-point keyframes on co / handle_left / handle_right (bezier) or on co (poly / NURBS).	ContactSolverCache (curves keep the baked rest pose)

After baking, the object:

• No longer appears in its Dynamics Groups slot; the assignment is cleared, together with any pin vertex groups attached to it.

• Still plays back its simulated motion in Blender’s timeline, because the animation now lives in shape keys / fcurves on the object itself.

• Can be moved, duplicated, appended to other .blend files, or rendered on a render farm without shipping the .pc2 file.

Warning

For meshes, Bake Animation adds one shape key per frame. The add-on refuses to bake a mesh that already carries non-Basis shape keys, because mixing baked keys with user-authored ones would double-blend. Remove extras manually (shape-keys panel, then trash icon) before baking.

Aborting a Bake

Bake Animation runs modally. While the bake is in progress the Solver panel shows:

• A status line (Baking <object> [N/total]) updating as frames are keyed.

• A progress bar (% (done/total)).

• An Abort button (red “X” icon).

Pressing Abort reverts every partial change: shape keys inserted so far are removed, their value fcurves are stripped, bezier handle types are restored, and the ContactSolverCache modifier + PC2 file stay intact, so you can immediately press Bake Animation again or go back to iterating.

Bake Single Frame does not run modally and cannot be aborted; it finishes in one operator call.

Bake Order and Static Groups

Bake Animation walks through active groups in slot order (object_group_0 → object_group_31) and bakes every assigned object. Static groups are included so their ContactSolverCache modifier and PC2 file get cleaned up too, leaving every bakeable group empty once the scene-wide bake finishes. See Static Objects → Baking behavior for the full story on what bake does to a Static object depending on whether it was driven by Blender keyframes or by Static ops.

Groups that hold curves alongside meshes bake both: meshes emit shape keys, curves emit per-CV keyframes, and both end up on standard Blender timelines.

Blender Python API

Baking is exposed through the add-on’s registered operators:

import bpy

# Scene-wide: bake every dynamic object.
bpy.ops.solver.bake_all_animation()          # modal; returns immediately
bpy.ops.solver.bake_all_single_frame()       # synchronous

# Per-object, per-group (group_index is the slot 0..31).
bpy.ops.object.bake_animation(group_index=0)
bpy.ops.object.bake_single_frame(group_index=0)

# Abort the running bake (no-op if none is running).
bpy.ops.solver.bake_abort()

For LLM / MCP-driven flows, the same actions are exposed as the scene.bake_all_animation, scene.bake_all_single_frame, group.bake_group_animation, and group.bake_group_single_frame handlers (see MCP Integration).

Under the hood

Operator names

Button	bl_idname
Solver panel → Bake Animation	solver.bake_all_animation
Solver panel → Bake Single Frame	solver.bake_all_single_frame
Dynamics Groups → Bake Animation	object.bake_animation
Dynamics Groups → Bake Single Frame	object.bake_single_frame
In-progress bake → Abort	solver.bake_abort

Shape key naming

Baked mesh shape keys are named ContactSolverBake_<frame:05d>. The value channel for each key is driven with three keyframes (0 at frame-1, 1 at frame, 0 at frame+1), and every keyframe is forced to CONSTANT interpolation so frame N plays exactly one shape key, with no blending.

Abort safety

The modal operator snapshots enough state before it starts that an abort is non-destructive:

• For meshes: the pre-existing set of shape-key names and whether the shape-key block existed at all. Abort removes only the keys the bake added, and deletes the shape-key block if the bake created it.

• For curves: the pre-existing set of (data_path, array_index) fcurve keys and the per-spline (handle_left_type, handle_right_type) snapshot. Abort removes fcurves that didn’t exist before and restores bezier handle types that were forced to FREE during the bake.

The ContactSolverCache modifier and the .pc2 file on disk are never touched by an abort, so the pre-bake state is fully recoverable.