Created a more accessible way to create Angles with line.py angle function - Angle.from_three_points (#2684)

* fixed style

* fixed style

* fixed formatting

* Update manim/mobject/geometry/line.py

Co-authored-by: Benjamin Hackl <[email protected]>

* Update manim/mobject/geometry/line.py

Co-authored-by: Benjamin Hackl <[email protected]>

* Update manim/mobject/geometry/line.py

Co-authored-by: Benjamin Hackl <[email protected]>

* Update manim/mobject/geometry/line.py

Co-authored-by: Benjamin Hackl <[email protected]>

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* fixed formatting comments and added tests that can visualize graphic better

* Update manim/mobject/geometry/line.py

Co-authored-by: Benjamin Hackl <[email protected]>

* Update manim/mobject/geometry/line.py

Co-authored-by: Benjamin Hackl <[email protected]>

* added additional example

* Update manim/mobject/geometry/line.py

Co-authored-by: Benjamin Hackl <[email protected]>

* Update manim/mobject/geometry/line.py

Co-authored-by: Benjamin Hackl <[email protected]>

* example has been changed!

* fixed name change

* reverted change to not include Vgroup

Co-authored-by: hickmott99 <[email protected]>
Co-authored-by: Benjamin Hackl <[email protected]>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Darylgolden <[email protected]>

Author: 5 people

manim/mobject/geometry/line.py

@@ -1015,6 +1015,46 @@ def construct(self):
             return self.angle_value / DEGREES
         return self.angle_value
 
+    @staticmethod
+    def from_three_points(
+        A: np.ndarray, B: np.ndarray, C: np.ndarray, **kwargs
+    ) -> Angle:
+        """The angle between the lines AB and BC.
+
+        This constructs the angle :math:`\angle ABC`.
+
+        Parameters
+        ----------
+        A
+            The endpoint of the first angle leg
+        B
+            The vertex of the angle
+        C
+            The endpoint of the second angle leg
+
+        **kwargs
+            Further keyword arguments are passed to :class:`.Angle`
+
+        Returns
+        -------
+        The Angle calculated from the three points
+
+                    Angle(line1, line2, radius=0.5, quadrant=(-1,1), stroke_width=8),
+                    Angle(line1, line2, radius=0.7, quadrant=(-1,-1), color=RED, other_angle=True),
+
+        Examples
+        --------
+        .. manim:: AngleFromThreePointsExample
+            :save_last_frame:
+
+            class AngleFromThreePointsExample(Scene):
+                def construct(self):
+                    sample_angle = Angle.from_three_points(UP, ORIGIN, LEFT)
+                    red_angle = Angle.from_three_points(LEFT + UP, ORIGIN, RIGHT, radius=.8, quadrant=(-1,-1), color=RED, stroke_width=8, other_angle=True)
+                    self.add(red_angle, sample_angle)
+        """
+        return Angle(Line(B, A), Line(B, C), **kwargs)
+
 
 class RightAngle(Angle):
     """An elbow-type mobject representing a right angle between two lines.

tests/test_graphical_units/control_data/geometry/three_points_Angle.npz

@@ -168,6 +168,35 @@ def test_Angle(scene):
     scene.add(a)
 
 
+@frames_comparison
+def test_three_points_Angle(scene):
+    # acute angle
+    acute = Angle.from_three_points(
+        np.array([10, 0, 0]), np.array([0, 0, 0]), np.array([10, 10, 0])
+    )
+    # obtuse angle
+    obtuse = Angle.from_three_points(
+        np.array([-10, 1, 0]), np.array([0, 0, 0]), np.array([10, 1, 0])
+    )
+    # quadrant 1 angle
+    q1 = Angle.from_three_points(
+        np.array([10, 10, 0]), np.array([0, 0, 0]), np.array([10, 1, 0])
+    )
+    # quadrant 2 angle
+    q2 = Angle.from_three_points(
+        np.array([-10, 1, 0]), np.array([0, 0, 0]), np.array([-1, 10, 0])
+    )
+    # quadrant 3 angle
+    q3 = Angle.from_three_points(
+        np.array([-10, -1, 0]), np.array([0, 0, 0]), np.array([-1, -10, 0])
+    )
+    # quadrant 4 angle
+    q4 = Angle.from_three_points(
+        np.array([10, -1, 0]), np.array([0, 0, 0]), np.array([1, -10, 0])
+    )
+    scene.add(VGroup(acute, obtuse, q1, q2, q3, q4).arrange(RIGHT))
+
+
 @frames_comparison
 def test_RightAngle(scene):
     l1 = Line(ORIGIN, RIGHT)