CSG Operations

[LouisNoailles]

Environment

Operating System: Ubuntu 20.04
Version / Commit SHA: 0f93ce6
Other: compiler: g++, c++ 17

Describe the bug

I am trying to do csg operations such as union and I am doing this
`openvdb::FloatGrid::ConstPtr
copyOfGridA = grid->deepCopy(),
copyOfGridB = vdb->deepCopy();

    openvdb::FloatGrid::Ptr res = openvdb::tools::csgUnionCopy(*grid, *vdb);
    
    // Restore the original grids.
    grid = copyOfGridA->deepCopy();
    vdb = copyOfGridB->deepCopy();
    return res;`

the two grids have the same transform and I do no rotations on them but the final grid is equal to grid

Expected behavior

I would expect to have grid U vdb but I get only grid as a result

[danrbailey]

I might need a little more sample code to try and guess why you might not be getting the expected result, however I will say that given that you're deep-copying the inputs before calling openvdb::tools::csgUnionCopy(), it would probably make sense to just call openvdb::tools::csgUnion() which steals data from the second tree and inserts it into the first. In fact, we have been considering removing openvdb::tools::csgUnionCopy() as it's not used by any code in the library currently and the new threaded implementation of openvdb::tools::csgUnion() is just as fast.

[LouisNoailles]

I also tried csgUnion() like this :
`openvdb::FloatGrid::Ptr res = grid->deepCopy();
openvdb::FloatGrid::Ptr copy = vdb->deepCopy();

openvdb::tools::csgUnion(*res, *vdb)
// Restore the original grids.
vdb = copy->deepCopy();
return res;`

but same restult I only get in the union the content of "grid" and not "grid U vdb"

[LouisNoailles]

Is meshtoVolume produce a level set as openvdb understand it or to a for volume ? and is there a way to convert a volume t a level set?