Castle 3D Voxel Animation Tutorial

This guide walks you through how to generate a looping 3D voxel animation of a medieval castle using SpatialStudio. The script creates a detailed castle with towers, walls, and animated elements like flags and torch flames 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
Builds a medieval castle with:
- Multiple stone towers with crenellations
- Connecting walls and a main gate
- Animated flags waving in the wind
- Flickering torch flames
- A textured stone foundation
Animates the flags and flames for 10 seconds at 30 FPS
Outputs the file castle.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).
Castle structure The castle is built from gray stone blocks arranged in towers, walls, and battlements with realistic proportions.
Animated flags Colorful banners are placed on tower tops with sine-wave animations to simulate wind movement.
Torch flames Orange and yellow flame voxels flicker randomly on castle walls using noise functions.
Stone texture Subtle variations in gray tones create realistic stone texture using perlin-like noise.
Animation loop A normalized time variable t cycles from 0 → 2π, ensuring smooth looping animations.
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 castle.py and run:

python castle.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/castle.splv"

# Castle settings
TOWER_HEIGHT = 35
WALL_HEIGHT = 20
FOUNDATION_HEIGHT = 5
TOWER_RADIUS = 8
WALL_THICKNESS = 4

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 get_stone_color(x, y, z, base_color=(120, 120, 120)):
    noise = np.sin(x*0.1) * np.sin(y*0.15) * np.sin(z*0.12)
    variation = int(noise * 15)
    return tuple(max(60, min(180, c + variation)) for c in base_color)

def generate_foundation(volume, cx, cy, cz):
    for dx in range(-45, 46):
        for dz in range(-45, 46):
            for dy in range(FOUNDATION_HEIGHT):
                if abs(dx) <= 42 and abs(dz) <= 42:
                    color = get_stone_color(cx+dx, cy-dy, cz+dz, (100, 90, 80))
                    add_voxel(volume, cx+dx, cy-dy, cz+dz, color)

def generate_tower(volume, cx, cy, cz, radius, height):
    for dy in range(height):
        for dx in range(-radius, radius+1):
            for dz in range(-radius, radius+1):
                dist = np.sqrt(dx*dx + dz*dz)
                if dist <= radius:
                    # Hollow tower interior
                    if dist > radius-2 or dy < 3:
                        color = get_stone_color(cx+dx, cy+dy, cz+dz)
                        add_voxel(volume, cx+dx, cy+dy, cz+dz, color)
    
    # Add crenellations (castle battlements)
    for angle in range(0, 360, 30):
        rad = np.radians(angle)
        bx = cx + int((radius-1) * np.cos(rad))
        bz = cz + int((radius-1) * np.sin(rad))
        for dy in range(3):
            color = get_stone_color(bx, cy+height+dy, bz)
            add_voxel(volume, bx, cy+height+dy, bz, color)

def generate_wall(volume, x1, y, z1, x2, z2, height, thickness):
    steps = max(abs(x2-x1), abs(z2-z1))
    if steps == 0:
        return
    
    for i in range(steps+1):
        t = i / steps if steps > 0 else 0
        x = int(x1 + (x2-x1) * t)
        z = int(z1 + (z2-z1) * t)
        
        for dy in range(height):
            for thick in range(thickness):
                # Add thickness perpendicular to wall direction
                if abs(x2-x1) > abs(z2-z1):  # Horizontal wall
                    wall_z = z + thick - thickness//2
                    color = get_stone_color(x, y+dy, wall_z)
                    add_voxel(volume, x, y+dy, wall_z, color)
                else:  # Vertical wall
                    wall_x = x + thick - thickness//2
                    color = get_stone_color(wall_x, y+dy, z)
                    add_voxel(volume, wall_x, y+dy, z, color)

def generate_gate(volume, cx, cy, cz):
    # Create arched gate entrance
    for dx in range(-4, 5):
        for dy in range(8):
            if abs(dx) <= 3 and dy < 6:
                # Arch shape
                if dy < 4 or abs(dx) <= 2:
                    add_voxel(volume, cx+dx, cy+dy, cz, (50, 30, 20))  # Dark gate

def generate_flag(volume, cx, cy, cz, t, flag_id):
    colors = [(200, 0, 0), (0, 150, 200), (200, 200, 0), (150, 0, 200)]
    flag_color = colors[flag_id % len(colors)]
    
