Merge pull request #1181 from nmaslarinos/polyline_extend_shorten_fix

fixed bug in polyline shorten and extend not reseting the lines

Author: tomvanmele

CHANGELOG.md

@@ -232,6 +232,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * Fixed bug in `compas.geometry.angle_vectors_signed`.
 * Fixed bug in `compas.geometry.Polyline.split_at_corners` where angles were sometimes wrongly calculated.
 * Changed `compas.artists.MeshArtist` default colors.
+* Fixed bug in `compas.geometry.curves.Polyline` shorten and extend methods.
 * Changed internal _plane storage of the `compas.datastructures.Halfface` from `_plane[u][v][w]` to `_plane[u][v][fkey]`
 * Fixed `SyntaxError` when importing COMPAS in GHPython.
 

src/compas/geometry/curves/polyline.py

@@ -637,9 +637,11 @@ def extend(self, length):
         try:
             start, end = length
             self.points[0] = self.points[0] + self.lines[0].vector.unitized().scaled(-start)
+            self._lines = None
         except TypeError:
             start = end = length
         self.points[-1] = self.points[-1] + self.lines[-1].vector.unitized().scaled(end)
+        self._lines = None
 
     def extended(self, length):
         """Returns a copy of this polyline extended by a given length.
@@ -701,6 +703,7 @@ def shorten(self, length):
             else:
                 self.points[-1] = line.start + line.vector.unitized().scaled(total_length - end)
                 break
+        self._lines = None
 
     def shortened(self, length):
         """Returns a copy of this polyline shortened by a given length.

tests/compas/geometry/test_curves_polyline.py

@@ -460,54 +460,28 @@ def test_polyline_parameter_at(input, expected):
 
 
 @pytest.mark.parametrize(
-    "coords,input,expected",
+    "coords,input,expected,length",
     [
-        (
-            [[0, 0, 0], [1, 0, 0], [2, 0, 0], [2, 2, 0]],
-            1.5,
-            [[0, 0, 0], [1, 0, 0], [2, 0, 0], [2, 3.5, 0]],
-        ),
-        (
-            [[0, 0, 0], [1, 0, 0], [2, 0, 0], [2, 2, 0]],
-            -2.5,
-            [[0, 0, 0], [1, 0, 0], [2, 0, 0], [2, -0.5, 0]],
-        ),
-        (
-            [[0, 0, 0], [1, 0, 0], [2, 0, 0], [2, 2, 0]],
-            (2, 2),
-            [[-2, 0, 0], [1, 0, 0], [2, 0, 0], [2, 4, 0]],
-        ),
-        (
-            [[0, 0, 0], [1, 0, 0], [2, 0, 0], [2, 2, 0]],
-            (2, 0),
-            [[-2, 0, 0], [1, 0, 0], [2, 0, 0], [2, 2, 0]],
-        ),
+        ([[0, 0, 0], [1, 0, 0], [2, 0, 0], [2, 2, 0]], 1.5, [[0, 0, 0], [1, 0, 0], [2, 0, 0], [2, 3.5, 0]], 5.5),
+        ([[0, 0, 0], [1, 0, 0], [2, 0, 0], [2, 2, 0]], -2.5, [[0, 0, 0], [1, 0, 0], [2, 0, 0], [2, -0.5, 0]], 2.5),
+        ([[0, 0, 0], [1, 0, 0], [2, 0, 0], [2, 2, 0]], (2, 2), [[-2, 0, 0], [1, 0, 0], [2, 0, 0], [2, 4, 0]], 8),
+        ([[0, 0, 0], [1, 0, 0], [2, 0, 0], [2, 2, 0]], (2, 0), [[-2, 0, 0], [1, 0, 0], [2, 0, 0], [2, 2, 0]], 6),
     ],
 )
-def test_polyline_extend(coords, input, expected):
-    assert expected == Polyline(coords).extended(input)
+def test_polyline_extend(coords, input, expected, length):
+    polyline = Polyline(coords).extended(input)
+    assert expected == polyline and length == polyline.length
 
 
 @pytest.mark.parametrize(
-    "coords,input,expected",
+    "coords,input,expected,length",
     [
-        (
-            [[0, 0, 0], [1, 0, 0], [2, 0, 0], [2, 2, 0]],
-            0.5,
-            [[0, 0, 0], [1, 0, 0], [2, 0, 0], [2, 1.5, 0]],
-        ),
-        (
-            [[0, 0, 0], [1, 0, 0], [2, 0, 0], [2, 2, 0]],
-            2,
-            [[0, 0, 0], [1, 0, 0], [2, 0, 0]],
-        ),
-        (
-            [[0, 0, 0], [1, 0, 0], [2, 0, 0], [2, 2, 0]],
-            (0.5, 2.5),
-            [[0.5, 0, 0], [1, 0, 0], [1.5, 0, 0]],
-        ),
-        ([[0, 0, 0], [1, 0, 0], [2, 0, 0], [2, 2, 0]], (1, 2), [[1, 0, 0], [2, 0, 0]]),
+        ([[0, 0, 0], [1, 0, 0], [2, 0, 0], [2, 2, 0]], 0.5, [[0, 0, 0], [1, 0, 0], [2, 0, 0], [2, 1.5, 0]], 3.5),
+        ([[0, 0, 0], [1, 0, 0], [2, 0, 0], [2, 2, 0]], 2, [[0, 0, 0], [1, 0, 0], [2, 0, 0]], 2),
+        ([[0, 0, 0], [1, 0, 0], [2, 0, 0], [2, 2, 0]], (0.5, 2.5), [[0.5, 0, 0], [1, 0, 0], [1.5, 0, 0]], 1),
+        ([[0, 0, 0], [1, 0, 0], [2, 0, 0], [2, 2, 0]], (1, 2), [[1, 0, 0], [2, 0, 0]], 1),
     ],
 )
-def test_polyline_shortened(coords, input, expected):
-    assert expected == Polyline(coords).shortened(input)
+def test_polyline_shortened(coords, input, expected, length):
+    polyline = Polyline(coords).shortened(input)
+    assert expected == polyline and length == polyline.length