3D Voxel Lantern Animation Tutorial

This guide walks you through how to generate a looping 3D voxel animation of lanterns using SpatialStudio. The script creates glowing lanterns that sway gently and emit warm light 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 lanterns, each with:
- A rectangular paper body with traditional patterns
- A metallic top and bottom frame
- A warm, glowing interior light
- Gentle swaying motion
Animates them floating and glowing for 8 seconds at 30 FPS
Outputs the file lanterns.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).
Lantern body Lanterns are drawn as rectangular frames with translucent paper walls and decorative patterns.
Light emission Each lantern contains a warm glowing core that illuminates the surrounding paper walls.
Metal frames Dark metallic caps are added to the top and bottom for authentic lantern appearance.
Animation loop A normalized time variable t cycles from 0 → 2π, creating gentle swaying and light flickering.
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 lanterns.py and run:

python lanterns.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/lanterns.splv"

# Lantern settings
LANTERN_COUNT = 6
LANTERN_WIDTH = 8
LANTERN_HEIGHT = 14
LANTERN_DEPTH = 8

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_lantern_frame(volume, cx, cy, cz, width, height, depth):
    # Metal frame color (dark bronze)
    frame_color = (80, 60, 40)
    
    # Top and bottom frames
    for dx in range(-width//2, width//2 + 1):
        for dz in range(-depth//2, depth//2 + 1):
            add_voxel(volume, cx+dx, cy+height//2, cz+dz, frame_color)
            add_voxel(volume, cx+dx, cy-height//2, cz+dz, frame_color)

def generate_lantern_body(volume, cx, cy, cz, width, height, depth, color, t):
    # Paper lantern walls with patterns
    base_color = color
    
    for y in range(-height//2 + 1, height//2):
        for x in range(-width//2, width//2 + 1):
            for z in range(-depth//2, depth//2 + 1):
                # Create hollow lantern (only walls)
                is_wall = (abs(x) == width//2 or abs(z) == depth//2)
                
                if is_wall:
                    # Add decorative pattern
                    pattern = np.sin(y * 0.5) * np.cos(x * 0.3 + z * 0.3)
                    brightness = 0.8 + 0.2 * pattern
                    
                    # Make paper slightly translucent looking
                    final_color = tuple(int(c * brightness) for c in base_color)
                    add_voxel(volume, cx+x, cy+y, cz+z, final_color)

def generate_inner_light(volume, cx, cy, cz, width, height, depth, t):
    # Warm glowing light inside lantern
    light_colors = [
        (255, 200, 100),  # Warm yellow
        (255, 180, 80),   # Orange glow
        (255, 220, 120),  # Bright yellow
    ]
    
    # Flickering effect
    flicker = 0.8 + 0.2 * np.sin(t * 8 + cx * 0.1)
    
    # Create glowing core
    core_size = 3
    for dx in range(-core_size, core_size + 1):
        for dy in range(-core_size, core_size + 1):
            for dz in range(-core_size, core_size + 1):
                distance = np.sqrt(dx*dx + dy*dy + dz*dz)
                if distance <= core_size:
                    intensity = (1 - distance/core_size) * flicker
                    color_idx = int(intensity * len(light_colors)) % len(light_colors)
                    light_color = light_colors[color_idx]
                    
                    final_color = tuple(int(c * intensity) for c in light_color)
                    if sum(final_color) > 50:  # Only add visible light
                        add_voxel(volume, cx+dx, cy+dy, cz+dz, final_color)

def generate_light_glow(volume, cx, cy, cz, width, height, depth, t):
    # Subtle glow around the lantern
    glow_color = (255, 200, 100)
    flicker = 0.5 + 0.3 * np.sin(t * 6 + cx * 0.15)
    
    for dx in range(-width, width + 1):
        for dy in range(-height//2, height//2 + 1):
            for dz in range(-depth, depth + 1):
                distance = np.sqrt(dx*dx + (dy*0.5)*(dy*0.5) + dz*dz)
                if width + 2 <= distance <= width + 5:
                    intensity = (1 - (distance - width - 2)/3) * 0.3 * flicker
                    if intensity > 0.1:
                        final_color = tuple(int(c * intensity) for c in glow_color)
                        add_voxel(volume, cx+dx, cy+dy, cz+dz, final_color)

def generate_lantern_cluster(volume, cx, cy, cz, t):
    # Lantern paper colors
    paper_colors = [
        (220, 180, 180),  # Soft pink
        (180, 220, 180),  # Soft green
        (180, 180, 220),  # Soft blue
        (220, 220, 180),  # Soft yellow
        (220, 180, 220),  # Soft purple
        (220, 200, 180),  # Soft orange
    ]
    
    for i in range(LANTERN_COUNT):
        # Arrange lanterns in a circle
        angle = (i / LANTERN_COUNT) * 2 * np.pi
        radius = 25
        
        # Gentle swaying motion
        sway_x = np.sin(t * 0.5 + i * 0.7) * 3
        sway_z = np.cos(t * 0.3 + i * 0.5) * 2
        float_y = np.sin(t * 0.8 + i * 0.4) * 4
        
        lx = int(cx + radius * np.cos(angle) + sway_x)
        ly = int(cy + float_y)
        lz = int(cz + radius * np.sin(angle) + sway_z)
        
        # Varying lantern sizes
        scale = 0.8 + 0.4 * np.sin(i * 0.3)
        width = int(LANTERN_WIDTH * scale)
        height = int(LANTERN_HEIGHT * scale)
        depth = int(LANTERN_DEPTH * scale)
        
        color = paper_colors[i % len(paper_colors)]
        
        # Build each lantern
        generate_lantern_frame(volume, lx, ly, lz, width, height, depth)
        generate_lantern_body(volume, lx, ly, lz, width, height, depth, color, t)
        generate_inner_light(volume, lx, ly, lz, width, height, depth, t + i)
        generate_light_glow(volume, lx, ly, lz, width, height, depth, t + i)

def generate_hanging_strings(volume, cx, cy, cz, t):
    string_color = (60, 40, 20)  # Dark brown
    
    for i in range(LANTERN_COUNT):
        angle = (i / LANTERN_COUNT) * 2 * np.pi
        radius = 25
        
        sway_x = np.sin(t * 0.5 + i * 0.7) * 3
        sway_z = np.cos(t * 0.3 + i * 0.5) * 2
        float_y = np.sin(t * 0.8 + i * 0.4) * 4
        
        lx = int(cx + radius * np.cos(angle) + sway_x)
        ly = int(cy + float_y)
        lz = int(cz + radius * np.sin(angle) + sway_z)
        
        # Draw hanging string upward
        string_length = 15
        for j in range(string_length):
            string_sway = np.sin(t * 1.5 + i * 0.5 + j * 0.2) * 2
            sx = lx + int(string_sway)
            sy = ly + LANTERN_HEIGHT//2 + j
            sz = lz
            add_voxel(volume, sx, sy, sz, string_color)

def generate_scene(volume, t):
    generate_lantern_cluster(volume, CENTER_X, CENTER_Y, CENTER_Z, t)
    generate_hanging_strings(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 lanterns"):
    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

Change LANTERN_COUNT to create more lanterns in the scene.
Edit paper_colors to customize the lantern appearances.
Adjust the flicker intensity for different lighting effects.
Modify the radius value to spread lanterns further apart.
Add wind effects by increasing the sway motion parameters.

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