Creating 3D Voxel Jellyfish Animation

This guide walks you through how to generate a looping 3D voxel animation of jellyfish using SpatialStudio. The script creates graceful jellyfish that swim, pulse, and glow 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
Spawns 6 jellyfish, each with:
- A translucent bell-shaped body that pulses
- Flowing tentacles that sway naturally
- Bioluminescent glow effects
- Smooth swimming motion through the water
Animates them floating gracefully for 10 seconds at 30 FPS
Outputs the file jellyfish.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).
Jellyfish bell The main body is drawn as a dome with pulsing animation and semi-transparent appearance.
Tentacles Long, flowing appendages that wave and curl using sine functions for natural movement.
Bioluminescence Glowing edges and highlights that pulse with different intensities to simulate underwater lighting.
Swimming motion Each jellyfish follows a unique 3D path with gentle undulating movement.
Animation loop A normalized time variable t cycles from 0 → 2π, ensuring the motion loops smoothly.
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 jellyfish.py and run:

python jellyfish.py

Full Script

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

# Scene setup
SIZE, FPS, SECONDS = 128, 30, 10
FRAMES = FPS * SECONDS
CENTER_X = CENTER_Y = CENTER_Z = SIZE // 2
OUT_PATH = "../outputs/jellyfish.splv"

# Jellyfish settings
JELLYFISH_COUNT = 6
BELL_RADIUS = 12
TENTACLE_COUNT = 8
TENTACLE_LENGTH = 35

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

def generate_bell(volume, cx, cy, cz, color, pulse, t):
    bell_size = int(BELL_RADIUS * (1.0 + pulse * 0.3))
    
    for dx in range(-bell_size, bell_size+1):
        for dy in range(-bell_size//2, bell_size//3+1):
            for dz in range(-bell_size, bell_size+1):
                distance = np.sqrt(dx*dx + dz*dz)
                
                # Create dome shape
                if distance <= bell_size and dy <= 0:
                    height_factor = np.sqrt(max(0, bell_size*bell_size - distance*distance)) / bell_size
                    
                    if dy >= -height_factor * bell_size//2:
                        # Add texture with sine waves
                        texture = np.sin(distance * 0.4 + t * 2.0) * 0.2 + 0.8
                        
                        # Calculate transparency based on distance from center
                        alpha = int(120 + 60 * texture * (1.0 - distance/bell_size))
                        
                        # Adjust color brightness
                        brightness = texture * (0.7 + 0.3 * pulse)
                        final_color = tuple(int(c * brightness) for c in color)
                        
                        add_voxel(volume, cx+dx, cy+dy, cz+dz, final_color, alpha)

def generate_tentacles(volume, cx, cy, cz, color, t, jelly_id):
    for tent_id in range(TENTACLE_COUNT):
        angle = (tent_id / TENTACLE_COUNT) * 2 * np.pi
        
        # Tentacle base position around the bell
        base_radius = BELL_RADIUS * 0.7
        base_x = cx + int(base_radius * np.cos(angle))
        base_z = cz + int(base_radius * np.sin(angle))
        
        # Generate tentacle segments
        for segment in range(TENTACLE_LENGTH):
            progress = segment / TENTACLE_LENGTH
            
            # Create flowing motion
            sway_x = np.sin(t * 1.5 + jelly_id + tent_id * 0.8 + segment * 0.1) * progress * 4
            sway_z = np.cos(t * 1.2 + jelly_id + tent_id * 0.6 + segment * 0.15) * progress * 3
            
            # Tentacle position
            tent_x = base_x + int(sway_x)
            tent_y = cy - BELL_RADIUS//2 - segment
            tent_z = base_z + int(sway_z)
            
            # Tentacle gets thinner towards the tip
            thickness = max(1, int(3 * (1 - progress * 0.8)))
            
            # Add tentacle segments
            for dx in range(-thickness, thickness+1):
                for dz in range(-thickness, thickness+1):
                    if dx*dx + dz*dz <= thickness*thickness:
                        # Darken color towards the tip
                        fade = 1.0 - progress * 0.4
                        tent_color = tuple(int(c * fade) for c in color)
                        alpha = int(180 * fade)
                        
