[Blender 3.6] UV Packer

cg/utils/custom_parser.py

@@ -0,0 +1,55 @@
+# coding: utf-8
+# https://blender.stackexchange.com/a/134596
+
+import argparse
+import sys
+
+
+class CustomArgumentParser(argparse.ArgumentParser):
+    """
+    This class is identical to its superclass, except for the parse_args
+    method (see docstring). It resolves the ambiguity generated when calling
+    Blender from the CLI with a python script, and both Blender and the script
+    have arguments. E.g., the following call will make Blender crash because
+    it will try to process the script's -a and -b flags:
+    >>> blender --python my_script.py -a 1 -b 2
+
+    To bypass this issue this class uses the fact that Blender will ignore all
+    arguments given after a double-dash ('--'). The approach is that all
+    arguments before '--' go to Blender, arguments after go to the script.
+    The following calls work fine:
+    >>> blender --python my_script.py -- -a 1 -b 2
+    >>> blender --python my_script.py --
+    """
+
+    @staticmethod
+    def _get_argv_after_doubledash():
+        """
+        Given the sys.argv as a list of strings, this method returns the
+        sublist right after the '--' element (if present, otherwise returns
+        an empty list).
+        """
+        try:
+            idx = sys.argv.index("--")
+            return sys.argv[idx+1:]  # the list after '--'
+        except ValueError as e:  # '--' not in the list:
+            return None
+
+    # overrides superclass
+    def parse_args(self, args=None, namespace=None):
+        """
+        This method is expected to behave identically as in the superclass,
+        except that the sys.argv list will be pre-processed using
+        _get_argv_after_doubledash before. See the docstring of the class for
+        usage examples and details.
+        """
+        return super().parse_args(
+            args=args or self._get_argv_after_doubledash(),
+            namespace=namespace
+        )
+
+    def parse_known_args(self, args=None, namespace=None):
+        return super().parse_known_args(
+            args=args or self._get_argv_after_doubledash(),
+            namespace=namespace
+        )