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Added some notes to light.py

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Grant Sanderson
2018-02-06 12:51:06 -08:00
parent 58dc8f2f0d
commit cb9e249c6f
1 changed files with 49 additions and 18 deletions
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67
topics/light.py
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@ -42,14 +42,16 @@ inverse_quadratic = lambda maxint,scale,cutoff: inverse_power_law(maxint,scale,c
# Note: Overall, this class seems perfectly reasonable to me, the main
# thing to be wary of is that calling self.add(submob) puts that submob
# at the end of the submobjects list, and hence on top of everything else
# which is why the shadow might sometimes end up behind the spotlight
class LightSource(VMobject):
# combines:
# a lighthouse
# an ambient light
# a spotlight
# and a shadow
CONFIG = {
"source_point": ORIGIN,
"color": LIGHT_COLOR,
@ -115,6 +117,8 @@ class LightSource(VMobject):
if self.has_screen():
self.spotlight.screen = new_screen
else:
# Note: See below
# index = self.submobjects.index(self.spotlight)
self.remove(self.spotlight)
self.spotlight = Spotlight(
source_point = self.source_point,
@ -124,6 +128,13 @@ class LightSource(VMobject):
screen = new_screen
)
self.spotlight.move_source_to(self.source_point)
# Note: This line will make spotlight show up at the end
# of the submojects list, which can make it show up on
# top of the shadow. To make it show up in the
# same spot, you could try the following line,
# where "index" is what I defined above:
# self.submobjects.insert(index, self.spotlight)
self.add(self.spotlight)
# in any case
@ -133,9 +144,12 @@ class LightSource(VMobject):
def move_source_to(self,point):
apoint = np.array(point)
v = apoint - self.source_point
# Note: As discussed, things stand to behave better if source
# point is a submobject, so that it automatically interpolates
# during an animation, and other updates can be defined wrt
# that source point's location
self.source_point = apoint
self.lighthouse.next_to(apoint,DOWN,buff = 0)
self.ambient_light.move_source_to(apoint)
@ -143,12 +157,6 @@ class LightSource(VMobject):
self.spotlight.move_source_to(apoint)
self.update()
return self
def set_radius(self,new_radius):
self.radius = new_radius
@ -169,14 +177,15 @@ class LightSource(VMobject):
for point in self.screen.get_anchors():
projected_screen_points.append(self.spotlight.project(point))
print "projected", self.screen.get_anchors(), "onto", projected_screen_points
# print "projected", self.screen.get_anchors(), "onto", projected_screen_points
projected_source = project_along_vector(self.source_point,self.spotlight.projection_direction())
projected_point_cloud_3d = np.append(projected_screen_points,
np.reshape(projected_source,(1,3)),axis = 0)
projected_point_cloud_3d = np.append(
projected_screen_points,
np.reshape(projected_source,(1,3)),
axis = 0
)
rotation_matrix = z_to_vector(self.spotlight.projection_direction())
back_rotation_matrix = rotation_matrix.T # i. e. its inverse
@ -223,6 +232,9 @@ class LightSource(VMobject):
new_anchors = np.append(new_anchors,anchors[index:],axis = 0)
self.shadow.set_points_as_corners(new_anchors)
# Note: Theoretically this should not be necessary as long as we make
# sure the shadow shows up after the spotlight in the submobjects list.
#
# shift it closer to the camera so it is in front of the spotlight
self.shadow.shift(1e-5*self.spotlight.projection_direction())
self.shadow.mark_paths_closed = True
@ -293,6 +305,10 @@ class AmbientLight(VMobject):
# in theory, this method is only called once, right?
# so removing submobs shd not be necessary
#
# Note: Usually, yes, it is only called within Mobject.__init__,
# but there is no strong guarantee of that, and you may want certain
# update functions to regenerate points here and there.
for submob in self.submobjects:
self.remove(submob)
@ -313,7 +329,7 @@ class AmbientLight(VMobject):
def move_source_to(self,point):
# Note: Best to rewrite in terms of VectorizedPoint source_point
v = np.array(point) - self.source_point
self.source_point = np.array(point)
self.shift(v)
@ -348,6 +364,10 @@ class Spotlight(VMobject):
}
def projection_direction(self):
# Note: This seems reasonable, though for it to work you'd
# need to be sure that any 3d scene including a spotlight
# somewhere assigns that spotlights "camera" attribute
# to be the camera associated with that scene.
if self.camera == None:
return OUT
else:
@ -376,6 +396,10 @@ class Spotlight(VMobject):
def new_sector(self,r,dr,lower_angle,upper_angle):
# Note: I'm not looking _too_ closely at the implementation
# of these updates based on viewing angles and such. It seems to
# behave as intended, but let me know if you'd like more thorough
# scrutiny
alpha = self.max_opacity * self.opacity_function(r)
annular_sector = AnnularSector(
@ -467,13 +491,12 @@ class Spotlight(VMobject):
def dimming(self,new_alpha):
old_alpha = self.max_opacity
self.max_opacity = new_alpha
for submob in self.submobjects:
# Note: Maybe it'd be best to have a Shadow class so that the
# type can be checked directly?
if type(submob) != AnnularSector:
# it's the shadow, don't dim it
continue
@ -498,6 +521,14 @@ class Spotlight(VMobject):
submob.set_fill(opacity = alpha)
# Note: Stylistically, I typically keep all of the implementation for an
# update inside the relevant Animation or ContinualAnimation, rather than
# in the mobject. Things are fine the way you've done it, but sometimes
# I personally like a nice conceptual divide between all the things that
# determine how the mobject is displayed in a single moment (implement in
# the mobject's class itself) and all the things determining how that changes.
#
# Up to you though.
class ScreenTracker(ContinualAnimation):