Preliminary Lens, Mirror and Glass scenes established

This commit is contained in:
Grant Sanderson 2016-02-15 23:42:46 -08:00
parent 044e0b5c72
commit 601abf18f3

View file

@ -49,7 +49,9 @@ class Lens(Arc):
class PhotonScene(Scene):
def wavify(self, mobject):
tangent_vectors = mobject.points[1:]-mobject.points[:-1]
result = mobject.copy()
result.ingest_sub_mobjects()
tangent_vectors = result.points[1:]-result.points[:-1]
lengths = np.apply_along_axis(
np.linalg.norm, 1, tangent_vectors
)
@ -62,7 +64,6 @@ class PhotonScene(Scene):
nudge_sizes = 0.1*np.sin(2*np.pi*times)
thick_nudge_sizes = nudge_sizes.repeat(3).reshape((len(nudge_sizes), 3))
nudges = thick_nudge_sizes*normal_vectors
result = mobject.copy()
result.points[1:] += nudges
return result
@ -84,29 +85,12 @@ class SimplePhoton(PhotonScene):
self.dither()
class PhotonThroughLens(PhotonScene):
def construct(self):
lens = Lens()
num_paths = 5
interval_values = np.arange(num_paths)/(num_paths-1.)
first_contact = [
lens.point_from_interval(0.4*v+0.55)
for v in reversed(interval_values)
]
second_contact = [
lens.point_from_interval(0.3*v + 0.1)
for v in interval_values
]
focal_point = 2*RIGHT
paths = [
Mobject(
Line(SPACE_WIDTH*LEFT + fc[1]*UP, fc),
Line(fc, sc),
Line(sc, focal_point),
Line(focal_point, 6*focal_point-5*sc)
).ingest_sub_mobjects()
for fc, sc in zip(first_contact, second_contact)
]
class MultipathPhotonScene(PhotonScene):
DEFAULT_CONFIG = {
"num_paths" : 5
}
def run_along_paths(self):
paths = self.get_paths()
colors = Color(YELLOW).range_to(WHITE, len(paths))
for path, color in zip(paths, colors):
path.highlight(color)
@ -114,7 +98,6 @@ class PhotonThroughLens(PhotonScene):
self.photon_run_along_path(path)
for path in paths
]
self.add(lens)
for photon_run, path in zip(photon_runs, paths):
self.play(
photon_run,
@ -125,7 +108,202 @@ class PhotonThroughLens(PhotonScene):
)
self.dither()
def generate_paths(self):
raise Exception("Not Implemented")
class PhotonThroughLens(MultipathPhotonScene):
def construct(self):
self.lens = Lens()
self.add(self.lens)
self.run_along_paths()
def get_paths(self):
interval_values = np.arange(self.num_paths).astype('float')
interval_values /= (self.num_paths-1.)
first_contact = [
self.lens.point_from_proportion(0.4*v+0.55)
for v in reversed(interval_values)
]
second_contact = [
self.lens.point_from_proportion(0.3*v + 0.1)
for v in interval_values
]
focal_point = 2*RIGHT
return [
Mobject(
Line(SPACE_WIDTH*LEFT + fc[1]*UP, fc),
Line(fc, sc),
Line(sc, focal_point),
Line(focal_point, 6*focal_point-5*sc)
).ingest_sub_mobjects()
for fc, sc in zip(first_contact, second_contact)
]
class PhotonOffMirror(MultipathPhotonScene):
def construct(self):
self.mirror = Line(*SPACE_HEIGHT*np.array([DOWN, UP]))
self.mirror.highlight(GREY)
self.add(self.mirror)
self.run_along_paths()
def get_paths(self):
interval_values = np.arange(self.num_paths).astype('float')
interval_values /= (self.num_paths-1)
anchor_points = [
self.mirror.point_from_proportion(0.6*v+0.3)
for v in interval_values
]
start_point = 5*LEFT+3*UP
end_points = []
for point in anchor_points:
vect = start_point-point
vect[1] *= -1
end_points.append(point+2*vect)
return [
Mobject(
Line(start_point, anchor_point),
Line(anchor_point, end_point)
).ingest_sub_mobjects()
