Lights, Camera, Action!

If you have been paying close attention to the video’s output by Algan, then you may have noticed that 3-D objects actually have a sheen, as if being lighted from a light source above.

By default, Algan spawns a light source (of class PointLight ) above and to the the right of the Camera . The Camera itself is spawned at ORIGIN+OUT*7 , and is rotated to look towards the ORIGIN . All 3-D objects (specifically, those inheriting from Surface ), will, at render time, change their color depending on the angle at which rays from the light source hit their surface. This gives the lighting effect you see.

Both the Camera and PointLight are implemented as Mob s, which means you can animate them just as you would any other Mob. You can also add more light sources using SCene.add_light_sources() .

Example: Animating Lights and Camera

Example: LightsAndCameraExample

from algan import *

c1 = GREEN
c2 = RED
mobs = Group([Cylinder(color=c1 * (1-t) + t * c2).rotate(90, OUT) for t in
              torch.linspace(0.,1,9)]).arrange_in_grid(3, buffer=1).scale(0.7).spawn()

r = 5

# Get the active camera used by the scene.
# Now we can animate it just like any other Mob.
camera = Scene.get_camera()

with Sync(run_time=r, rate_func=rate_funcs.identity):
    mobs.rotate(360, RIGHT)
    camera.orbit_around_point(ORIGIN, 360, UP)

# Get the only light source in the scene.
light_source = Scene.get_light_sources()[0]

with Seq(run_time=r):
    light_source.rotate_around_point(ORIGIN, 360, OUT)

# Add a new light source. This one shines BLUE light.
# Make sure to spawn it!
Scene.add_light_source(PointLight(location=ORIGIN + DOWN*10 + OUT * 20,
                                  color=BLUE).spawn())

mobs.wait(r)

render_to_file()

from algan import *

c1 = GREEN
c2 = RED
mobs = Group([Cylinder(color=c1 * (1-t) + t * c2).rotate(90, OUT) for t in
              torch.linspace(0.,1,9)]).arrange_in_grid(3, buffer=1).scale(0.7).spawn()

r = 5

# Get the active camera used by the scene.
# Now we can animate it just like any other Mob.
camera = Scene.get_camera()

with Sync(run_time=r, rate_func=rate_funcs.identity):
    mobs.rotate(360, RIGHT)
    camera.orbit_around_point(ORIGIN, 360, UP)

# Get the only light source in the scene.
light_source = Scene.get_light_sources()[0]

with Seq(run_time=r):
    light_source.rotate_around_point(ORIGIN, 360, OUT)

# Add a new light source. This one shines BLUE light.
# Make sure to spawn it!
Scene.add_light_source(PointLight(location=ORIGIN + DOWN*10 + OUT * 20,
                                  color=BLUE).spawn())

mobs.wait(r)

render_to_file()