Creating a 3D Voxel Demon Animation

This guide walks you through how to generate a looping 3D voxel animation of a demon using SpatialStudio. The script creates a menacing demon with glowing eyes, flickering horns, and swirling dark energy 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 1 animated demon, featuring:
- A dark red voxel body with muscular definition
- Two curved horns that glow and flicker
- Bright red glowing eyes
- Swirling dark energy particles around the body
Animates the demon with breathing motion and energy effects for 8 seconds at 30 FPS
Outputs the file demon.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).
Demon body The body is constructed using ellipsoids with dark red gradients and surface texturing for a muscular appearance.
Horns Curved horn structures are drawn with procedural mathematics, featuring orange-to-yellow gradient with flickering effects.
Glowing eyes Bright red spherical eyes with white centers that pulse with intensity variations.
Dark energy Swirling particles generated using noise functions that orbit around the demon's body.
Animation loop A normalized time variable t cycles from 0 → 2π, creating breathing motion and energy swirls that loop 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 demon.py and run:

python demon.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/demon.splv"

# Demon settings
DEMON_HEIGHT = 40
DEMON_WIDTH = 20
HORN_LENGTH = 15
EYE_RADIUS = 3
PARTICLE_COUNT = 50

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_demon_body(volume, cx, cy, cz, t):
    # Breathing effect
    breath = 1.0 + 0.1 * np.sin(t * 3.0)
    body_colors = [(120, 20, 20), (80, 10, 10), (60, 5, 5)]
    
    for dy in range(-DEMON_HEIGHT//2, DEMON_HEIGHT//2):
        for dx in range(-DEMON_WIDTH, DEMON_WIDTH+1):
            for dz in range(-DEMON_WIDTH, DEMON_WIDTH+1):
                # Create muscular body shape
                body_radius = DEMON_WIDTH * (1.0 - abs(dy) / (DEMON_HEIGHT/2)) * breath
                torso_width = body_radius * (0.8 + 0.2 * np.sin(dy * 0.2))
                
                if np.sqrt(dx*dx + dz*dz) <= torso_width:
                    # Add surface detail with noise
                    surface_noise = np.sin(dx*0.3 + dy*0.2 + dz*0.4 + t*0.5)
                    muscle_def = int(surface_noise * 2)
                    
                    # Choose color based on depth
                    depth = np.sqrt(dx*dx + dz*dz) / torso_width
                    color_idx = min(2, int(depth * 3))
                    base_color = body_colors[color_idx]
                    
                    # Apply muscle definition
                    brightness = 1.0 + muscle_def * 0.15
                    final_color = tuple(min(255, int(c * brightness)) for c in base_color)
                    
                    add_voxel(volume, cx+dx, cy+dy, cz+dz, final_color)

def generate_horns(volume, cx, cy, cz, t):
    # Flickering horn colors
    flicker = 0.8 + 0.4 * np.sin(t * 8.0)
    horn_color = (int(255 * flicker), int(150 * flicker), int(50 * flicker))
    
    for side in [-1, 1]:  # Left and right horn
        for i in range(HORN_LENGTH):
            progress = i / HORN_LENGTH
            # Curved horn shape
            horn_x = cx + side * (5 + int(progress * 8))
            horn_y = cy - DEMON_HEIGHT//2 + int(progress * 12)
            horn_z = cz - int(progress * 4)
            
            # Horn thickness decreases towards tip
            thickness = max(1, int((1.0 - progress) * 3))
            
            for dx in range(-thickness, thickness+1):
                for dy in range(-thickness, thickness+1):
                    for dz in range(-thickness, thickness+1):
                        if dx*dx + dy*dy + dz*dz <= thickness*thickness:
                            add_voxel(volume, horn_x+dx, horn_y+dy, horn_z+dz, horn_color)

def generate_eyes(volume, cx, cy, cz, t):
    # Pulsing eye glow
    pulse = 0.7 + 0.3 * np.sin(t * 4.0)
    eye_color = (int(255 * pulse), int(50 * pulse), int(50 * pulse))
    eye_center = (255, 255, 255)
    
    for side in [-1, 1]:  # Left and right eye
        eye_x = cx + side * 8
        eye_y = cy - DEMON_HEIGHT//4
        eye_z = cz + DEMON_WIDTH//2
        
