Boolean Fracture geometry node

Fractures the input geometry using cutting surfaces.

On this page	Inputs Outputs Parameters Pieces Output Attributes Output Groups Boolean Settings
Since	17.0

This SOP fractures the input mesh using one or more cutting surfaces. Similar to Voronoi Fracture, this is a higher-level node (based on the Boolean SOP) that handles common fracturing-related tasks such as naming pieces, recomputing normals, and building constraints between adjacent pieces.

Inputs ¶

Geometry to Fracture

The polygonal geometry that will be fractured.

Cutting Surface

The polygonal cutting surfaces to fracture the geometry with.

Outputs ¶

Fractured Geometry

The fractured polygonal geometry.

Constraint Geometry

Geometry containing a point for each piece, and polygon lines connecting pieces that are adjacent. This is useful for creating a constraint network.

Parameters ¶

Group

The geometry to be fractured. If no group is specified, the full input geometry will be fractured.

Pieces ¶

Name Attribute

Specifies how the name primitive attribute (which identifies the primitives belonging to each piece) is created.

Overwrite

Constructs the name by combining the Piece Prefix with the piece number.

Append

If the original geometry already has a name primitive attribute, it is prefixed with the Fracture Namespace and then the Piece Prefix and piece number are appended to it. This is useful when performing multiple levels of fracturing.

Fracture Namespace

Adds a prefix to the name of each input piece when Name Attribute is set to Append. This can be useful for avoiding duplicate piece names or grouping the new pieces that are created.

Piece Prefix

The prefix applied to the name of each piece created by the fracture.

Compute Interior Normals

Computes vertex normals on the edges of the interior geometry, so that they will have a cusped appearance.

Interior Cusp Angle

Computes vertex normals on the edges of the interior geometry with angles greater than this angle, so that they will have a cusped appearance.

Exterior Normals

Specifies how to compute or update vertex normals for the input geometry.

Preserve Existing Normals

Only compute vertex normals if the input geometry does not already have normals and Compute Interior Normals is enabled.

Recompute Normals

Always compute vertex normals for the input geometry.

Do Not Compute Normals

Do not compute normals for the input geometry. If Compute Interior Normals is still enabled, though, smooth normals will be computed.

Exterior Cusp Angle

Computes vertex normals on the edges of the input geometry with angles greater than this angle, so that they will have a cusped appearance.

Output Attributes ¶

Attribute Name Prefix

Specifies a prefix for the attribute or group names specified by the Primitive Piece, Interior Group, and Exterior Group parameters. This can make it easier to create unique attribute names when performing multiple levels of fracturing.

Primitive Piece

The name of the attribute containing the piece number with which each primitive is associated.

Copy Cutting Surface Attributes

Copy attributes from the input cutting surface to the output piece’s interior geometry.

Point Attributes

The point attributes to copy from the cutting surface to the points of the output piece’s interior geometry.

Vertex Attributes

The vertex attributes to copy from the cutting surface to the vertices of the output piece’s interior geometry.

Primitive Attributes

The primitive attributes to copy from the cutting surface to the primitives of the output piece’s interior geometry.

Output Groups ¶

Interior Group

The group containing any primitives in the interior surfaces created during fracturing.

Exterior Group

The group containing the primitives in the original input geometry.

Merge with Existing Groups

If the interior and exterior groups already exist on the geometry from a previous fracture, the new interior primitives will be added to the interior group and the original exterior group will be preserved. This behavior results in an interior group that contains all of the interior primitives created by multiple fracture operations (which can be useful for the RBD Interior Detail SOP). Otherwise, the interior group will be overwritten to only contain the interior primitives added by this node, and the exterior group will contain all of the input primitives.

Interior Seams

Creates a group containing edges representing the seams where the cutting geometry intersects itself.

Exterior Seams

Creates a group containing edges representing the seams where the cutting geometry intersects the original input geometry.

Pieces Inside Cutting Geometry

Creates a primitive group containing the pieces that are enclosed by the cutting geometry. This is supported when the input geometry and cutting geometry are both treated as a solid.

Surface Inside Cutting Geometry

Creates a group containing the polygons from the original input geometry that are enclosed by the cutting geometry. This is supported when the cutting geometry is treated as a solid.

Boolean Settings ¶

Treat Geometry As

Whether to treat this geometry like the boundary of a solid object, or as a flat surface with no interior or exterior.

Treat Cutting Geometry As

Whether to treat this geometry like the boundary of a solid object, or as a flat surface with no interior or exterior.

Detriangulate

Internally, this node converts the input geometry to triangles. This controls whether to convert the triangulated geometry back to N-gons matching the originals for output.

All Polygons

Merge neighboring triangles originating from the same input polygon back together.

Only Unchanged Polygons

If an input polygon is cut as part of the operation, keep it as triangles. Otherwise put triangulated polygons back together.

No polygons

Output the triangulated geometry.

Assume seam polygons are flat

Most “flat” polygons are not technically flat because of floating-point precision issues. This ignores those kinds of differences when de-triangulating the output. The default (on) is fine in almost all cases, but you may want to turn this off if you are doing procedural booleans on geometry with extremely fine detail/separation between surfaces. Turning this off will result in more triangles in the output.

See the tips and notes above for more information.

Collapse tiny seam-adjacent edges

Even if you try very hard to align edges on the two models you are combining, tiny numeric precision errors can (and usually will) cause the edges to be microscopically mis-aligned, creating extra edges in the output. When this option is on, the node intelligently fuses these tiny edges away. You should not turn this off unless you really know that you want microscopically thin polygons for some reason.

Edge length threshold

When Collapse tiny seam-adjacent edges is on, edges this length or smaller are automatically fused in the output.