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Updates to VectorField

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This commit is contained in:
Grant Sanderson 2021-03-18 17:34:16 -07:00
parent 3c240478b8
commit ed2e3e80d9
1 changed files with 23 additions and 12 deletions
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35
manimlib/mobject/vector_field.py
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@ -62,10 +62,13 @@ def move_submobjects_along_vector_field(mobject, func):
return mobject return mobject
def move_points_along_vector_field(mobject, func): def move_points_along_vector_field(mobject, func, coordinate_system):
cs = coordinate_system
origin = cs.get_origin()
def apply_nudge(self, dt): def apply_nudge(self, dt):
self.mobject.apply_function( mobject.apply_function(
lambda p: p + func(p) * dt lambda p: p + (cs.c2p(*func(*cs.p2c(p))) - origin) * dt
) )
mobject.add_updater(apply_nudge) mobject.add_updater(apply_nudge)
return mobject return mobject
@ -162,19 +165,21 @@ class StreamLines(VGroup):
self.init_style() self.init_style()
def point_func(self, point): def point_func(self, point):
return self.coordinate_system.c2p( in_coords = self.coordinate_system.p2c(point)
*self.func(*self.coordinate_system.p2c(point)) out_coords = self.func(*in_coords)
) return self.coordinate_system.c2p(*out_coords)
def draw_lines(self): def draw_lines(self):
lines = [] lines = []
origin = self.coordinate_system.get_origin()
for point in self.get_start_points(): for point in self.get_start_points():
points = [point] points = [point]
total_arc_len = 0 total_arc_len = 0
# for t in np.arange(0, self.virtual_time, self.dt): time = 0
for x in range(self.max_time_steps): for x in range(self.max_time_steps):
time += self.dt
last_point = points[-1] last_point = points[-1]
new_point = last_point + self.dt * self.point_func(last_point) new_point = last_point + self.dt * (self.point_func(last_point) - origin)
points.append(new_point) points.append(new_point)
total_arc_len += get_norm(new_point - last_point) total_arc_len += get_norm(new_point - last_point)
if get_norm(last_point) > self.cutoff_norm: if get_norm(last_point) > self.cutoff_norm:
@ -182,8 +187,10 @@ class StreamLines(VGroup):
if total_arc_len > self.arc_len: if total_arc_len > self.arc_len:
break break
line = VMobject() line = VMobject()
line.virtual_time = time
step = max(1, int(len(points) / self.n_samples_per_line)) step = max(1, int(len(points) / self.n_samples_per_line))
line.set_points_smoothly(points[::step]) line.set_points_as_corners(points[::step])
line.make_approximately_smooth()
lines.append(line) lines.append(line)
self.set_submobjects(lines) self.set_submobjects(lines)
@ -220,7 +227,7 @@ class StreamLines(VGroup):
rgbas[:, 3] = self.stroke_opacity rgbas[:, 3] = self.stroke_opacity
line.set_rgba_array(rgbas, "stroke_rgba") line.set_rgba_array(rgbas, "stroke_rgba")
else: else:
self.set_stroke(self.stroke_color) self.set_stroke(self.stroke_color, opacity=self.stroke_opacity)
if self.taper_stroke_width: if self.taper_stroke_width:
width = [0, self.stroke_width, 0] width = [0, self.stroke_width, 0]
@ -234,7 +241,7 @@ class AnimatedStreamLines(VGroup):
"lag_range": 4, "lag_range": 4,
"line_anim_class": VShowPassingFlash, "line_anim_class": VShowPassingFlash,
"line_anim_config": { "line_anim_config": {
"run_time": 4, # "run_time": 4,
"rate_func": linear, "rate_func": linear,
"time_width": 0.5, "time_width": 0.5,
}, },
@ -244,7 +251,11 @@ class AnimatedStreamLines(VGroup):
super().__init__(**kwargs) super().__init__(**kwargs)
self.stream_lines = stream_lines self.stream_lines = stream_lines
for line in stream_lines: for line in stream_lines:
line.anim = self.line_anim_class(line, **self.line_anim_config) line.anim = self.line_anim_class(
line,
run_time=line.virtual_time,
**self.line_anim_config,
)
line.anim.begin() line.anim.begin()
line.time = -self.lag_range * random.random() line.time = -self.lag_range * random.random()
self.add(line.anim.mobject) self.add(line.anim.mobject)