                        add_voxel(volume, tent_x+dx, tent_y, tent_z+dz, tent_color, alpha)

def generate_bioluminescence(volume, cx, cy, cz, pulse, t):
    glow_color = (100, 200, 255)  # Cyan glow
    intensity = int(pulse * 150 + 105)
    
    # Glowing rim around the bell
    for angle in range(0, 360, 15):
        rad = np.radians(angle)
        rim_x = cx + int(BELL_RADIUS * 0.9 * np.cos(rad))
        rim_z = cz + int(BELL_RADIUS * 0.9 * np.sin(rad))
        rim_y = cy - 2
        
        # Add glow with some randomness
        glow_offset = int(np.sin(t * 3 + angle * 0.1) * 2)
        add_voxel(volume, rim_x, rim_y + glow_offset, rim_z, glow_color, intensity)
        
        # Add smaller glow particles
        for i in range(3):
            offset_x = rim_x + np.random.randint(-2, 3)
            offset_y = rim_y + np.random.randint(-1, 2)
            offset_z = rim_z + np.random.randint(-2, 3)
            add_voxel(volume, offset_x, offset_y, offset_z, glow_color, intensity//2)

def generate_jellyfish_swarm(volume, t):
    # Jellyfish colors - various ocean tones
    colors = [
        (180, 120, 200),  # Purple
        (120, 180, 220),  # Light blue
        (200, 150, 100),  # Orange
        (150, 200, 180),  # Mint
        (220, 180, 200),  # Pink
        (140, 160, 200),  # Lavender
    ]
    
    for i in range(JELLYFISH_COUNT):
        # Each jellyfish follows a unique swimming path
        path_offset = (i * 2.1)  # Spread them out in time
        
        # Swimming motion in 3D space
        swim_radius = 25 + 10 * np.sin(i * 0.7)
        swim_x = CENTER_X + int(swim_radius * np.cos(t * 0.4 + path_offset))
        swim_y = CENTER_Y + int(15 * np.sin(t * 0.6 + path_offset)) - 10
        swim_z = CENTER_Z + int(swim_radius * np.sin(t * 0.3 + path_offset))
        
        # Pulsing animation for swimming
        pulse = (np.sin(t * 4.0 + i * 1.2) + 1.0) / 2.0
        
        color = colors[i % len(colors)]
        
        # Generate jellyfish components
        generate_bell(volume, swim_x, swim_y, swim_z, color, pulse, t)
        generate_tentacles(volume, swim_x, swim_y, swim_z, color, t, i)
        generate_bioluminescence(volume, swim_x, swim_y, swim_z, pulse, t)

def add_water_particles(volume, t):
    # Add floating particles to simulate underwater environment
    particle_color = (80, 120, 160)
    
    for i in range(50):
        # Particles drift slowly through the scene
        px = int((SIZE * 0.8) * np.sin(t * 0.2 + i * 0.4) + CENTER_X)
        py = int((SIZE * 0.6) * np.cos(t * 0.15 + i * 0.6) + CENTER_Y)
        pz = int((SIZE * 0.7) * np.sin(t * 0.25 + i * 0.8) + CENTER_Z)
        
        add_voxel(volume, px, py, pz, particle_color, 60)

def generate_scene(volume, t):
    add_water_particles(volume, t)
    generate_jellyfish_swarm(volume, t)

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

# Generate animation frames
for frame in tqdm(range(FRAMES), desc="Generating jellyfish"):
    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 JELLYFISH_COUNT to add more creatures to your underwater scene
Modify the colors array to create different species variations
Change TENTACLE_LENGTH and TENTACLE_COUNT for different jellyfish types
Add + int(t * 10) to Y positions to make jellyfish slowly rise to the surface
Experiment with BELL_RADIUS to create jellyfish of different sizes
Adjust bioluminescence colors for different lighting effects

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