Houdini 20.5 Nodes Geometry nodes

VDB Fracture geometry node

Cuts level set VDB volume primitives into multiple pieces.

Since 12.5

This node splits level set VDB volume primitives into multiple fragments.

To fracture the VDB primitives, you must supply some cutter geometry in the second input. The optional third input specifies points onto which the cutter geometry will be instanced (or transformed onto) to perform the cutting.

Typically, the first input is the result from a VDB from Polygons node. The fractured result can then be converted back to polygons seamlessly by using the Convert VDB node with the original polygons as the second input.

Note

The cutter geometry must be a closed surface but does not need to be manifold. The cutter geometry can contain self intersections and degenerate faces. Normals on the cutter geometry are ignored.

Note

The reference points supplied in the optional third input can have attributes that control how the cutter is transformed onto them. This follows the same rules as what the Copy node does, except for scaling. Scaling SDFs correctly require that the level set be rebuilt at the same time. Thus you must scale your cutter geometry appropriately first.

Parameters

Group

The name(s) of the VDB primitives to fracture. See specifying volumes.

Separate Cutters by Connectivity

The cutter geometry will be classified by point connectivity. Each connected component will be cut separately. Use this if an individual piece of cutting eometry has overlapping components.

Allow Cutter Overlap

Allow consecutive cutter instances to fracture previously generated fragments.

Center Cutter Geometry

If enabled, the cutter geometry will be first centered around its point position centroid.

Randomize Cutter Rotation

Apply a random rotation to each cutter as it is instanced onto each point.

Random Seed

Seed value for randomize cutter rotation.

Split Input Fragments into Primitives

Split input VDBs with disjoint fragments into multiple primitives, one per fragment.

If you have a tube and cut out the middle, the two ends might end up in the same VDB. This option will detect that and split the ends into two VDBs.

Note

This operation only needs to be performed if you plan on using the output fragments for collision detection. If you use multiple fracture nodes, then it is most efficient to only enable it on the very last fracture node.

Fragment Group

Specifies the group name to associate all fragments generated by this fracture. The residual fragments of the input VDBs are excluded from this group.

Visualization

The generated VDBs can be colored uniquely to make it easy to see the new pieces. The New Fragments option will leave the original pieces with their original coloring, only affecting the net-new pieces.

See also

Geometry nodes