Voxel-based worlds have fascinated me since I first played Minecraft. There's something deeply satisfying about building destructible, modifiable environments where every cube matters. When I started exploring voxel systems in Godot, I discovered it's both more accessible and more complex than I initially thought.
Why Voxels?
Voxels (volumetric pixels) give you incredible flexibility for procedural generation and player interaction. Unlike traditional mesh-based geometry, voxels let you:
- Dynamically modify terrain in real-time
- Generate infinite or semi-infinite worlds
- Implement destruction systems naturally
- Create mining/building mechanics effortlessly
The tradeoff? Performance. Rendering millions of cubes naively will bring any system to its knees. The key is clever optimization.
The Basic Data Structure
At its core, a voxel world is just a 3D array. In Godot, I use a chunk-based system where the world is divided into 16x16x16 sections:
class_name VoxelChunk
extends MeshInstance3D
const CHUNK_SIZE = 16
var voxel_data: Array = []
func _init():
# Initialize 3D array
voxel_data.resize(CHUNK_SIZE)
for x in CHUNK_SIZE:
voxel_data[x] = []
voxel_data[x].resize(CHUNK_SIZE)
for y in CHUNK_SIZE:
voxel_data[x][y] = []
voxel_data[x][y].resize(CHUNK_SIZE)
func get_voxel(x: int, y: int, z: int) -> int:
if x < 0 or x >= CHUNK_SIZE or y < 0 or y >= CHUNK_SIZE or z < 0 or z >= CHUNK_SIZE:
return 0
return voxel_data[x][y][z]
func set_voxel(x: int, y: int, z: int, type: int):
if x < 0 or x >= CHUNK_SIZE or y < 0 or y >= CHUNK_SIZE or z < 0 or z >= CHUNK_SIZE:
return
voxel_data[x][y][z] = type
rebuild_mesh()Greedy Meshing: The Performance Multiplier
The naive approach of creating a cube mesh for every voxel is a performance nightmare. Instead, we use "greedy meshing" to combine adjacent faces into larger quads. This can reduce vertex counts by 80-90%.
Here's the core idea: for each axis (X, Y, Z), we scan through slices and merge adjacent faces of the same type:
func generate_mesh() -> ArrayMesh:
var surface_tool = SurfaceTool.new()
surface_tool.begin(Mesh.PRIMITIVE_TRIANGLES)
# Generate faces for each direction
for axis in 3: # X, Y, Z
for direction in [-1, 1]: # Negative and positive
generate_faces(surface_tool, axis, direction)
surface_tool.generate_normals()
return surface_tool.commit()
func generate_faces(st: SurfaceTool, axis: int, dir: int):
var u = (axis + 1) % 3
var v = (axis + 2) % 3
var x = [0, 0, 0]
var q = [0, 0, 0]
q[axis] = 1
# Scan through each slice
for x[axis] in range(CHUNK_SIZE):
var mask = []
mask.resize(CHUNK_SIZE * CHUNK_SIZE)
# Generate mask for this slice
for x[v] in range(CHUNK_SIZE):
for x[u] in range(CHUNK_SIZE):
var current = get_voxel(x[0], x[1], x[2])
var neighbor_pos = x.duplicate()
neighbor_pos[axis] += dir
var neighbor = get_voxel_safe(neighbor_pos)
# Create face if there's a transition
if current != 0 and neighbor == 0:
mask[x[u] + x[v] * CHUNK_SIZE] = current
else:
mask[x[u] + x[v] * CHUNK_SIZE] = 0
# Generate quads from mask
greedy_mesh_slice(st, mask, axis, dir, x[axis])Chunk Management
For larger worlds, you need a chunk management system that loads/unloads chunks based on player position. I use a simple distance-based system:
var active_chunks: Dictionary = {}
var render_distance: int = 8
func update_chunks(player_pos: Vector3):
var player_chunk = world_to_chunk(player_pos)
var chunks_to_load = []
var chunks_to_unload = []
# Find chunks that should be loaded
for x in range(-render_distance, render_distance + 1):
for z in range(-render_distance, render_distance + 1):
var chunk_pos = player_chunk + Vector3i(x, 0, z)
if chunk_pos not in active_chunks:
chunks_to_load.append(chunk_pos)
# Find chunks that should be unloaded
for chunk_pos in active_chunks:
var distance = (chunk_pos - player_chunk).length()
if distance > render_distance + 2:
chunks_to_unload.append(chunk_pos)
# Load/unload chunks
for pos in chunks_to_load:
load_chunk(pos)
for pos in chunks_to_unload:
unload_chunk(pos)Godot 4.x Improvements
Moving from Godot 3.x to 4.x brought significant improvements for voxel systems:
- Better threading: WorkerThreadPool makes chunk generation async much cleaner
- Improved ArrayMesh: Faster mesh creation and modification
- Better culling: Godot 4's rendering is more efficient with many objects
- Compute shaders: Can offload mesh generation to GPU (advanced)
Procedural Generation
Most voxel worlds use noise functions for terrain generation. Godot's FastNoiseLite is perfect for this:
var noise = FastNoiseLite.new()
func _ready():
noise.noise_type = FastNoiseLite.TYPE_PERLIN
noise.frequency = 0.02
noise.fractal_octaves = 4
func generate_chunk_data(chunk_pos: Vector3i):
for x in CHUNK_SIZE:
for z in CHUNK_SIZE:
var world_x = chunk_pos.x * CHUNK_SIZE + x
var world_z = chunk_pos.z * CHUNK_SIZE + z
# Generate height using noise
var height = noise.get_noise_2d(world_x, world_z) * 20 + 40
# Fill voxels up to height
for y in CHUNK_SIZE:
var world_y = chunk_pos.y * CHUNK_SIZE + y
if world_y < height:
var voxel_type = get_voxel_type(world_y, height)
set_voxel(x, y, z, voxel_type)Lessons Learned
After building several voxel systems, here are my key takeaways:
- Start simple: Get basic chunk rendering working before optimizing
- Profile everything: Your intuition about performance bottlenecks is probably wrong
- Use threads wisely: Mesh generation is perfect for threading, but be careful with Godot's scene tree
- Cache aggressively: Regenerating meshes is expensive, avoid it when possible
- LOD is your friend: Use lower resolution meshes for distant chunks
Next Steps
Once you have basic voxel rendering working, there are endless directions to explore:
- Cave systems using 3D noise
- Dynamic lighting per-voxel
- Smooth voxel terrain (marching cubes)
- Physics integration for destruction
- Multiplayer synchronization
Voxel systems are a rabbit hole of optimization and creativity. Whether you're building a Minecraft clone or incorporating voxel destruction into a hybrid game, understanding these fundamentals will serve you well.