for anchor_point, end_point in zip(anchor_points, end_points)
]
class PhotonsInGlass(MultipathPhotonScene):
def construct(self):
glass = Region(lambda x, y : y < 0)
self.highlight_region(glass, BLUE_E)
self.run_along_paths()
def get_paths(self):
x, y = -3, 3
start_point = x*RIGHT + y*UP
angles = np.arange(np.pi/18, np.pi/3, np.pi/18)
midpoints = y*np.arctan(angles)
end_points = midpoints + SPACE_HEIGHT*np.arctan(2*angles)
return [
Mobject(
Line(start_point, [midpoint, 0, 0]),
Line([midpoint, 0, 0], [end_point, -SPACE_HEIGHT, 0])
).ingest_sub_mobjects()
for midpoint, end_point in zip(midpoints, end_points)
]
class ShowMultiplePathsScene(PhotonScene):
def construct(self):
text = TextMobject("Which path minimizes travel time?")
text.to_edge(UP)
self.generate_start_and_end_points()
point_a = Dot(self.start_point)
point_b = Dot(self.end_point)
A = TextMobject("A").next_to(point_a, UP)
B = TextMobject("B").next_to(point_b, DOWN)
paths = self.get_paths()
for point, letter in [(point_a, A), (point_b, B)]:
self.play(
ShowCreation(point),
ShimmerIn(letter)
)
self.play(ShimmerIn(text))
curr_path = paths[0].copy()
curr_path_copy = curr_path.copy().ingest_sub_mobjects()
self.play(
self.photon_run_along_path(curr_path),
ShowCreation(curr_path_copy, rate_func = rush_into)
)
self.remove(curr_path_copy)
for path in paths[1:] + [paths[0]]:
self.play(Transform(curr_path, path, run_time = 4))
self.dither()
def generate_start_and_end_points(self):
raise Exception("Not Implemented")
def get_paths(self):
raise Exception("Not implemented")
class ShowMultiplePathsThroughLens(ShowMultiplePathsScene):
def construct(self):
self.lens = Lens()
self.add(self.lens)
ShowMultiplePathsScene.construct(self)
def generate_start_and_end_points(self):
self.start_point = 3*LEFT + UP
self.end_point = 2*RIGHT
def get_paths(self):
alphas = [0.2, 0.45, 0.55, 0.8]
lower_right, upper_right, upper_left, lower_left = map(
self.lens.point_from_proportion, alphas
)
return [
Mobject(
Line(self.start_point, a),
Line(a, b),
Line(b, self.end_point)
).highlight(color)
for (a, b), color in zip(
[
(upper_left, upper_right),
(upper_left, lower_right),
(lower_left, lower_right),
(lower_left, upper_right),
],
Color(YELLOW).range_to(WHITE, 4)
)
]
class ShowMultiplePathsOffMirror(ShowMultiplePathsScene):
def construct(self):
mirror = Line(*SPACE_HEIGHT*np.array([DOWN, UP]))
mirror.highlight(GREY)
self.add(mirror)
ShowMultiplePathsScene.construct(self)
def generate_start_and_end_points(self):
self.start_point = 4*LEFT + 2*UP
self.end_point = 4*LEFT + 2*DOWN
def get_paths(self):
return [
Mobject(
Line(self.start_point, midpoint),
Line(midpoint, self.end_point)
).highlight(color)
for midpoint, color in zip(
[2*UP, 2*DOWN],
Color(YELLOW).range_to(WHITE, 2)
)
]
class ShowMultiplePathsInGlass(ShowMultiplePathsScene):
def construct(self):
glass = Region(lambda x, y : y < 0)
self.highlight_region(glass, BLUE_E)
ShowMultiplePathsScene.construct(self)
def generate_start_and_end_points(self):
self.start_point = 3*LEFT + 2*UP
self.end_point = 3*RIGHT + 2*DOWN
def get_paths(self):
return [
Mobject(
Line(self.start_point, midpoint),
Line(midpoint, self.end_point)
).highlight(color)
for midpoint, color in zip(
[3*LEFT, 3*RIGHT],
Color(YELLOW).range_to(WHITE, 2)
)
]