    # Flag pole
    for dy in range(8):
        add_voxel(volume, cx, cy+dy, cz, (101, 67, 33))
    
    # Animated flag
    wave_offset = np.sin(t * 3.0 + flag_id * 0.5) * 2
    for fx in range(6):
        for fy in range(4):
            wave = int(np.sin((fx * 0.5 + t * 2.0) + flag_id) * 1.5)
            flag_x = cx + 1 + fx
            flag_y = cy + 5 + fy
            flag_z = cz + wave + int(wave_offset)
            add_voxel(volume, flag_x, flag_y, flag_z, flag_color)

def generate_torch_flame(volume, cx, cy, cz, t):
    # Torch post
    for dy in range(4):
        add_voxel(volume, cx, cy-dy, cz, (101, 67, 33))
    
    # Flickering flame
    flame_height = 3 + int(np.sin(t * 8.0 + cx * 0.1) * 1.5)
    for dy in range(flame_height):
        flicker = int(np.sin(t * 10.0 + dy * 0.3 + cx * 0.05) * 1.5)
        for dx in range(-1, 2):
            for dz in range(-1, 2):
                if abs(dx) + abs(dz) <= 1:
                    # Color gradient from yellow to orange to red
                    if dy < flame_height // 2:
                        color = (255, 200, 50)  # Yellow core
                    elif dy < flame_height * 0.75:
                        color = (255, 120, 20)  # Orange
                    else:
                        color = (220, 50, 20)   # Red tips
                    
                    flame_x = cx + dx + flicker
                    flame_y = cy + dy
                    flame_z = cz + dz
                    add_voxel(volume, flame_x, flame_y, flame_z, color)

def generate_castle(volume, cx, cy, cz, t):
    # Foundation
    generate_foundation(volume, cx, cy, cz)
    
    # Corner towers
    tower_positions = [(-25, -25), (25, -25), (25, 25), (-25, 25)]
    for i, (tx, tz) in enumerate(tower_positions):
        generate_tower(volume, cx+tx, cy, cz+tz, TOWER_RADIUS, TOWER_HEIGHT)
        # Add flags to towers
        generate_flag(volume, cx+tx+TOWER_RADIUS-2, cy+TOWER_HEIGHT, cz+tz, t, i)
    
    # Central keep (main tower)
    generate_tower(volume, cx, cy, cz, TOWER_RADIUS+2, TOWER_HEIGHT+8)
    generate_flag(volume, cx+TOWER_RADIUS, cy+TOWER_HEIGHT+8, cz, t, 4)
    
    # Connecting walls
    wall_y = cy + FOUNDATION_HEIGHT
    generate_wall(volume, cx-25, wall_y, cz-25, cx+25, cz-25, WALL_HEIGHT, WALL_THICKNESS)  # Front
    generate_wall(volume, cx+25, wall_y, cz-25, cx+25, cz+25, WALL_HEIGHT, WALL_THICKNESS)  # Right
    generate_wall(volume, cx+25, wall_y, cz+25, cx-25, cz+25, WALL_HEIGHT, WALL_THICKNESS)  # Back
    generate_wall(volume, cx-25, wall_y, cz+25, cx-25, cz-25, WALL_HEIGHT, WALL_THICKNESS)  # Left
    
    # Main gate
    generate_gate(volume, cx, cy+FOUNDATION_HEIGHT, cz-25)
    
    # Torches on walls
    torch_positions = [(cx-15, cz-23), (cx+15, cz-23), (cx+23, cz-15), (cx+23, cz+15)]
    for tx, tz in torch_positions:
        generate_torch_flame(volume, tx, wall_y+WALL_HEIGHT+2, tz, t)

def generate_scene(volume, t):
    generate_castle(volume, CENTER_X, CENTER_Y-20, CENTER_Z, t)

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

for frame in tqdm(range(FRAMES), desc="Building castle"):
    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 TOWER_HEIGHT and TOWER_RADIUS for different castle proportions
Change flag colors by modifying the colors array in generate_flag()
Add more towers by extending the tower_positions list
Experiment with different stone textures in get_stone_color()
Add a moat by creating water voxels around the foundation
Increase SECONDS for longer animations or add day/night cycles

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Castle 3D Voxel Animation Tutorial

What this script does

How it works (simplified)