Support OBJ writing for polygons and update .save interface to infer file type

coxeter/io.py

@@ -45,8 +45,13 @@ def to_obj(shape, filename):
 
     content += "\n"
 
-    for f in shape.faces:
-        content += f"f {' '.join([str(v_index + 1) for v_index in f])}\n"
+    if shape.__getattribute__("faces"):
+        for f in shape.faces:
+            content += f"f {' '.join([str(v_index + 1) for v_index in f])}\n"
+    elif shape.__getattribute__("num_vertices"): # Pack all vertices into one facet
+        content += f"f {' '.join([str(i + 1) for i in range(shape.num_vertices)])}\n"
+    else:
+        raise TypeError(f"Unsupported shape type `{type(shape)}` was provided.")
 
     content = content[:-1]
 

coxeter/shapes/polygon.py

@@ -838,3 +838,22 @@ def to_hoomd(self):
 
         self.centroid = old_centroid
         return hoomd_dict
+
+    def save(self, filename):
+        """Save the polyhedron object to a file using methods from ``coxeter.io``.
+
+        Args:
+            filename (str, pathlib.Path, or os.PathLike):
+                The name or path of the output file, including the extension which must
+                be one of the following: .obj, .off, .stl, .ply, .vtk, .x3d, or .html
+
+        Raises
+        ------
+            ValueError: If the file type does not match one of the valid outputs.
+            OSError: If open() encounters a problem.
+        """
+        filetype = Path(filename).suffix.lstrip(".").capitalize()
+        if filetype == "OBJ":
+            io.to_obj(self, filename)
+        else:
+            raise ValueError("filetype must be one of the following: .obj")

coxeter/shapes/polyhedron.py

@@ -5,6 +5,7 @@
 
 import warnings
 from functools import cached_property
+from pathlib import Path
 
 import numpy as np
 import rowan
@@ -1022,22 +1023,20 @@ def to_hoomd(self):
         self.centroid = old_centroid
         return hoomd_dict
 
-    def save(self, filetype, filename):
+    def save(self, filename):
         """Save the polyhedron object to a file using methods from ``coxeter.io``.
 
         Args:
-            filetype (str):
-                The file format to export polyhedron to. Must be one of the following:
-                OBJ, OFF, STL, PLY, VTK, X3D, HTML.
-
             filename (str, pathlib.Path, or os.PathLike):
-                The name or path of the output file, including the extension.
+                The name or path of the output file, including the extension which must
+                be one of the following: .obj, .off, .stl, .ply, .vtk, .x3d, or .html
 
         Raises
         ------
-            ValueError: If filetype is not one of the required strings.
+            ValueError: If the file type does not match one of the valid outputs.
             OSError: If open() encounters a problem.
         """
+        filetype = Path(filename).suffix.lstrip(".").capitalize()
         if filetype == "OBJ":
             io.to_obj(self, filename)
         elif filetype == "OFF":
@@ -1054,6 +1053,6 @@ def save(self, filetype, filename):
             io.to_html(self, filename)
         else:
             raise ValueError(
-                "filetype must be one of the following: OBJ, OFF, "
-                "STL, PLY, VTK, X3D, HTML"
+                "filetype must be one of the following: .obj, .off, .stl, .ply, .vtk, "
+                ".x3d, or .html"
             )