OpenVDB can now natively construct tube level sets

[ghurstunither]

Some recently merged tools in the OpenVDB repo that seem relevant to this repo:

tools::createLevelSetDilatedMesh found here.

tools::createLevelSetCapsule, tools::createLevelSetTaperedCapsule, tools::createLevelSetTubeComplex found here.

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I wonder if CreateFromCurves could discretize curves like it already does (perhaps more coarsely—e.g., just two points per line segment?), but then call tools::createLevelSetTubeComplex instead of unioning a bunch of spheres at points to approximate a smooth tube.

I think this would

• Create faster execution time.
  • Unioning overlapping spheres means we're creating a bunch of voxels that are then destroyed when the next sphere is unioned in.
• Be exact up to the discretization of the curve.
  • You won't get a bumpy tube like you sometimes see right now.