From d164880064e0386427c4d18514c03101ee330512 Mon Sep 17 00:00:00 2001
From: mozman <me@mozman.at>
Date: Tue, 19 Mar 2024 17:53:07 +0100
Subject: [PATCH] add test for polygon orientation to revcloud.add_entity()

---
 examples/revcloud.py                     |  8 ++++++++
 src/ezdxf/revcloud.py                    | 18 +++++++++++++++---
 tests/test_05_tools/test_544_revcloud.py |  5 +++--
 3 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/examples/revcloud.py b/examples/revcloud.py
index 6780ce2a4..6fd76b582 100644
--- a/examples/revcloud.py
+++ b/examples/revcloud.py
@@ -39,7 +39,15 @@ def revcloud_entity():
     revcloud.add_entity(msp, [(0, 0), (1, 0), (1, 1), (0, 1)], segment_length=0.1)
     doc.saveas(CWD / "revcloud-entity.dxf")
 
+def revcloud_reverse_entity():
+    doc = ezdxf.new()
+    msp = doc.modelspace()
+
+    revcloud.add_entity(msp, [(0, 0), (0, 1), (1, 1), (1, 0)], segment_length=0.1)
+    doc.saveas(CWD / "revcloud-reverse-entity.dxf")
+
 
 if __name__ == "__main__":
     revcloud_manually()
     revcloud_entity()
+    revcloud_reverse_entity()
diff --git a/src/ezdxf/revcloud.py b/src/ezdxf/revcloud.py
index 3942ac9b9..b4e6f6357 100644
--- a/src/ezdxf/revcloud.py
+++ b/src/ezdxf/revcloud.py
@@ -3,7 +3,7 @@
 from __future__ import annotations
 from typing import Sequence, TYPE_CHECKING, Iterable, Any
 import math
-from ezdxf.math import UVec, Vec2
+from ezdxf.math import UVec, Vec2, has_clockwise_orientation
 from ezdxf.entities import LWPolyline, DXFEntity
 
 if TYPE_CHECKING:
@@ -83,8 +83,19 @@ def add_entity(
         dxfattribs: additional DXF attributes
 
     """
+    _vertices: list[Vec2] = Vec2.list(vertices)
+    if len(_vertices) < 3:
+        raise ValueError("3 or more points required.")
+    if not _vertices[0].isclose(_vertices[-1]):
+        _vertices.append(_vertices[0])
+    if len(_vertices) < 4:
+        raise ValueError("3 or more points required.")
+    bulge = REQUIRED_BULGE
+    if has_clockwise_orientation(_vertices):
+        bulge = -bulge
+
     end_width = segment_length * 0.1 if calligraphy else 0.0
-    lw_points = points(vertices, segment_length, end_width=end_width)
+    lw_points = points(vertices, segment_length, bulge=bulge, end_width=end_width)
     lwp = layout.add_lwpolyline(lw_points, close=True, dxfattribs=dxfattribs)
     lwp.set_xdata(REVCLOUD_PROPS, [(1070, 0), (1040, segment_length)])
     doc = layout.doc
@@ -103,5 +114,6 @@ def is_revcloud(entity: DXFEntity) -> bool:
     if not lwpolyline.has_xdata(REVCLOUD_PROPS):
         return False
     return all(
-        abs(p[0] - REQUIRED_BULGE) < 0.02 for p in lwpolyline.get_points(format="b")
+        abs(REQUIRED_BULGE- abs(p[0])) < 0.02
+        for p in lwpolyline.get_points(format="b")
     )
diff --git a/tests/test_05_tools/test_544_revcloud.py b/tests/test_05_tools/test_544_revcloud.py
index f96d193ab..64997c3d6 100644
--- a/tests/test_05_tools/test_544_revcloud.py
+++ b/tests/test_05_tools/test_544_revcloud.py
@@ -28,13 +28,14 @@ def test_too_small_segment_length_raises_exception():
 def test_add_entity():
     doc = ezdxf.new()
     msp = doc.modelspace()
+    # counter-clockwise oriented revision cloud:
     lwp = revcloud.add_entity(msp, [(0, 0), (1, 0), (1, 1), (0, 1)], 0.1)
 
     assert doc.appids.has_entry(revcloud.REVCLOUD_PROPS)
     assert revcloud.is_revcloud(lwp) is True
 
-    # adding a second revision cloud should be ok:
-    lwp = revcloud.add_entity(msp, [(0, 0), (1, 0), (1, 1), (0, 1)], 0.1)
+    # clockwise oriented revision cloud:
+    lwp = revcloud.add_entity(msp, [(0, 0), (0, 1), (1, 1), (1, 0)], 0.1)
     assert revcloud.is_revcloud(lwp) is True