creating metronome animation

This guide walks you through how to generate a looping 3D voxel animation of a metronome using SpatialStudio. The script creates a realistic metronome with a swinging arm, ticking pendulum motion, and musical timing inside a cubic 3D space, then saves the animation to a .splv file.

What this script does

Creates a 3D scene of size 128×128×128
Builds a metronome, complete with:
- A solid wooden base
- A pendulum arm that swings back and forth
- A weighted bob at the end
- Tempo markings on the body
Animates the pendulum swinging rhythmically for 8 seconds at 30 FPS
Outputs the file metronome.splv that you can play in your viewer

How it works (simplified)

Voxel volume Each frame is a 3D grid filled with RGBA values (SIZE × SIZE × SIZE × 4).
Metronome base The body is drawn as a pyramidal wooden structure with a textured brown surface.
Pendulum arm A thin rod that rotates smoothly using sine wave mathematics to create realistic pendulum motion.
Weighted bob A metallic sphere at the end of the arm that follows the pendulum's arc.
Animation loop A normalized time variable t cycles from 0 → 2π, with the pendulum swinging at musical tempo (120 BPM).
Encoding Frames are passed into splv.Encoder, which writes them into the .splv video file.

Try it yourself

Install requirements first:

pip install spatialstudio numpy tqdm

Then copy this script into metronome.py and run:

python metronome.py

Full Script

import numpy as np
from spatialstudio import splv
from tqdm import tqdm

# Scene setup
SIZE, FPS, SECONDS = 128, 30, 8
FRAMES = FPS * SECONDS
CENTER_X = CENTER_Y = CENTER_Z = SIZE // 2
OUT_PATH = "../outputs/metronome.splv"

# Metronome settings
BASE_WIDTH = 20
BASE_HEIGHT = 40
ARM_LENGTH = 35
BOB_RADIUS = 4
SWING_ANGLE = 45  # degrees

def add_voxel(volume, x, y, z, color):
    if 0 <= x < SIZE and 0 <= y < SIZE and 0 <= z < SIZE:
        volume[x, y, z, :3] = color
        volume[x, y, z, 3] = 255

def generate_base(volume, cx, cy, cz, t):
    wood_color = (139, 90, 43)
    # Create pyramidal base
    for y in range(BASE_HEIGHT):
        width_at_height = BASE_WIDTH - (y * BASE_WIDTH // (BASE_HEIGHT * 2))
        for dx in range(-width_at_height, width_at_height + 1):
            for dz in range(-width_at_height, width_at_height + 1):
                # Add wood grain texture
                grain = int(np.sin(y * 0.3 + dx * 0.2) * 10)
                textured_color = tuple(max(20, min(255, c + grain)) for c in wood_color)
                add_voxel(volume, cx + dx, cy - BASE_HEIGHT//2 + y, cz + dz, textured_color)

def generate_tempo_markings(volume, cx, cy, cz):
    marking_color = (50, 50, 50)
    # Add some tempo markings on the front face
    for i in range(5):
        y_pos = cy - BASE_HEIGHT//4 + i * 3
        for x in range(-1, 2):
            add_voxel(volume, cx + BASE_WIDTH//2 - 1, y_pos, cz + x, marking_color)

def generate_pendulum_arm(volume, cx, cy, cz, angle):
    arm_color = (100, 100, 100)  # Metallic gray
    
    # Calculate arm position based on angle
    arm_x = int(ARM_LENGTH * np.sin(np.radians(angle)))
    arm_y_end = cy + BASE_HEIGHT//4
    
    # Draw the arm from pivot point to end
    steps = ARM_LENGTH
    for i in range(steps):
        t_param = i / steps
        x = cx + int(arm_x * t_param)
        y = int(cy + (arm_y_end - cy) * t_param)
        z = cz
        add_voxel(volume, x, y, z, arm_color)
        # Make arm slightly thicker
        add_voxel(volume, x + 1, y, z, arm_color)

def generate_pendulum_bob(volume, cx, cy, cz, angle):
    bob_color = (180, 180, 180)  # Bright metallic
    
    # Calculate bob position
    bob_x = cx + int(ARM_LENGTH * np.sin(np.radians(angle)))
    bob_y = cy + BASE_HEIGHT//4
    
    # Draw spherical bob
    for dx in range(-BOB_RADIUS, BOB_RADIUS + 1):
        for dy in range(-BOB_RADIUS, BOB_RADIUS + 1):
            for dz in range(-BOB_RADIUS, BOB_RADIUS + 1):
                if dx*dx + dy*dy + dz*dz <= BOB_RADIUS*BOB_RADIUS:
                    # Add metallic highlight
                    if dx < 0 and dy > 0:  # Upper left gets highlight
                        highlight_color = (220, 220, 220)
                        add_voxel(volume, bob_x + dx, bob_y + dy, cz + dz, highlight_color)
                    else:
                        add_voxel(volume, bob_x + dx, bob_y + dy, cz + dz, bob_color)

def generate_pivot_point(volume, cx, cy, cz):
    pivot_color = (80, 80, 80)
    pivot_y = cy + BASE_HEIGHT//4
    
    # Small pivot mechanism
    for dx in range(-2, 3):
        for dz in range(-2, 3):
            if dx*dx + dz*dz <= 4:
                add_voxel(volume, cx + dx, pivot_y, cz + dz, pivot_color)

def generate_scene(volume, t):
    # Calculate pendulum angle (120 BPM = 2 Hz)
    angle = SWING_ANGLE * np.sin(t * 4.0)  # 4.0 for 2 complete swings per 2π
    
    generate_base(volume, CENTER_X, CENTER_Y, CENTER_Z, t)
    generate_tempo_markings(volume, CENTER_X, CENTER_Y, CENTER_Z)
    generate_pendulum_arm(volume, CENTER_X, CENTER_Y, CENTER_Z, angle)
    generate_pendulum_bob(volume, CENTER_X, CENTER_Y, CENTER_Z, angle)
    generate_pivot_point(volume, CENTER_X, CENTER_Y, CENTER_Z)

enc = splv.Encoder(SIZE, SIZE, SIZE, framerate=FPS, outputPath=OUT_PATH, motionVectors="off")

for frame in tqdm(range(FRAMES), desc="Generating metronome"):
    volume = np.zeros((SIZE, SIZE, SIZE, 4), dtype=np.uint8)
    t = (frame / FRAMES) * 2*np.pi
    generate_scene(volume, t)
    enc.encode(splv.Frame(volume, lrAxis="x", udAxis="y", fbAxis="z"))

enc.finish()
print(f"Created {OUT_PATH}")

Next steps

Adjust SWING_ANGLE to make the pendulum swing wider or narrower.
Change the timing multiplier in t * 4.0 to speed up or slow down the tempo.
Modify wood_color and bob_color for different materials.
Add a face plate with numbers by expanding the generate_tempo_markings function.
Try adding a subtle "tick" sound visualization with particle effects.

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What this script does

How it works (simplified)

Try it yourself