3D Voxel Cloud Animation Tutorial

This guide walks you through how to generate a looping 3D voxel animation of clouds using SpatialStudio. The script creates realistic, fluffy clouds that drift, morph, and shimmer 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 3 layers of clouds, each with:
- Fluffy, organic cloud formations
- Procedural density variations using noise
- Subtle color gradients from white to gray
- Natural drifting motion
Animates them floating and morphing for 8 seconds at 30 FPS
Outputs the file cloud.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).
Cloud formation Clouds are generated using 3D noise functions that create organic, billowy shapes with varying density.
Layered structure Multiple cloud layers at different heights create depth and realistic cloud coverage.
Color gradients Clouds use white to light gray coloring, with darker areas representing denser cloud material.
Animation loop A normalized time variable t cycles from 0 → 2π, making clouds drift and morph smoothly in a loop.
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 cloud.py and run:

python cloud.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/cloud.splv"

# Cloud settings
CLOUD_LAYERS = 3
CLOUD_DENSITY = 0.4
WIND_SPEED = 0.5
NOISE_SCALE = 0.08

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 noise_3d(x, y, z, scale=1.0, octaves=3):
    """Simple 3D noise function using sine waves"""
    value = 0.0
    amplitude = 1.0
    frequency = scale
    
    for _ in range(octaves):
        value += amplitude * (
            np.sin(x * frequency * 0.1) * 
            np.cos(y * frequency * 0.08) * 
            np.sin(z * frequency * 0.12)
        )
        amplitude *= 0.5
        frequency *= 2.0
    
    return (value + 1.0) * 0.5  # Normalize to 0-1

def generate_cloud_layer(volume, layer_height, t, wind_offset):
    """Generate a single layer of clouds"""
    drift_x = int(t * WIND_SPEED * 10 + wind_offset)
    drift_z = int(t * WIND_SPEED * 8)
    
    for x in range(SIZE):
        for z in range(SIZE):
            # Create cloud base shape
            center_distance = np.sqrt((x - CENTER_X)**2 + (z - CENTER_Z)**2)
            base_height = max(0, 20 - int(center_distance * 0.3))
            
            for y_offset in range(base_height):
                world_x = (x + drift_x) * NOISE_SCALE
                world_y = (layer_height + y_offset) * NOISE_SCALE
                world_z = (z + drift_z) * NOISE_SCALE
                
                # Generate cloud density using noise
                density = noise_3d(world_x, world_y, world_z, 1.0 + t * 0.1, 4)
                density *= noise_3d(world_x * 0.5, world_y * 0.5, world_z * 0.5, 1.0, 2)
                
                # Add some vertical variation
                height_factor = 1.0 - (y_offset / max(1, base_height)) * 0.7
                density *= height_factor
                
                if density > CLOUD_DENSITY:
                    y_pos = layer_height + y_offset
                    if 0 <= y_pos < SIZE:
                        # Color based on density and height
                        brightness = int(255 * (0.7 + density * 0.3))
                        brightness = min(255, max(180, brightness))
                        
                        color = (brightness, brightness, brightness)
                        alpha = int(min(255, density * 400))
                        
                        add_voxel(volume, x, y_pos, z, color, alpha)

def generate_cloud_wisps(volume, t):
    """Add small wispy details to clouds"""
    for i in range(50):  # Number of wisps
        # Random positions that drift over time
        base_x = int((i * 17) % SIZE)
        base_z = int((i * 23) % SIZE)
        base_y = int((i * 13) % 40) + CENTER_Y - 20
        
        drift_x = int(np.sin(t + i * 0.5) * 15)
        drift_y = int(np.sin(t * 0.7 + i * 0.3) * 8)
        drift_z = int(np.cos(t + i * 0.4) * 12)
        
        wisp_x = (base_x + drift_x) % SIZE
        wisp_y = base_y + drift_y
        wisp_z = (base_z + drift_z) % SIZE
        
        # Create small wispy formations
        for dx in range(-3, 4):
            for dy in range(-2, 3):
                for dz in range(-3, 4):
                    distance = np.sqrt(dx*dx + dy*dy + dz*dz)
                    if distance <= 3:
                        noise_val = noise_3d(
                            (wisp_x + dx) * 0.2, 
                            (wisp_y + dy) * 0.2, 
                            (wisp_z + dz) * 0.2
                        )
                        
                        if noise_val > 0.6:
                            x, y, z = wisp_x + dx, wisp_y + dy, wisp_z + dz
                            if 0 <= x < SIZE and 0 <= y < SIZE and 0 <= z < SIZE:
                                color = (240, 240, 245)
                                alpha = int((1.0 - distance/3.0) * 120)
                                add_voxel(volume, x, y, z, color, alpha)

def generate_scene(volume, t):
    """Generate the complete cloud scene"""
    # Generate main cloud layers
    layer_positions = [CENTER_Y - 25, CENTER_Y, CENTER_Y + 20]
    wind_offsets = [0, 50, 100]
    
    for i in range(CLOUD_LAYERS):
        generate_cloud_layer(volume, layer_positions[i], t, wind_offsets[i])
    
    # Add wispy details
    generate_cloud_wisps(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 clouds"):
    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 CLOUD_DENSITY to make clouds thicker or thinner
Change WIND_SPEED to make clouds drift faster or slower
Modify CLOUD_LAYERS to add more depth to your sky
Experiment with different color gradients for sunset or storm clouds
Add lightning effects by occasionally placing bright yellow voxels

Advanced tips

Storm clouds: Use darker grays (100, 100, 120) and increase density
Sunset clouds: Add warm colors (255, 200, 150) to the bottom layers
Morning mist: Use lower cloud layers with higher transparency
Speed up rendering: Reduce SIZE to 64 for faster testing

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