add a new sv_bmesh_ops module, which is not used for generating bmesh (#2533)

30ba6030 · Dealga McArdle · GitHub · ced0a90d · 30ba6030
--- a/utils/modules/sv_bmesh_ops.py
+++ b/utils/modules/sv_bmesh_ops.py
+# This file is part of project Sverchok. It's copyrighted by the contributors
+# recorded in the version control history of the file, available from
+# its original location https://github.com/nortikin/sverchok/commit/master
+#  
+# SPDX-License-Identifier: GPL3
+# License-Filename: LICENSE
+
+import bmesh
+
+def recursive_search(found_set, current_vertex):
+    """
+    helper function for "find_islands_treemap"
+    : finds all connected vertex indices, given an input set and vertex of bm.
+    """
+
+    for polygon in current_vertex.link_faces:
+        for vert in polygon.verts:
+            if vert.index not in found_set:
+                found_set.add(vert.index)
+                found_items = recursive_search(found_set, vert)
+                if found_items:
+                    found_set.update(found_items)
+                    
+    return found_set
+
+def vertex_emitter(bm):
+    """
+    helper function for "find_island_treemap"
+    : turns a bm into an iterable of verts, to use next with.
+    """
+    for v in bm.verts:
+        yield v
+
+def find_islands_treemap(bm):
+    """
+    importable function to obtain all islands in a given bmesh.
+    : returns a dict of island integers and the vertex indices associated with that island.
+    """
+    
+    island_index = 0
+    islands = {}
+
+    vertex_iterator = vertex_emitter(bm)
+    vertex_0 = next(vertex_iterator)
+    islands[island_index] = recursive_search({0}, vertex_0)
+        
+    for vertex in vertex_iterator:
+        if vertex.index not in islands[island_index]:
+            island_index += 1
+            islands[island_index] = recursive_search({vertex.index}, vertex)
+
+    return islands
+
+# usage
+# island_dict = find_islands_treemap(bm)
+# returns a dict of islands and associated vertices