Fix percentage distance methods

src/ansys/motorcad/core/geometry.py

@@ -918,51 +918,63 @@
         else:
             raise Exception("Line can only be mirrored about Line()")
 
-    def get_coordinate_from_percentage_distance(self, ref_coordinate, percentage):
-        """Get the coordinate at the percentage distance along the line from the reference.
+    def get_coordinate_from_percentage_distance(self, ref_coordinate, fraction):
+        """Get the coordinate at a fractional distance along the line from the reference coord.
+
+        .. note::
+           This method is deprecated. Use the :func:`Arc.get_coordinate_from_distance`
+           method with the `fraction = ` or `percentage =` argument.
 
         Parameters
         ----------
         ref_coordinate : Coordinate
             Entity reference coordinate.
 
-        percentage : float
-            Percentage distance along Line.
+        fraction : float
+            Fractional distance along Arc.
 
         Returns
         -------
         Coordinate
-            Coordinate at percentage distance along Line.
+            Coordinate at fractional distance along Arc.
         """
-        if ref_coordinate == self.end:
-            coordinate_1 = self.end
-            coordinate_2 = self.start
-        else:
-            coordinate_1 = self.start
-            coordinate_2 = self.end
-
-        t = (self.length * percentage) / self.length
-        x = ((1 - t) * coordinate_1.x) + (t * coordinate_2.x)
-        y = ((1 - t) * coordinate_1.y) + (t * coordinate_2.y)
+        return self.get_coordinate_from_distance(ref_coordinate, fraction=fraction)
 
-        return Coordinate(x, y)
-
-    def get_coordinate_from_distance(self, ref_coordinate, distance):
+    def get_coordinate_from_distance(
+        self, ref_coordinate, distance=None, fraction=None, percentage=None
+    ):
         """Get the coordinate at the specified distance along the line from the reference.
 
         Parameters
         ----------
         ref_coordinate : Coordinate
             Entity reference coordinate.
 
-        distance : float
+        distance : float, optional
             Distance along Line.
 
+        fraction : float, optional
+            Fractional distance along Line.
+
+        percentage : float, optional
+            Percentage distance along Line.
+
         Returns
         -------
         Coordinate
             Coordinate at distance along Line.
         """
+        if not distance:
+            if fraction:
+                distance = self.length * fraction
+                if percentage:
+                    if percentage != fraction * 100:
+                        print("Both fraction and percentage provided. Using fraction.")
+            elif percentage:
+                distance = self.length * (percentage / 100)
+            else:
+                raise Exception("You must provide either a distance, fraction or percentage.")
+
         if ref_coordinate == self.end:
             coordinate_1 = self.end
             coordinate_2 = self.start
@@ -1082,56 +1094,74 @@
         x_shift, y_shift = rt_to_xy(abs(self.radius), angle)
         return Coordinate(self.centre.x + x_shift, self.centre.y + y_shift)
 
-    def get_coordinate_from_percentage_distance(self, ref_coordinate, percentage):
-        """Get the coordinate at the percentage distance along the arc from the reference coord.
+    def get_coordinate_from_percentage_distance(self, ref_coordinate, fraction):
+        """Get the coordinate at a fractional distance along the arc from the reference coord.
+
+        .. note::
+           This method is deprecated. Use the :func:`Arc.get_coordinate_from_distance`
+           method with the `fraction = ` or `percentage =` argument.
 
         Parameters
         ----------
         ref_coordinate : Coordinate
             Entity reference coordinate.
 
-        percentage : float
-            Percentage distance along Arc.
+        fraction : float
+            Fractional distance along Arc.
 
         Returns
         -------
         Coordinate
-            Coordinate at percentage distance along Arc.
+            Coordinate at fractional distance along Arc.
         """
-        length = self.length * percentage
-
-        return self.get_coordinate_from_distance(ref_coordinate, length)
+        return self.get_coordinate_from_distance(ref_coordinate, fraction=fraction)
 
-    def get_coordinate_from_distance(self, ref_coordinate, distance):
+    def get_coordinate_from_distance(
+        self, ref_coordinate, distance=None, fraction=None, percentage=None
+    ):
         """Get the coordinate at the specified distance along the arc from the reference coordinate.
 
