Tornado - 3D Voxel Animation Tutorial

This guide walks you through how to generate a looping 3D voxel animation of a tornado using SpatialStudio. The script creates a swirling tornado with debris particles that spirals and rotates 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 a realistic tornado with:
- A spiraling funnel cloud structure
- Swirling debris particles at different heights
- Dynamic rotation and vertical movement
- Realistic color gradients from dark gray to light dust
Animates the tornado spinning and moving for 8 seconds at 30 FPS
Outputs the file tornado.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).
Tornado funnel The main structure is created using a mathematical spiral that widens from top to bottom, simulating the classic tornado shape.
Particle system Debris particles are generated at various heights and spiral around the tornado's core with realistic physics.
Color gradients The tornado uses different shades - darker grays for the dense core, lighter browns for dust and debris.
Animation loop A normalized time variable t cycles from 0 → 2π, creating smooth rotation and particle movement that loops seamlessly.
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 tornado.py and run:

python tornado.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/tornado.splv"

# Tornado settings
TORNADO_HEIGHT = 60
TORNADO_TOP_RADIUS = 8
TORNADO_BOTTOM_RADIUS = 25
DEBRIS_COUNT = 150
SPIRAL_TIGHTNESS = 0.3

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_tornado_funnel(volume, cx, cy, cz, t):
    # Create the main tornado funnel
    for height in range(TORNADO_HEIGHT):
        # Calculate radius at this height (wider at bottom)
        height_ratio = height / TORNADO_HEIGHT
        radius = TORNADO_TOP_RADIUS + (TORNADO_BOTTOM_RADIUS - TORNADO_TOP_RADIUS) * height_ratio
        
        # Create spiral points around the circumference
        points_per_layer = max(8, int(radius * 2))
        for i in range(points_per_layer):
            angle = (i / points_per_layer) * 2 * np.pi
            spiral_offset = height * SPIRAL_TIGHTNESS + t * 2.0
            
            # Calculate position with spiral effect
            x = cx + int(radius * np.cos(angle + spiral_offset))
            z = cz + int(radius * np.sin(angle + spiral_offset))
            y = cy - int(height * 0.8)  # Tornado extends downward
            
            # Add some turbulence
            turbulence = np.sin(height * 0.1 + t * 3.0 + angle) * 2
            x += int(turbulence)
            z += int(turbulence * 0.5)
            
            # Color varies by height and distance from center
            distance_from_center = np.sqrt((x-cx)**2 + (z-cz)**2)
            density = 1.0 - (distance_from_center / radius) * 0.7
            
            # Darker core, lighter edges
            gray_value = int(60 + 40 * height_ratio + 30 * density)
            color = (gray_value, gray_value - 10, gray_value - 20)
            alpha = int(180 * density)
            
            add_voxel(volume, x, y, z, color, alpha)

def generate_debris(volume, cx, cy, cz, t):
    # Create swirling debris particles
    debris_colors = [
        (101, 67, 33),   # Brown dirt
        (139, 90, 43),   # Light brown
        (160, 82, 45),   # Saddle brown
        (210, 180, 140), # Tan dust
        (112, 128, 144), # Slate gray
    ]
    
    np.random.seed(42)  # Consistent random pattern
    
    for i in range(DEBRIS_COUNT):
        # Each particle has its own orbit parameters
        base_height = np.random.uniform(0, TORNADO_HEIGHT * 0.9)
        orbit_radius = np.random.uniform(5, TORNADO_BOTTOM_RADIUS + 10)
        orbit_speed = np.random.uniform(0.8, 2.5)
        vertical_speed = np.random.uniform(-0.5, 0.5)
        
        # Calculate current position
        angle = (i * 0.3 + t * orbit_speed) % (2 * np.pi)
        current_height = base_height + np.sin(t * vertical_speed + i) * 8
        
        # Position in 3D space
        x = cx + int(orbit_radius * np.cos(angle + current_height * SPIRAL_TIGHTNESS))
        z = cz + int(orbit_radius * np.sin(angle + current_height * SPIRAL_TIGHTNESS))
        y = cy - int(current_height * 0.8)
        
        # Add randomness
        x += int(np.sin(t * 4.0 + i * 0.7) * 3)
        z += int(np.cos(t * 3.5 + i * 0.4) * 3)
        y += int(np.sin(t * 2.0 + i * 0.9) * 2)
        
        # Choose color and size
        color = debris_colors[i % len(debris_colors)]
        particle_size = 1 + (i % 3)  # Vary particle sizes
        
        # Draw particle
        for dx in range(-particle_size, particle_size + 1):
            for dy in range(-particle_size, particle_size + 1):
                for dz in range(-particle_size, particle_size + 1):
                    if dx*dx + dy*dy + dz*dz <= particle_size*particle_size:
                        add_voxel(volume, x+dx, y+dy, z+dz, color)

def generate_ground_dust(volume, cx, cy, cz, t):
    # Add dust clouds near the ground
    dust_y = cy + 20  # Near bottom of scene
    dust_radius = TORNADO_BOTTOM_RADIUS + 15
    
    for i in range(50):
        angle = (i / 50) * 2 * np.pi + t * 1.5
        radius = dust_radius + np.sin(t * 2.0 + i * 0.1) * 8
        
        x = cx + int(radius * np.cos(angle))
        z = cz + int(radius * np.sin(angle))
        y = dust_y + int(np.sin(t * 3.0 + i * 0.2) * 5)
        
        # Light dust color
        dust_color = (194, 178, 128)
        alpha = int(80 + 40 * np.sin(t + i * 0.3))
        
        # Create small dust clouds
        for dx in range(-3, 4):
            for dy in range(-2, 3):
                for dz in range(-3, 4):
                    if dx*dx + dy*dy + dz*dz <= 9:
                        add_voxel(volume, x+dx, y+dy, z+dz, dust_color, alpha)

def generate_scene(volume, t):
    generate_tornado_funnel(volume, CENTER_X, CENTER_Y, CENTER_Z, t)
    generate_debris(volume, CENTER_X, CENTER_Y, CENTER_Z, t)
    generate_ground_dust(volume, CENTER_X, CENTER_Y, CENTER_Z, t)

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

for frame in tqdm(range(FRAMES), desc="Generating tornado"):
    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

Increase DEBRIS_COUNT for more particles in the storm.
Adjust SPIRAL_TIGHTNESS to make the tornado tighter or looser.
Modify TORNADO_HEIGHT and radius values for different tornado sizes.
Add lightning effects by including bright white voxels that flash occasionally.
Experiment with different color palettes for dust storms or water spouts.

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Tornado - 3D Voxel Animation Tutorial

What this script does

How it works (simplified)