VDB Clip

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VDB Clip

The VDB Clip allows you to remove (deactivate) voxels from VDB volume primitives that are outside the bounding box of the geometry given in the second input. This also allows you to use a mask VDB or camera to specify where activated voxels will be present.
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Summary:

    This SOP is useful for times when you don't want to use the VDB Combine node and you just want to have something simple to mask off where active vdbs are.  If you're new to VDBs, then please visit the VDB lesson at Houdini For the New Artist II.

In order for this node to work, you'll need to select a camera, plug in geometry, or plug in a mask volume with the second input.  

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Main Parameters:

Keep Inside:

--  This will ensure that anything inside the mask geo/volume/camera gets kept.   Turn this off if you want to invert the effect.

Clip To:

-- Geometry =  This will take the bounding box of geometry that you've plugged into the second input.  If the voxels find themselves within the box, then they are kept.  Otherwise they are de-activated.

--  Camera = This will take a Camera and use it's view frustum to mask off the vdb.  Anything inside the frustum is kept while anything outside is deactivated. 

--  Mask VDB =  This requires a SDF VDB plugged into the second input.  Any negative voxel values will keep the original voxels active.  Any positive voxel values on the mask will deactivate the original VDB volume.

Padding:

--  This creates additional padding in x,y,z around the object/volume/camera that's being used to generate the mask.