Crystal - 3D Voxel Animation Tutorial

This guide walks you through how to generate a looping 3D voxel animation of crystals using SpatialStudio. The script creates sparkling crystal formations that grow, rotate, and emit magical particles 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 crystal formations, each with:
- A geometric crystal body with multiple facets
- Rotating inner core with prismatic colors
- Sparkling particle effects around the base
- Dynamic light rays emanating from the tips
Animates them growing and pulsing for 8 seconds at 30 FPS
Outputs the file crystal.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).
Crystal structure Crystals are drawn as multi-sided geometric shapes with sharp edges and faceted surfaces.
Inner core Each crystal gets a rotating prismatic core that cycles through rainbow colors.
Particle effects Tiny glowing particles swirl around the crystal base, creating a magical atmosphere.
Light rays Bright beams of light shoot upward from crystal tips, with intensity that pulses over time.
Animation loop A normalized time variable t cycles from 0 → 2π, ensuring the motion loops 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 crystal.py and run:

python crystal.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/crystal.splv"

# Crystal settings
CRYSTAL_COUNT = 6
CRYSTAL_HEIGHT = 20
CRYSTAL_BASE_RADIUS = 6
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 hsv_to_rgb(h, s, v):
    """Convert HSV color to RGB"""
    c = v * s
    x = c * (1 - abs((h / 60) % 2 - 1))
    m = v - c
    
    if h < 60:
        r, g, b = c, x, 0
    elif h < 120:
        r, g, b = x, c, 0
    elif h < 180:
        r, g, b = 0, c, x
    elif h < 240:
        r, g, b = 0, x, c
    elif h < 300:
        r, g, b = x, 0, c
    else:
        r, g, b = c, 0, x
    
    return (int((r + m) * 255), int((g + m) * 255), int((b + m) * 255))

def generate_crystal_body(volume, cx, cy, cz, base_color, height, t, crystal_id):
    # Crystal grows over time
    growth = 0.7 + 0.3 * np.sin(t * 0.5 + crystal_id * 0.8)
    actual_height = int(height * growth)
    
    for y in range(actual_height):
        # Crystal tapers toward the top
        progress = y / actual_height
        radius = CRYSTAL_BASE_RADIUS * (1 - progress * 0.8)
        
        # Create faceted sides (hexagonal cross-section)
        for angle_step in range(6):
            angle = (angle_step / 6.0) * 2 * np.pi + t * 0.2
            
            # Create each face of the crystal
            for r in range(int(radius)):
                face_x = int(r * np.cos(angle))
                face_z = int(r * np.sin(angle))
                
                # Add some geometric variation
                if r == int(radius) - 1:  # Edge highlights
                    edge_brightness = 1.5
                else:
                    edge_brightness = 1.0 - progress * 0.3
                
                final_color = tuple(min(255, int(c * edge_brightness)) for c in base_color)
                add_voxel(volume, cx + face_x, cy - y, cz + face_z, final_color)

def generate_crystal_core(volume, cx, cy, cz, height, t, crystal_id):
    # Rotating prismatic core
    core_rotation = t * 2.0 + crystal_id * 1.5
    
    for y in range(int(height * 0.8)):
        progress = y / height
        core_radius = 2 * (1 - progress * 0.5)
        
        # Rainbow core that shifts over time
        hue = (core_rotation * 50 + y * 10) % 360
        core_color = hsv_to_rgb(hue, 0.8, 1.0)
        
        for dx in range(-int(core_radius), int(core_radius) + 1):
            for dz in range(-int(core_radius), int(core_radius) + 1):
                if dx*dx + dz*dz <= core_radius*core_radius:
                    add_voxel(volume, cx + dx, cy - y, cz + dz, core_color)

def generate_particles(volume, cx, cy, cz, t, crystal_id):
    # Swirling particles around the base
    for i in range(PARTICLE_COUNT // CRYSTAL_COUNT):
        particle_t = t * 1.5 + i * 0.5 + crystal_id * 2.0
        
        # Circular motion around crystal base
        radius = 8 + 3 * np.sin(particle_t * 0.8)
        height_offset = abs(np.sin(particle_t * 1.2)) * 15
        
        px = cx + int(radius * np.cos(particle_t))
        py = cy + int(height_offset)
        pz = cz + int(radius * np.sin(particle_t))
        
        # Particle color based on position and time
        hue = (particle_t * 100 + i * 30) % 360
        particle_color = hsv_to_rgb(hue, 0.6, 0.9)
        
        add_voxel(volume, px, py, pz, particle_color)
        
        # Add some particle trails
        for trail in range(3):
            trail_x = px - int(trail * np.cos(particle_t))
            trail_z = pz - int(trail * np.sin(particle_t))
            faded_color = tuple(int(c * (0.8 - trail * 0.2)) for c in particle_color)
            add_voxel(volume, trail_x, py, trail_z, faded_color)

def generate_light_rays(volume, cx, cy, cz, height, t, crystal_id):
    # Light beams shooting upward from crystal tips
    pulse = 0.5 + 0.5 * np.sin(t * 3.0 + crystal_id * 1.2)
    ray_intensity = int(255 * pulse)
    
    ray_color = (ray_intensity, ray_intensity // 2, ray_intensity)
    
    # Multiple light rays
    for ray in range(3):
        ray_angle = (ray / 3.0) * 2 * np.pi + t * 0.5
        
        for y in range(height, height + 15):
            spread = (y - height) * 0.3
            
            ray_x = cx + int(spread * np.cos(ray_angle))
            ray_z = cz + int(spread * np.sin(ray_angle))
            
            # Fade the ray as it goes up
            fade = 1.0 - (y - height) / 15.0
            faded_color = tuple(int(c * fade) for c in ray_color)
            
            add_voxel(volume, ray_x, cy - y, ray_z, faded_color)

def generate_crystal_cluster(volume, cx, cy, cz, t):
    crystal_colors = [
        (100, 200, 255),  # Ice blue
        (255, 100, 200),  # Pink
        (150, 255, 150),  # Green
        (255, 255, 100),  # Yellow
        (200, 150, 255),  # Purple
        (255, 180, 100),  # Orange
    ]
    
    for i in range(CRYSTAL_COUNT):
        # Position crystals in a circle
        angle = (i / CRYSTAL_COUNT) * 2 * np.pi
        radius = 25 + 5 * np.sin(i * 0.7 + t * 0.3)
        
        crystal_x = cx + int(radius * np.cos(angle))
        crystal_z = cz + int(radius * np.sin(angle))
        crystal_y = cy + int(3 * np.sin(t * 0.8 + i * 0.5))
        
        height = CRYSTAL_HEIGHT + int(5 * np.sin(t * 0.6 + i * 0.4))
        color = crystal_colors[i % len(crystal_colors)]
        
        generate_crystal_body(volume, crystal_x, crystal_y, crystal_z, color, height, t, i)
        generate_crystal_core(volume, crystal_x, crystal_y, crystal_z, height, t, i)
        generate_particles(volume, crystal_x, crystal_y, crystal_z, t, i)
        generate_light_rays(volume, crystal_x, crystal_y, crystal_z, height, t, i)

def generate_scene(volume, t):
    generate_crystal_cluster(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 crystals"):
    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 CRYSTAL_COUNT to create more crystal formations.
Modify crystal_colors to experiment with different color schemes.
Adjust CRYSTAL_HEIGHT and CRYSTAL_BASE_RADIUS for different crystal sizes.
Add more particle effects by increasing PARTICLE_COUNT.
Create pulsing crystals by modifying the growth calculation in generate_crystal_body().

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