TriangleMesh newly only holds indexed_triangle_set and
TriangleMeshStats. TriangleMeshStats contains an excerpt of stl_stats.
TriangleMeshStats are updated when initializing with indexed_triangle_set.
Admesh triangle mesh fixing is newly only used when loading an STL.
AMF / 3MF / OBJ file formats are already indexed triangle sets, thus
they are no more converted to admesh stl_file format, nor fixed
through admesh repair machinery. When importing AMF / 3MF / OBJ files,
volume is calculated and if negative, all faces are flipped. Also
a bounding box and number of open edges is calculated.
Implemented its_number_of_patches(), its_num_open_edges()
Optimized its_split(), its_is_splittable() using a visitor pattern.
Reworked QHull integration into TriangleMesh:
1) Face normals were not right.
2) Indexed triangle set is newly emitted instead of duplicating
vertices for each face.
Fixed cut_mesh(): Orient the triangulated faces correctly.
Type handling is mainly done using templates.
Template Slic3r::ClassTraits is used to store info about exported types (perl class name). Currently only perl class name and refference name is used.
Template values are initialized by REGISTER_CLASS macro. This macro is used in .cpp file of class ( it needs to be used exactly for each type).
Ref<type> class is used to return value as perl reference. Operator overloading is used to make c++ and XSpp happy, only pointer value should be possible to return.
Clone<type> class is used to return copy of value ( using new and copy constructor). Copy is created on assigment, this should be probably improved (memory leak on multiple assignments).
It is overloaded to be able to return type, type* and type&.
Typechecking in ExtrusionEntityCollection updated to check all passed types.
