The VAT Baker panel

Window ▸ Tools ▸ Ternary Labs ▸ VAT Baker

You can also right-click any baked VAT data asset in the Content Browser and choose Re-bake in VAT Baker — the panel opens with every setting restored from that bake.

Bake parameters

Animation Type

Which kind of source you're baking. See Bake types. Changing it reshapes the panel: the Soft Body (Anim Sequence) entry swaps the actor controls for asset pickers, and some types offer fewer texture precisions.

Source

For most types — select your actors in the level and click Use Selected. Clear empties the list. Rigid Body accepts several actors; every other type takes exactly one, and the panel trims the selection with a note in the log if you select more.

For Soft Body (Anim Sequence) — two asset pickers instead: Skeletal Mesh and Anim Sequence. No level actor is involved.

Start Frame / End Frame

The inclusive frame range to bake.

For Soft Body (Anim Sequence), this is a true range — Start Frame seeks into the sequence, and picking a sequence fills both fields in from its length.

For the simulated types, capture begins when the play session starts, so Start Frame sets how many frames are recorded rather than skipping into the simulation.

Capture FPS

Frames captured per second of simulation time. During a simulated bake the engine is driven at exactly this rate so the capture is even regardless of editor performance.

Frame Step

Bake every Nth frame (1 = all frames). Higher = fewer baked frames / smaller textures; the material interpolates between them.

The simulation still advances at Capture FPS; only every Nth frame is stored. Playback duration is unchanged.

Seamless loop

Controls what the last frame blends into. Playback always loops either way — this decides whether the final frame interval interpolates back toward frame 0, or holds still on the last frame.

On	For a cycle — a walk, a flag, flapping cloth. Without it the final frame freezes, giving a visible hitch once per loop.
Off	For a one-shot sim — a shatter, a splash, anything with an end state. With it on, the settled debris smoothly morphs back into the intact object every loop.

This is a playback setting, not an encoding one. It is written to the data asset at bake time and stays editable there (VAT ▸ Playback ▸ Seamless Loop) — changing it recompiles the material but never requires a re-bake. Re-baking picks up whatever the asset currently has, so a change you make afterwards is not undone.

Output files parameters

Output Path

Content Browser folder for the generated assets, e.g. /Game/VAT/.

Asset Name

Base name for everything the bake produces. See What a bake produces.

Texture Precision

Option	Notes
24-bit (RGBA8)	Smallest. Available for Rigid Body and both Soft Body types.
64-bit (RGBA16F)	Default for Particle and Fluid.
128-bit (RGBA32F)	Largest and most precise.

Particle and Fluid don't offer the 24-bit option. Start at the default; move up only if you see artefacts.

Nanite output mesh

Builds the playback mesh as a Nanite mesh.

This has to be chosen here

You cannot enable Nanite on the mesh afterwards. Nanite interpolates UVs when it simplifies, and the VAT stores a per-vertex index in UV1 — an interpolated index points at the wrong data, so playback breaks. The baker turns that interpolation off; the static mesh editor's Nanite checkbox does not, and gives you no reason to think it should.

Nanite playback also needs Evaluate World Position Offset enabled on the placed component, and be aware of the WPO disable distance, which can switch the animation off at range.

Greyed out for Particle, which plays through a Niagara emitter and produces no mesh, and for Fluid, whose container mesh rests with every triangle collapsed to a single point and addressed by a per-slot index — Nanite's simplification would discard both.

Power-of-two texture size (width + height)

Off (default): the height is exactly the rows needed, wasting under one row. On: both dimensions are a power of two, which can waste up to ~50% of the texture. Use it only if you need block-compressed output (e.g. BC6H), which requires multiple-of-4 dimensions.

Leave off unless you specifically need it.

Generate debug report (.md)

Writes <AssetName>_Debug.md next to the generated assets, recording the settings used, the texture dimensions, and per-unit sample data.

Useful when a bake doesn't look right, and the first thing to attach to a support request.

Baking

Simulated types are captured with Simulate In Editor — the simulation runs with no player pawn or possession, which is what Chaos, cloth, Niagara and Geometry Cache sources need. There is nothing to configure: a full Play In Editor session would spawn a pawn that can collide with the very actors being baked, so it is never the right choice here.

Soft Body (Anim Sequence) bakes never start a session at all; they are sampled directly from the assets.

The bake button

Reads Start Simulate Capture, or Bake Animation for Soft Body (Anim Sequence). While a capture is running it becomes Cancel, with a progress bar and a frame counter beside it.

Warning

Don't stop the play session yourself while a capture is running — the bake aborts and nothing is written. Let it finish, or press Cancel.

Output logs

Every message from the bake, tagged [Info], [Warning] or [Error], ending with the path of each generated asset. Collapsible via the arrow in its header.

Read the warnings. Several conditions produce a bake that succeeds but doesn't play back correctly — a missing Persistent IDs setting, an instanced bake that fell back to compound, a capture where nothing moved — and each one says so here.