Keyframe animation: Camera and opacity

Camera and opacity keyframe animation explained in this tutorial.

import fury
import numpy as np

from fury.animation import Animation, CameraAnimation, Timeline
from fury.animation.interpolator import cubic_spline_interpolator

The Plan

The plan here is to animate (scale and translate) 50 spheres randomly, and show FURY text that appears at the end!

scene = fury.window.Scene()

showm = fury.window.ShowManager(
    scene=scene, size=(900, 768), reset_camera=False, order_transparent=True
)

Creating the main Timeline and adding static actors to it

Here we create a Timeline. so that we can use it as a controller for the 50 animations we will create. So, Instead of updating and adding 50 Animations to the ShowManager, we only need to update the main Timeline. Also, a playback panel can be assigned to this main Timeline.

But, why we need 50 Animations, you may ask. -> A single Animation can handle each property once at a time. So we need 50 Animations to translate and scale our 50 spheres.

playback_panel=True assigns a playback panel that can control the playback of its Animations

timeline = Timeline(playback_panel=True)

Creating two actors for visualization, and to detect camera’s animations.

arrow = fury.actor.arrow(
    np.array([[0, 0, 0]]), np.array([[0, 1, 0]]), np.array([[1, 1, 0]]), scales=5
)
plan = fury.actor.box(
    np.array([[0, 0, 0]]),
    colors=np.array([[1, 1, 1]]),
    scales=np.array([[20, 0.2, 20]]),
)

Creating “FURY” text

fury_text = fury.actor.vector_text(text="FURY", pos=(-4.3, 15, 0), scale=(2, 2, 2))

Creating an Animation to animate the opacity of fury_text

text_anim = Animation(actors=fury_text, loop=False)

opacity is set to 0 at time 29 and set to one at time 35. Linear interpolator is always used by default.

text_anim.set_opacity(29, 0)
text_anim.set_opacity(35, 1)

text_anim contains the text actor is added to the Timeline.

timeline.add_animation(text_anim)

Creating and animating 50 Spheres

for _ in range(50):
    ###########################################################################
    # create a sphere actor that's centered at the origin and has random color
    # and radius.
    actors = [
        fury.actor.sphere(
            np.array([[0, 0, 0]]),
            np.random.random([1, 3]),
            radii=np.random.random([1, 3]),
        )
    ]

    ###########################################################################
    # create a timeline to animate this actor (single actor or list of actors)
    # Actors can be added later using `Timeline.add_actor(actor)`
    animation = Animation(actors=actors)

    # We generate random position and scale values from time=0 to time=49 each
    # two seconds.
    for t in range(0, 50, 2):
        #######################################################################
        # Position and scale are set to a random value at the timestamps
        # mentioned above.
        animation.set_position(t, np.random.random(3) * 30 - np.array([15, 0, 15]))
        animation.set_scale(t, np.repeat(np.random.random(1), 3))

    ###########################################################################
    # change the position interpolator to cubic spline interpolator.
    animation.set_position_interpolator(cubic_spline_interpolator)

    ###########################################################################
    # Finally, the ``Animation`` is added to the ``Timeline``.
    timeline.add_animation(animation)

Animating the camera

Since, only one camera is needed, camera animations are preferably done using a separate Animation. Three properties can control the camera’s animation: Position, focal position (referred to by focal), and up-view.

camera_anim = CameraAnimation(loop=False)
timeline.add_animation(camera_anim)

Multiple keyframes can be set at once as follows. camera focal positions

camera_positions = {
    # time: camera position
    0: np.array([3, 3, 3]),
    4: np.array([50, 25, -40]),
    7: np.array([-50, 50, -40]),
    10: np.array([-25, 25, 20]),
    14: np.array([0, 16, 25]),
    20: np.array([0, 14.5, 20]),
}

# camera focal positions
camera_focal_positions = {
    # time: focal position
    15: np.array([0, 0, 0]),
    20: np.array([3, 9, 5]),
    23: np.array([7, 5, 3]),
    25: np.array([-2, 9, -6]),
    27: np.array([0, 16, 0]),
    31: np.array([0, 14.5, 0]),
}

set_camera_focal can only set one keyframe, but set_camera_focal_keyframes can set a dictionary of keyframes.

camera_anim.set_focal_keyframes(camera_focal_positions)
camera_anim.set_position_keyframes(camera_positions)

Change camera position and focal interpolators

camera_anim.set_position_interpolator(cubic_spline_interpolator)
camera_anim.set_focal_interpolator(cubic_spline_interpolator)

Adding non-animatable actors to the scene.

scene.add(arrow, plan)

Adding the timeline to the ShowManager.

showm.add_animation(timeline)

The ShowManager must go on!

interactive = False

if interactive:
    showm.start()

fury.window.record(
    scene=scene, out_path="viz_keyframe_animation_camera.png", size=(900, 768)
)