         Parameters
         ----------
         ref_coordinate : Coordinate
            Entity reference coordinate.
 
-        distance : float
+        distance : float, optional
             Distance along arc.
 
+        fraction : float, optional
+            Fractional distance along Line.
+
+        percentage : float, optional
+            Percentage distance along Line.
+
         Returns
         -------
         Coordinate
             Coordinate at distance along Arc.
         """
-        if ref_coordinate == self.end:
-            if self.radius >= 0:
-                # anticlockwise
-                angle = atan2(ref_coordinate.y, ref_coordinate.x) - (distance / self.radius)
+        if not distance:
+            if fraction:
+                distance = self.length * fraction
+                if percentage:
+                    if percentage != fraction * 100:
+                        print("Both fraction and percentage provided. Using fraction.")
+            elif percentage:
+                distance = self.length * (percentage / 100)
             else:
-                angle = atan2(ref_coordinate.y, ref_coordinate.x) + (distance / self.radius)
-        else:
-            if self.radius >= 0:
-                # anticlockwise
-                angle = atan2(ref_coordinate.y, ref_coordinate.x) + (distance / self.radius)
-            else:
-                angle = atan2(ref_coordinate.y, ref_coordinate.x) - (distance / self.radius)
+                raise Exception("You must provide either a distance, fraction or percentage.")
 
-        return self.centre + Coordinate(*rt_to_xy(self.radius, degrees(angle)))
+        ref_coordinate_angle = atan2(
+            (ref_coordinate.y - self.centre.y), (ref_coordinate.x - self.centre.x)
+        )
+        if ref_coordinate == self.end:
+            e = -1
+        else:
+            e = 1
+        angle = ref_coordinate_angle + e * (
+            distance / self.radius
+        )  # sign of the radius accounts for clockwise/anticlockwise arcs
+        return self.centre + Coordinate(*rt_to_xy(abs(self.radius), degrees(angle)))
 
     def mirror(self, mirror_line):
         """Mirror arc about a line.
@@ -1164,19 +1194,7 @@
         float
             Length of arc
         """
-        radius, angle_1 = xy_to_rt(self.start.x, self.start.y)
-        radius, angle_2 = xy_to_rt(self.end.x, self.end.y)
-
-        if self.radius == 0:
-            arc_angle = 0
-        elif ((self.radius > 0) and (angle_1 > angle_2)) or (
-            (self.radius < 0) and angle_2 < angle_1
-        ):
-            arc_angle = angle_2 - (angle_1 - 360)
-        else:
-            arc_angle = angle_2 - angle_1
-
-        return self.radius * radians(arc_angle)
+        return abs(self.radius * radians(self.total_angle))
 
     def reverse(self):
         """Reverse Arc entity."""

tests/test_geometry.py

@@ -531,14 +531,31 @@ def test_line_length():
     assert line.length == sqrt(2)
 
 
-def test_arc_get_coordinate_from_percentage_distance():
+def test_arc_get_coordinate_from_fractional_distance():
     arc = geometry.Arc(
         geometry.Coordinate(-1, 0), geometry.Coordinate(1, 0), geometry.Coordinate(0, 0), 1
     )
 
