Prefabs

A prefab is an asset that stores a block group (including props) so you can place it many times. Make anything that repeats, such as houses, streetlights and towers, into a prefab. Copies placed as links all change at once when you edit the original prefab.

How to open

Method	Action
Window › Prefabs	Opens the Prefabs panel (library).
Content Browser	Find them under Prefabs in the source tree on the left (folders by tag).
Tools › Save selection as prefab	Saves the current selection as a prefab right away.
Double-click a prefab	Opens the prefab edit window (from both the Prefabs panel and the Content Browser).

Quick start

Box-select the building to save with the Selection tool (Q).
In the Save selection group of the Prefabs panel (Window › Prefabs), type a name and tags, then press Save selection.
Choose the prefab in the list and press Place (or drag it into the viewport).
Click the viewport to place it. R = rotate, F = flip, Esc = stop.
After placing, the tool switches to Selection and the placed copy is selected. Move it right away with W · E · R.
To edit, double-click the prefab, edit it in the edit window and press Save. All linked placed copies change.

Creating

Method	Result
Prefabs panel Save selection	Saves with a Name and Tags (comma-separated).
Tools › Save selection as prefab	Saves right away with the name “Prefab MMdd_HHmm”. Rename it later.
Outliner right-click Save as prop (prefab)	Saves only that actor’s blocks and props as a prefab. Cells of other actors within the bounds are left out.
Model import Convert to blocks	Converts an external model to vanilla blocks and saves it as a prefab (tag Model conversion) (Importing custom models).

If the selection contains no blocks, nothing is saved.

Placing

Input	Action
Prefabs panel Place · edit window Place	Starts placement mode.
Drag from the Prefabs panel or Content Browser into the viewport	Starts placement mode at that spot.
Click	Places with the pivot at the cell under the mouse. After placing, the tool switches to Selection.
`Shift`+click	Places and stays in placement mode (place several).
`R` · `F`	Rotate 90° · flip left/right (block orientations too)
`Esc`	End placement

Each placed prefab is one actor in the Outliner.

Placement options

This is the Placement options group of the Prefabs panel.

Field	Default	Meaning
Place as link	On	Keeps the placed copy linked to the original. When the original is saved, it updates too.
Clear with empty cells	Off	Empty cells (air) in the prefab remove existing blocks at that spot.
Place props too		Also places the props contained in the prefab.
Keep edited blocks		During bulk updates, cells you edited after placing are left as they are.

Updating from a placed copy

Edit one copy placed as a link directly in the world.
Put the mouse cursor over it.
Press Update from the one under the cursor in the Prefabs panel.
The prefab is saved as a new revision and all linked copies are updated. Undo it with a single Ctrl+Z.

Prefab edit window

Opens when you double-click a prefab or press Edit in the panel. It is a floating window you can move outside the editor.

Since 0.9.10: The left side of the edit window is a real 3D edit viewport instead of a picture. The old routine of placing a prefab → cutting a hole → reselecting and saving is now done in one window.

3D edit viewport

This is a separate world containing only the prefab’s blocks. It works independently of the main world and the main undo history. The main world does not change until you save.

Top row	Meaning
7 tool buttons	Place 1 · Break 2 · Eyedropper 3 · Select 4 · Shape 5 · Brush 6 · Fill 7
Block to place · Main block	Block to place in this window (including state). Main block = take the current block from the main screen
View	Unlit (F2) · Lit (F1) · Wireframe (F3) · Game view (F6) · Path tracing (F7)

When first opened, the view is Unlit. The prefab’s minimum corner sits at the floor grid (0, 0, 0).
Camera controls are the same as in the main viewport.

Key (when the window has focus)	Action
`1` – `7` · `Q` · `Tab`	Switch tools
`W` · `E` · `R`	Region gizmo (when there is a selection)
`R` · `Shift`+`R` · `X` · `Shift`+`X` · `U`	Rotate · flip
Arrow keys · `PgUp` · `PgDn` · `K`	Move · array
`Del` · `Ctrl`+`C` · `Ctrl`+`X` · `Ctrl`+`V` · `Ctrl`+`I` · `Ctrl`+`A`	Delete · copy · cut · paste · invert · all
`[` · `]`	Brush · shape size
`F` · `G` · `H`	Frame · grid · hide
`F1` – `F7`	View mode
`Ctrl`+`Z` · `Ctrl`+`Y`	Undo · redo within this window
`Esc`	Cancel drag → clear selection

Right-side tabs

Tab	Contents
Prefabs	Name · tags · pivot · bake orientation · block list · size and revision info
Tools	Block state · pattern · shape · brush · fill · selection operations · replace blocks (same as the main Tools panel)

Prefabs tab field	Meaning
Name · Tags	Separate tags with commas (e.g. castle wall, medieval).
Pivot (placement anchor) X · Y · Z	The cell in the prefab that lands on the cursor cell when placing. Bottom center = the center of the bottom
Bake orientation	Rotate Y 90° · Flip left/right — saves the blocks rotated or flipped (changes the default orientation when placing).
Block	List of counts per block type. Change the chosen block (to another block) · Delete (to air)

Bottom button	Action
Save	Saves as a new revision of the same prefab. If blocks changed, placed copies linked in the world are updated too.
Place	Saves, then starts placement mode.
Duplicate as new prefab	Saves as a different prefab (links stay with the original).
Export to file	Exports as a single `.npprefab` file.
Close	If there are unsaved changes, asks Discard and close or Keep editing.

If you change only the pivot and save, copies already placed stay where they are.
Updated placed copies remain in the actor they originally belonged to.
A prefab with no blocks cannot be saved.

Revisions and renaming

Saving a prefab does not overwrite it; it creates a new revision (r2, r3 …). A new file such as <name>_v2.npprefab is created.
The library shows only the highest revision of each prefab. Old revision files remain in the folder.
Rename: Name in the Prefabs panel (F2) or Content Browser right-click Rename. It becomes a new revision of the same prefab, and links with placed copies are kept.

What you want	How
Export	Prefabs panel Export · edit window Export to file · Content Browser right-click Export to file… (choose several to export to a folder)
Import	Choose a `.npprefab` file with Prefabs panel Import or Content Browser Import

Import follows these rules.

Case	Result
Prefab not seen before	Added to the library.
Higher revision of the same prefab	Updated to the latest.
Same or lower revision of the same prefab	Added as a copy without overwriting.

Options

Setting	Where	Meaning
Place as link · Clear with empty cells · Place props too · Keep edited blocks	Prefabs panel › Placement options	The “Placement options” table above
Name · Tags	Prefabs panel › Save selection	Name and tags of the new prefab
Search · Tags	Top of the Prefabs panel	Filter by name and tag
Pivot · Bake orientation	Edit window › Prefabs tab	Placement anchor and default orientation

Shortcuts

Key	Action
`R` · `F` (while placing)	Rotate · flip
`Shift`+click (while placing)	Keep placing
`Esc` (while placing)	End placement
`F2`	Rename (Prefabs panel · Content Browser)
Double-click · `Enter`	Open the edit window

For keys inside the edit window, see the “3D edit viewport” table above.

Tips / cautions

Prefab files are saved in prefabs/ in the project folder. If the world has not been saved yet, they are saved in the user folder (%APPDATA%\NPEditor\prefabs).
Link information is saved in the world file (.npworld). If you move only the prefab files to another PC, the links do not follow.
One prefab can be up to about 16.77 million blocks.
With Inserted modules in Face extrude, you can insert a prefab into a wall every N blocks.
Undo in the prefab edit window works only inside the window. Updates applied to the world by saving are undone with Ctrl+Z in the main window.