made Mesh not generate if vertices is [] and not just None.

ursina/mesh.py

@@ -72,7 +72,7 @@ def __init__(self, vertices=None, triangles=None, colors=None, uvs=None, normals
             if value is None:
                 setattr(self, name, [])
 
-        if self.vertices is not None:
+        if self.vertices:
             self.generate()
 
 
@@ -192,6 +192,10 @@ def __repr__(self):
         else:
             return self.recipe
 
+    def __str__(self):
+        if hasattr(self, 'name'):
+            return self.name
+
 
     def __add__(self, other):
         self.vertices += other.vertices
@@ -205,6 +209,7 @@ def __add__(self, other):
         self.uvs += other.uvs
 
 
+
     def __deepcopy__(self, memo):
         m = Mesh(self.vertices, self.triangles, self.colors, self.uvs, self.normals, self.static, self.mode, self.thickness)
         m.name = self.name