-    coord = arc.get_coordinate_from_percentage_distance(geometry.Coordinate(-1, 0), 0.5)
-    assert isclose(coord.x, 0, abs_tol=1e-12)
-    assert isclose(coord.y, -1, abs_tol=1e-12)
+    coord_1 = arc.get_coordinate_from_percentage_distance(geometry.Coordinate(-1, 0), 0.5)
+    assert isclose(coord_1.x, 0, abs_tol=1e-12)
+    assert isclose(coord_1.y, -1, abs_tol=1e-12)
+
+    # test an arc that failed with the old definition of get_coordinate_from_percentage_distance()
+    arc_2 = geometry.Arc(geometry.Coordinate(62, 20), geometry.Coordinate(56, 33), radius=45)
+    coord_2 = arc_2.get_coordinate_from_percentage_distance(arc_2.end, 1e-13)
+    assert math.isclose(arc_2.end.x, coord_2.x, abs_tol=1e-12)
+    assert math.isclose(arc_2.end.y, coord_2.y, abs_tol=1e-12)
+    coord_3 = arc_2.get_coordinate_from_percentage_distance(arc_2.start, 1e-13)
+    assert math.isclose(arc_2.start.x, coord_3.x, abs_tol=1e-12)
+    assert math.isclose(arc_2.start.y, coord_3.y, abs_tol=1e-12)
+    # test arc drawn clockwise
+    arc_4 = geometry.Arc(geometry.Coordinate(56, 33), geometry.Coordinate(62, 20), radius=45)
+    coord_4 = arc_4.get_coordinate_from_distance(arc_4.end, 1e-13)
+    assert math.isclose(arc_4.end.x, coord_4.x, abs_tol=1e-12)
+    assert math.isclose(arc_4.end.y, coord_4.y, abs_tol=1e-12)
+    coord_5 = arc_4.get_coordinate_from_distance(arc_4.start, 1e-13)
+    assert math.isclose(arc_4.start.x, coord_5.x, abs_tol=1e-12)
+    assert math.isclose(arc_4.start.y, coord_5.y, abs_tol=1e-12)
 
 
 def test_arc_get_coordinate_from_distance():
@@ -550,6 +567,34 @@ def test_arc_get_coordinate_from_distance():
     assert math.isclose(coord.x, 0, abs_tol=1e-12)
     assert math.isclose(coord.y, -1, abs_tol=1e-12)
 
+    # test an arc that failed with the old definition of get_coordinate_from_distance()
+    arc_2 = geometry.Arc(geometry.Coordinate(62, 20), geometry.Coordinate(56, 33), radius=45)
+    coord_2 = arc_2.get_coordinate_from_distance(arc_2.end, 1e-15)
+    assert math.isclose(arc_2.end.x, coord_2.x, abs_tol=1e-12)
+    assert math.isclose(arc_2.end.y, coord_2.y, abs_tol=1e-12)
+    coord_3 = arc_2.get_coordinate_from_distance(arc_2.start, 1e-15)
+    assert math.isclose(arc_2.start.x, coord_3.x, abs_tol=1e-12)
+    assert math.isclose(arc_2.start.y, coord_3.y, abs_tol=1e-12)
+    # test arc drawn clockwise
+    arc_4 = geometry.Arc(geometry.Coordinate(56, 33), geometry.Coordinate(62, 20), radius=45)
+    coord_4 = arc_4.get_coordinate_from_distance(arc_4.end, 1e-15)
+    assert math.isclose(arc_4.end.x, coord_4.x, abs_tol=1e-12)
+    assert math.isclose(arc_4.end.y, coord_4.y, abs_tol=1e-12)
+    coord_5 = arc_4.get_coordinate_from_distance(arc_4.start, 1e-15)
+    assert math.isclose(arc_4.start.x, coord_5.x, abs_tol=1e-12)
+    assert math.isclose(arc_4.start.y, coord_5.y, abs_tol=1e-12)
+    coord_6 = arc_2.get_coordinate_from_distance(arc_2.start, 5)
+    assert math.isclose(60.389142028418, coord_6.x, abs_tol=1e-12)
+    assert math.isclose(24.730689908764, coord_6.y, abs_tol=1e-12)
+
+    coord_7 = arc.get_coordinate_from_distance(geometry.Coordinate(-1, 0), fraction=0.5)
+    assert isclose(coord_7.x, 0, abs_tol=1e-12)
+    assert isclose(coord_7.y, -1, abs_tol=1e-12)
+
+    coord_8 = arc.get_coordinate_from_distance(geometry.Coordinate(-1, 0), percentage=50)
+    assert isclose(coord_8.x, 0, abs_tol=1e-12)
+    assert isclose(coord_8.y, -1, abs_tol=1e-12)
+
 
 def test_arc_length():
     arc = geometry.Arc(