134 lines
5.3 KiB
Python
134 lines
5.3 KiB
Python
"""Manifold explainer 2 — XY pad projects to two numbers.
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A 2-D pad is two independent 0-1 readings. Moving the dot moves A (horizontal)
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and B (vertical) independently, each shown as a slider.
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Render:
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manim -qh s2_xy_pad.py XYPad
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"""
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from manim import *
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BG = "#1C1C1C"
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PRIMARY = "#58C4DD" # pad / control
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A_COL = "#FFFF00" # A axis (horizontal)
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B_COL = "#83C167" # B axis (vertical)
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DIM = 0.4
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MONO = "Monospace"
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def slider(value_tracker, length, colour, horizontal=True):
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"""A track + a knob that tracks value in [0,1] along `length`."""
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if horizontal:
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track = Line(LEFT * length / 2, RIGHT * length / 2, color=colour,
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stroke_width=5).set_opacity(DIM)
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knob = always_redraw(lambda: Dot(
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track.get_start() + RIGHT * value_tracker.get_value() * length,
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radius=0.13, color=colour))
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fill = always_redraw(lambda: Line(
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track.get_start(),
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track.get_start() + RIGHT * value_tracker.get_value() * length,
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color=colour, stroke_width=5))
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else:
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track = Line(DOWN * length / 2, UP * length / 2, color=colour,
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stroke_width=5).set_opacity(DIM)
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knob = always_redraw(lambda: Dot(
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track.get_start() + UP * value_tracker.get_value() * length,
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radius=0.13, color=colour))
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fill = always_redraw(lambda: Line(
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track.get_start(),
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track.get_start() + UP * value_tracker.get_value() * length,
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color=colour, stroke_width=5))
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return VGroup(track), fill, knob
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class XYPad(Scene):
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def construct(self):
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self.camera.background_color = BG
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title = Text("One pad, two numbers", font_size=44, color=PRIMARY,
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weight=BOLD, font=MONO)
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self.play(Write(title), run_time=1.5)
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self.wait(1.0)
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self.play(title.animate.scale(0.62).to_edge(UP, buff=0.5), run_time=1.0)
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self.wait(0.3)
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# the pad
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side = 3.4
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ax = ValueTracker(0.5)
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bx = ValueTracker(0.5)
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pad = Square(side_length=side, color=PRIMARY, stroke_width=5)
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pad.set_fill(PRIMARY, opacity=0.05)
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pad.shift(LEFT * 3.0)
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bl = pad.get_corner(DL)
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grid = VGroup()
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for f in (0.25, 0.5, 0.75):
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grid.add(Line(bl + RIGHT * f * side, bl + RIGHT * f * side + UP * side,
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color=PRIMARY, stroke_width=1).set_opacity(0.15))
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grid.add(Line(bl + UP * f * side, bl + UP * f * side + RIGHT * side,
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color=PRIMARY, stroke_width=1).set_opacity(0.15))
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dot = always_redraw(lambda: Dot(
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bl + RIGHT * ax.get_value() * side + UP * bx.get_value() * side,
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radius=0.13, color=WHITE))
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# guide lines from the dot to each axis
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vline = always_redraw(lambda: DashedLine(
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bl + RIGHT * ax.get_value() * side,
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bl + RIGHT * ax.get_value() * side + UP * bx.get_value() * side,
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color=A_COL, stroke_width=2).set_opacity(DIM))
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hline = always_redraw(lambda: DashedLine(
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bl + UP * bx.get_value() * side,
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bl + RIGHT * ax.get_value() * side + UP * bx.get_value() * side,
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color=B_COL, stroke_width=2).set_opacity(DIM))
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self.play(Create(pad), Create(grid), run_time=1.2)
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self.add(dot)
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pad_label = Text("XY pad", font_size=24, color=PRIMARY, font=MONO)
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pad_label.next_to(pad, DOWN, buff=0.4)
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self.play(FadeIn(pad_label), run_time=0.6)
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self.wait(0.5)
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self.add(vline, hline)
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# A slider (horizontal) and B slider (vertical) on the right
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a_track, a_fill, a_knob = slider(ax, 3.0, A_COL, horizontal=True)
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a_group = VGroup(a_track, a_fill, a_knob)
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a_group.shift(RIGHT * 3.0 + UP * 1.4)
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a_lab = always_redraw(lambda: Text(
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f"A = {ax.get_value():.2f}", font_size=28, color=A_COL, font=MONO
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).next_to(a_track, UP, buff=0.3))
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b_track, b_fill, b_knob = slider(bx, 3.0, B_COL, horizontal=False)
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b_group = VGroup(b_track, b_fill, b_knob)
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b_group.shift(RIGHT * 3.6 + DOWN * 1.4)
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b_lab = always_redraw(lambda: Text(
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f"B = {bx.get_value():.2f}", font_size=28, color=B_COL, font=MONO
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).next_to(b_track, RIGHT, buff=0.4))
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self.play(Create(a_track), Create(b_track), run_time=1.0)
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self.add(a_fill, a_knob, a_lab, b_fill, b_knob, b_lab)
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self.wait(0.5)
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note = Text("A reads across, B reads up -- independently",
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font_size=24, color=WHITE, font=MONO).to_edge(DOWN, buff=0.55)
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self.play(FadeIn(note), run_time=0.8)
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self.wait(1.0)
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# move horizontally only: A changes, B holds
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self.play(ax.animate.set_value(0.9), run_time=1.6, rate_func=smooth)
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self.wait(0.6)
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# move vertically only: B changes, A holds
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self.play(bx.animate.set_value(0.85), run_time=1.6, rate_func=smooth)
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self.wait(0.6)
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# a diagonal sweep: both change together
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self.play(ax.animate.set_value(0.15), bx.animate.set_value(0.2),
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run_time=2.0, rate_func=smooth)
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self.wait(0.6)
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self.play(ax.animate.set_value(0.65), bx.animate.set_value(0.7),
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run_time=1.6, rate_func=smooth)
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self.wait(1.5)
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self.play(FadeOut(Group(*self.mobjects)), run_time=0.6)
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self.wait(0.3)
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