Create TimeDependentComplexPlane tool for video

To draw a QAM signal we will need a way to plot a time dependent complex
function. So I made a thing that is just a complex plane + a time axis.

1 files changed, 78 insertions, 5 deletions

diff --git a/video/qam.py b/video/qam.py
index 917fdeb..88096e9 100644
--- a/video/qam.py
+++ b/video/qam.py
@@ -1,14 +1,87 @@
 from manimlib import *
+from scipy import signal as sig
 
-class QamModulation(Scene):
+
+class TimeDependentComplexPlane(ComplexPlane):
     CONFIG = {
-        "camera_class": ThreeDCamera,
+        "dimension": 3,
+        "t_range": np.array([0., 5., 1.]),
+        "t_axis_config": {
+            "include_ticks": True,
+        },
+        "background_line_style": {
+            "stroke_color": GREY_D,
+        },
+        "depth": 8,
     }
 
+    def __init__(self, **kwargs):
+        ComplexPlane.__init__(self, **kwargs)
+
+        t_axis = self.create_axis(self.t_range, self.t_axis_config, self.depth)
+        t_axis.rotate(-PI / 2, UP, about_point=ORIGIN)
+        t_axis.shift(self.n2p(0))
+
+        self.t_axis = t_axis
+        self.add(t_axis)
+        self.axes.add(t_axis)
+
+    def number_to_point(self, number, time=0):
+        return self.coords_to_point(number.real, number.imag, time)
+
+    def n2p(self, number, time=0):
+        return self.number_to_point(number, time)
+
+    def get_t_axis(self):
+        return self.axes[2]
+
+    def get_graph(self, function, axis, t_range=None, **kwargs):
+        # sample range
+        s_range = np.array(self.t_range, dtype=float)
+
+        if t_range is not None:
+            s_range[:len(t_range)] = t_range
+
+        if t_range is None or len(t_range) < 3:
+            s_range[2] /= self.num_sampled_graph_points_per_tick
+
+        graph = ParametricCurve(
+            lambda t: self.t_axis.number_to_point(t) + axis.number_to_point(function(t)),
+            t_range=s_range,
+            **kwargs
+        )
+        graph.underlying_function = function
+        graph.t_range = t_range
+        return graph
+
+    def get_inphase_graph(self, function, **kwargs):
+        return self.get_graph(function, self.get_x_axis(), **kwargs)
+
+    def get_quadrature_graph(self, function, **kwargs):
+        return self.get_graph(function, self.get_y_axis(), **kwargs)
+
+
+class QamModulation(Scene):
+    CONFIG = {}
+
     def construct(self):
-        circle = Circle()
-        self.play(FadeIn(circle))
-        self.wait(3)
+        cplane = TimeDependentComplexPlane()
+
+        self.play(ShowCreation(cplane))
+        self.play(self.camera.frame.animate.move_to(2 * OUT))
+
+        graph_y = cplane.get_inphase_graph(lambda t: 2 * np.cos(2 * t), color=RED)
+        graph_x = cplane.get_quadrature_graph(lambda t: 1 * sig.square(4 * t), color=BLUE)
+
+        self.play(self.camera.frame.animate.reorient(90, 90, 90))
+        self.play(ShowCreation(graph_x))
+
+        self.play(self.camera.frame.animate.reorient(0, 90, 90))
+        self.play(ShowCreation(graph_y))
+
+        self.play(self.camera.frame.animate.reorient(80, 90, 90))
+
+        # arrow = Arrow(
 
         # open an interactive IPython shell here
         self.embed()