Houdini 20.5 Nodes Geometry nodes

VDB Convex Clip SDF geometry node

Clips an SDF VDB by a convex hull.

On this page

This operaton clips an SDF VDB by a convex hull defined by a set of points. This is equivalent to using a Shrink Wrap SOP to build a convex hull, VDB from Polygons SOP to convert the hull to an SDF VDB, and a VDB Combine SOP to perform the CSG operation. A key advantage of ths node is most of those stages can be done implicitly so will be much faster, especially when the operation is trivial.

If the convex hull has no points, it is treated as present everywhere. If it has one to three points, it is considered degenerate and will be absent everywhere.

In the case of Union, a convex hull without points is treated as empty to avoid creating an infinite SDF.

Parameters

VDBs to Clip

VDBs to perform a CSG operation with the convex hull. These must be signed distance fields. The bandwidth of each field is respected in the CSG operation.

Convex Hull Points

Subset of points to use from the second input to define the convex hull.

Operation

How to combine the convex hull with the existing signed distance field.

Intersect

Only parts of the signed distance field inside the convex hull are kept.

Subtract

The convex hull is removed from the signed distance field.

Union

The convex hull is merged with the sigend distance field.

Voxel Offset

Number of voxels to expand the convex hull outwards. Negative values wil shrink the hull.

NOTE: This is done by offseting the half planes so corners are not accurate.

World Offset

Distance to expand the convex hull outwards. Negative values wil shrink the hull.

NOTE: This is done by offseting the half planes so corners are not accurate.

Locals

See also

Geometry nodes