MCrack — Documentation

Requires Blender 5.2 or later.

1. In Blender, open Edit > Preferences > Get Extensions.

2. Click the dropdown arrow at the top right of the window and choose Install from Disk…

3. Select MCrack-1.0.0.zip. Blender asks you to confirm one permission — Files, because the add-on reads its fracture setups from a blend library on disk.

4. The extension installs and enables itself. Press N in the 3D Viewport and the MCrack tab is there, in the sidebar.

To update later, install the newer zip the same way; it replaces the previous version. To remove it, find MCrack in the Add-ons list and uninstall it.

In the 3D viewport, press N to open the sidebar and pick the MCrack tab. The panel has three parts, top to bottom.

MCrack works on the active mesh object. With anything else selected the panel says so and the buttons are greyed out.

Select a mesh object and click Crack or Cut. The setup is added as a Geometry Nodes modifier and becomes the selected layer.

Clicking again always adds another layer — nothing is ever replaced. The same setup can be added as many times as you like; each copy keeps its own settings and shares a single node group, so the file does not grow with every layer.

A new layer is not a copy of the one before it: its Cutter Seed and Cutter Noise Seed are drawn at random, so a second Crack gives a different break instead of the same one twice.

Each layer is one row, six controls from left to right.

Under the list, the two arrows move the selected layer up or down the stack. Order matters: a layer only ever works on the result of the layers above it.

Shatters the geometry into islands, or shatters one island alone.

Splits the geometry with one cutter you place yourself. Size, resolution and noise behave as they do on Crack.

To break one fragment out of forty you need to know its number. Click the numbers icon on a layer row and every fragment of that layer gets its id drawn at its centre, straight in the viewport.

Read the number, then on a Crack layer turn on Crack One Island and type it into Island id. That shard is the one that breaks.

Each layer shows the ids of its own attribute, so the numbers change as you move the preview down the stack. They also follow the geometry: change a seed, move the object, and the labels move with it.

Layers hand their fragments to the layer below through a named attribute. Name is the attribute a layer writes; Previous Name is the one it reads from above. Two layers writing the same name would collide, so each new layer takes the next free one:

island · island2 · island3

Delete a layer and its number goes back into circulation for the next one you add. Type a name yourself and nothing ever overwrites it — the numbering only fills names it chose.

The two seed parameters are drawn at random when a layer is added. Reset puts them back to the setup defaults rather than drawing new ones, so to try another break, type a different Cutter Seed or add a fresh layer.