How do I keep track of vertex/edge/face origin during boolean operation?

[PhilNamesnik8463]

Consider two meshes from STL files that are intersecting. After I apply some boolean operation (e.g. intersection), the resulting mesh consists of a combination of vertices/edges/faces of the original meshes. Is it possible to keep track of the origin of those elements? After the boolean operation I want to write to an STL file again, but the mesh elements should be split by origin, as in an STL file with multiple bodies. The following sketch clarifies the idea:

[Grantim]

Hello!

We have special output struct in meshboolen

MeshLib/source/MRMesh/MRBooleanOperation.h

Lines 49 to 56 in 3b31903

	/** \struct MR::BooleanResultMapper
	* \brief Structure to map old mesh BitSets to new
	* \details Structure to easily map topology of MR::boolean input meshes to result mesh
	*
	* This structure allows to map faces, vertices and edges of mesh `A` and mesh `B` input of MR::boolean to result mesh topology primitives
	* \sa \ref MR::boolean
	*/
	struct BooleanResultMapper

to map origins of result mesh primitives.

Also if you want to save 2 individual components it might be easier on to call BooleanOperation::Inside/Outside(A/B) to gat them as separate meshes

[PhilNamesnik8463]

Thank you very much, this is exactly what I need!
Regarding your second point: I simplified the problem a bit for explanatory reasons. In my actual problem, one mesh is watertight and the other one is not but rather slices the watertight mesh into two volumes like that:

Inside and outside only work for watertight geometries and intersection is the correct operation that yields the desired result.

Edit: I work with Python and just tried to implement your suggested method in the following way:
def get_sliced_mesh(outer: mm.Mesh, cut: mm.Mesh): mapper = mm.BooleanResultMapper() bool_result = mm.boolean(outer, cut, mm.BooleanOperation.DifferenceAB, mapper=mapper) return bool_result.mesh, mapper

However I get the error:
TypeError: boolean(): incompatible function arguments. The following argument types are supported: 1. (meshA: meshlib.mrmeshpy.Mesh, meshB: meshlib.mrmeshpy.Mesh, operation: meshlib.mrmeshpy.BooleanOperation, rigidB2A: meshlib.mrmeshpy.AffineXf3f, mapper: meshlib.mrmeshpy.BooleanResultMapper = None, cb: meshlib.mrmeshpy.func_bool_from_float = '{}') -> meshlib.mrmeshpy.BooleanResult 2. (meshA: meshlib.mrmeshpy.Mesh, meshB: meshlib.mrmeshpy.Mesh, operation: meshlib.mrmeshpy.BooleanOperation, rigidB2A: meshlib.mrmeshpy.AffineXf3f, mapper: meshlib.mrmeshpy.BooleanResultMapper = None, cb: meshlib.mrmeshpy.func_bool_from_float = '{}') -> meshlib.mrmeshpy.BooleanResult 3. (meshA: meshlib.mrmeshpy.Mesh, meshB: meshlib.mrmeshpy.Mesh, operation: meshlib.mrmeshpy.BooleanOperation, params: meshlib.mrmeshpy.BooleanParameters = '{}') -> meshlib.mrmeshpy.BooleanResult 4. (meshA: meshlib.mrmeshpy.Mesh, meshB: meshlib.mrmeshpy.Mesh, operation: meshlib.mrmeshpy.BooleanOperation, params: meshlib.mrmeshpy.BooleanParameters = '{}') -> meshlib.mrmeshpy.BooleanResult

How am I supposed to use the map function of the BooleanResultMapper?

[Grantim]

Our boolean implementation operates with "surfaces" rather then "volumes", so in this case, while intersection contours are consistent and closed, Inside/Outside should work too (the image looks more like Blue-Red, which in would be Outside Blue and Inverted Inside Red stitched together). You can try in MesInspector application:

[Grantim]

However I get the error:
TypeError: boolean(): incompatible function arguments. The following argument types are supported: 1. (meshA: meshlib.mrmeshpy.Mesh, meshB: meshlib.mrmeshpy.Mesh, operation: meshlib.mrmeshpy.BooleanOperation, rigidB2A: meshlib.mrmeshpy.AffineXf3f, mapper: meshlib.mrmeshpy.BooleanResultMapper = None, cb: meshlib.mrmeshpy.func_bool_from_float = '{}') -> meshlib.mrmeshpy.BooleanResult 2. (meshA: meshlib.mrmeshpy.Mesh, meshB: meshlib.mrmeshpy.Mesh, operation: meshlib.mrmeshpy.BooleanOperation, rigidB2A: meshlib.mrmeshpy.AffineXf3f, mapper: meshlib.mrmeshpy.BooleanResultMapper = None, cb: meshlib.mrmeshpy.func_bool_from_float = '{}') -> meshlib.mrmeshpy.BooleanResult 3. (meshA: meshlib.mrmeshpy.Mesh, meshB: meshlib.mrmeshpy.Mesh, operation: meshlib.mrmeshpy.BooleanOperation, params: meshlib.mrmeshpy.BooleanParameters = '{}') -> meshlib.mrmeshpy.BooleanResult 4. (meshA: meshlib.mrmeshpy.Mesh, meshB: meshlib.mrmeshpy.Mesh, operation: meshlib.mrmeshpy.BooleanOperation, params: meshlib.mrmeshpy.BooleanParameters = '{}') -> meshlib.mrmeshpy.BooleanResult
How am I supposed to use the map function of the BooleanResultMapper?

I think it just misses rigidB2A parameter and cannot find correct function overload, can you try like this:

def get_sliced_mesh(outer: mm.Mesh, cut: mm.Mesh): 
    mapper = mm.BooleanResultMapper()
    bool_result = mm.boolean(outer, cut, mm.BooleanOperation.DifferenceAB, None, mapper)
    return bool_result.mesh, mapper

[PhilNamesnik8463]

Thank you so much! I just used the wrong boolean operation and now I get exactly what I wanted.