        # Eye socket (darker area)
        for dx in range(-EYE_RADIUS-1, EYE_RADIUS+2):
            for dy in range(-EYE_RADIUS-1, EYE_RADIUS+2):
                for dz in range(-EYE_RADIUS-1, EYE_RADIUS+2):
                    if np.sqrt(dx*dx + dy*dy + dz*dz) <= EYE_RADIUS + 1:
                        add_voxel(volume, eye_x+dx, eye_y+dy, eye_z+dz, (40, 0, 0))
        
        # Glowing eye
        for dx in range(-EYE_RADIUS, EYE_RADIUS+1):
            for dy in range(-EYE_RADIUS, EYE_RADIUS+1):
                for dz in range(-EYE_RADIUS, EYE_RADIUS+1):
                    dist = np.sqrt(dx*dx + dy*dy + dz*dz)
                    if dist <= EYE_RADIUS:
                        if dist <= 1:  # Eye center
                            add_voxel(volume, eye_x+dx, eye_y+dy, eye_z+dz, eye_center)
                        else:  # Eye glow
                            add_voxel(volume, eye_x+dx, eye_y+dy, eye_z+dz, eye_color)

def generate_dark_energy(volume, cx, cy, cz, t):
    # Swirling dark energy particles
    energy_color = (100, 0, 100)
    
    for i in range(PARTICLE_COUNT):
        # Create swirling motion
        angle = (i / PARTICLE_COUNT) * 2 * np.pi + t * 2.0
        height_offset = (i / PARTICLE_COUNT) * DEMON_HEIGHT - DEMON_HEIGHT//2
        
        # Spiral parameters
        radius = 25 + 10 * np.sin(t + i * 0.5)
        spiral_height = height_offset + 5 * np.sin(t * 1.5 + i * 0.3)
        
        particle_x = cx + int(radius * np.cos(angle))
        particle_y = cy + int(spiral_height)
        particle_z = cz + int(radius * np.sin(angle))
        
        # Add particle with some randomness
        noise_x = int(3 * np.sin(t * 4 + i))
        noise_z = int(3 * np.cos(t * 3 + i))
        
        # Particle intensity based on position
        intensity = 0.5 + 0.5 * np.sin(t * 3 + i * 0.7)
        final_color = tuple(int(c * intensity) for c in energy_color)
        
        add_voxel(volume, particle_x + noise_x, particle_y, particle_z + noise_z, final_color)

def generate_ground_glow(volume, cx, cy, cz, t):
    # Red glow on the ground around demon's feet
    glow_intensity = 0.3 + 0.2 * np.sin(t * 2.5)
    ground_y = cy + DEMON_HEIGHT//2 + 5
    
    for dx in range(-30, 31):
        for dz in range(-30, 31):
            distance = np.sqrt(dx*dx + dz*dz)
            if distance <= 30:
                brightness = glow_intensity * (1.0 - distance / 30.0)
                glow_color = (int(150 * brightness), int(30 * brightness), int(30 * brightness))
                add_voxel(volume, cx+dx, ground_y, cz+dz, glow_color)

def generate_scene(volume, t):
    generate_ground_glow(volume, CENTER_X, CENTER_Y, CENTER_Z, t)
    generate_dark_energy(volume, CENTER_X, CENTER_Y, CENTER_Z, t)
    generate_demon_body(volume, CENTER_X, CENTER_Y, CENTER_Z, t)
    generate_horns(volume, CENTER_X, CENTER_Y, CENTER_Z, t)
    generate_eyes(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 demon"):
    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 PARTICLE_COUNT to add more or fewer energy particles
Modify horn colors by changing the flicker calculation
Add wing structures using similar ellipsoid techniques
Create multiple demons by calling generate_scene() with different center positions
Experiment with different breathing rates by changing the multiplier in np.sin(t * 3.0)

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