Implementing 'Brush - Patch' Functionality from MeshInspector in Python

[jeahyuklee]

Hello!

How can I implement a feature similar to 'Mesh Edit - Brush - Patch' from MeshInspector in Python? Could you provide an example code for this functionality?

Thank you!

[Grantim]

Hello!

Patch tool actually do two things:

1. Remove all faces that are inside the brush area
2. fill appeared holes

You can do it in c++ with:

MeshLib/source/MRMesh/MRRegionBoundary.h

Lines 33 to 37 in 6a67dd1

	/// deletes all region faces, inner edges and vertices, but keeps boundary edges and vertices of the region (or whole mesh if region is null);
	/// returns edge loops, each having deleted region faces on the left, and not-region faces or holes on the right
	MRMESH_API std::vector<EdgeLoop> delRegionKeepBd( Mesh & mesh, const FaceBitSet * region = nullptr );
	inline std::vector<EdgeLoop> delRegionKeepBd( Mesh & mesh, const FaceBitSet & region )
	{ return delRegionKeepBd( mesh, &region ); }

and

MeshLib/source/MRMesh/MRFillHoleNicely.h

Lines 43 to 49 in 6a67dd1

	/// fills a hole in mesh specified by one of its edge,
	/// optionally subdivides new patch on smaller triangles,
	/// optionally make smooth connection with existing triangles outside the hole
	/// \return triangles of the patch
	MRMESH_API FaceBitSet fillHoleNicely( Mesh & mesh,
	EdgeId holeEdge, ///< left of this edge must not have a face and it will be filled
	const FillHoleNicelySettings & settings );

note that all c++ function are available in meshlib python modules after 3 version. Now to install latest version you need to manually set it up for pip:

pip install meshlib==3.0.1.205

but after next release you will be able to install it simply with getting latest version from pip.

You code in python should look somewhat like this:

from meshlib import mrmeshpy as mm

mesh = mm.loadMesh( "path/to/mesh.stl" )
facesToPatch = mm.FaceBitSet()
facesToPatch.resize( mesh.topology.getValidFaces().size() )
facesToPatch.set( mm.FaceId( 1 ), True ) # set some faces that you want to patch, or fill the bitset in other way

newHoles = mm.delRegionKeepBd(mesh,facesToPatch)
for hole in newHoles:
    mm.fillHoleNicely( mesh, hole[0], mm.FillHoleNicelySettings() )

mm.saveMesh( mesh, "path/to/export_mesh.stl" )

[Grantim]

Also please note that it is recommended to setup these parameters for FillHoleNicelySettings

    /// Subdivision is stopped when all edges inside or on the boundary of the region are not longer than this value
    float maxEdgeLen = 0; // set average edge length of the mesh, or of the corresponding hole

    /// Maximum number of edge splits allowed during subdivision
    int maxEdgeSplits = 1000; // set INT_MAX or to stop subdivision by `maxEdgeLen`