Godot Genre Sandbox

# skills/genre-sandbox/scripts/cellular_automata_liquid.gd
extends Node

## Cellular Automata Liquid (Expert Pattern)
## Logic for falling sand/water simulation in a grid.
## NOT a Node that enters the scene tree per cell, but a logic handler.

class_name CellularAutomataLiquid

const TYPE_EMPTY = 0
const TYPE_SAND = 1
const TYPE_WATER = 2
const TYPE_WALL = 3

static func simulate_grid(grid: Dictionary, width: int, height: int, dirty_cells: Array) -> void:
    # Sort dirty cells bottom-up, to process floor first. 
    # Actually for falling sand, we want to process BOTTOM UP so a falling stack moves together?
    # No, iterating bottom-up allows a grain to fall into the empty space created by the grain below it moving?
    # Actually, standard is: Iterate bottom-up.
    
    # Simple sort for example (Optimization: Use a proper dirty rect or active list)
    dirty_cells.sort_custom(func(a,b): return a.y > b.y) # Higher Y is lower on screen usually, check coord system
    # Assuming Y+ is Down. 
    
    var processed = {} # Prevent double moves
    
    for pos in dirty_cells:
        if processed.has(pos): continue
        
        var type = grid.get(pos, TYPE_EMPTY)
        if type == TYPE_SAND:
            _update_sand(grid, pos, processed)
        elif type == TYPE_WATER:
            _update_water(grid, pos, processed)

static func _update_sand(grid: Dictionary, pos: Vector2i, processed: Dictionary) -> void:
    var down = pos + Vector2i(0, 1)
    if not grid.has(down): # Empty
        _move(grid, pos, down, processed)
    else:
        var down_left = pos + Vector2i(-1, 1)
        var down_right = pos + Vector2i(1, 1)
        # Random disperse
        var moves = [down_left, down_right]
        moves.shuffle()
        for m in moves:
            if not grid.has(m):
                _move(grid, pos, m, processed)
                return

static func _update_water(grid: Dictionary, pos: Vector2i, processed: Dictionary) -> void:
    var down = pos + Vector2i(0, 1)
    if not grid.has(down):
        _move(grid, pos, down, processed)
        return
        
    # Flow sideways
    var left = pos + Vector2i(-1, 0)
    var right = pos + Vector2i(1, 0)
    var moves = [left, right]
    moves.shuffle()
    for m in moves:
        if not grid.has(m):
             _move(grid, pos, m, processed)
             return

static func _move(grid: Dictionary, from: Vector2i, to: Vector2i, processed: Dictionary) -> void:
    var type = grid[from]
    grid.erase(from)
    grid[to] = type
    processed[to] = true
    # Note: This simple dict approach is not performant for 100k cells.
    # Use PackedByteArray and flat indexing for real implementations.

## EXPERT USAGE:
## Call from _physics_process on the active chunk data.

extends Node3D
class_name DynamicPlacementValidator

## Expert Grid Placement (Godot 4.6).
## Low-level physics intersection check for obstruction validation.

@export var grid_size: float = 2.0
@export var ghost_shape: Shape3D

func get_grid_pos(raw_pos: Vector3) -> Vector3:
	return raw_pos.snapped(Vector3.ONE * grid_size)

func is_spot_clear(pos: Vector3) -> bool:
	var space = get_world_3d().direct_space_state
	var query = PhysicsShapeQueryParameters3D.new()
	query.shape = ghost_shape
	query.transform = Transform3D(Basis(), pos)
	
	# Expert Pattern: Query physics server directly for instant results
	var results = space.intersect_shape(query, 1)
	return results.is_empty()

## [SKILL NOTICE]: Use 'intersect_shape()' on the physics space state 
## for instant placement validation. Avoid using Area3D signals for this.

# sandbox_patterns.gd
extends Node

# 1. Background Async Chunk Loading
# EXPERT NOTE: Use ResourceLoader for non-blocking asset loading during exploration.
func load_chunk_async(path: String) -> void:
    ResourceLoader.load_threaded_request(path)

func get_loaded_chunk(path: String) -> PackedScene:
    if ResourceLoader.load_threaded_get_status(path) == ResourceLoader.THREAD_LOAD_LOADED:
        return ResourceLoader.load_threaded_get(path)
    return null

# 2. Multithreaded Terrain Generation
# EXPERT NOTE: Dispatches array math to available worker threads to prevent stalls.
func generate_terrain_mesh() -> void:
    WorkerThreadPool.add_task(_compute_noise_arrays, true, "TerrainGen")

func _compute_noise_arrays() -> void:
    # Heavy noise/array computation here
    pass

# 3. Thread-Safe Data Mutation (Mutex)
# EXPERT NOTE: Synchronize access to shared chunk data across threads.
var _chunk_mutex := Mutex.new()
func safely_update_chunk_data(callback: Callable) -> void:
    _chunk_mutex.lock()
    callback.call()
    _chunk_mutex.unlock()

# 4. Modifying 3D GridMaps (Block Placement)
# EXPERT NOTE: High-performance cell manipulation for voxel-style interactions.
func place_block(grid: GridMap, world_pos: Vector3, block_id: int) -> void:
    var map_coords := grid.local_to_map(world_pos)
    grid.set_cell_item(map_coords, block_id)

# 5. Saving Voxel Data to Binary
# EXPERT NOTE: .res is highly optimized for large arrays compared to text formats.
func save_binary_world_data(resource: Resource, path: String) -> void:
    ResourceSaver.save(resource, path)

# 6. Procedural Geometry (SurfaceTool)
# EXPERT NOTE: Building custom meshes dynamically for terrain/buildings.
func build_custom_mesh() -> Mesh:
    var st := SurfaceTool.new()
    st.begin(Mesh.PRIMITIVE_TRIANGLES)
    st.set_normal(Vector3.UP)
    st.add_vertex(Vector3(-1, 0, -1))
    st.add_vertex(Vector3(1, 0, -1))
    st.add_vertex(Vector3(0, 0, 1))
    return st.commit()

# 7. Serializing Chunk Entities
# EXPERT NOTE: Recursively save child node states into a dictionary.
func serialize_chunk(nodes: Array[Node]) -> Dictionary:
    var data := {}
    for node in nodes:
        if node.has_method(&"save"):
            data[node.name] = node.call(&"save")
    return data

# 8. Fast Physics Picking for Interaction
# EXPERT NOTE: Optimized raycasting for voxel targeting.
func get_aimed_block(cam: Camera3D, screen_pos: Vector2) -> Dictionary:
    var origin := cam.project_ray_origin(screen_pos)
    var direction := cam.project_ray_normal(screen_pos)
    var query := PhysicsRayQueryParameters3D.create(origin, origin + direction * 10)
    return cam.get_world_3d().direct_space_state.intersect_ray(query)

# 9. VoxelGI Runtime Allocation
# EXPERT NOTE: Assign procedural data into the Global Illumination server natively.
func setup_global_illumination(gi_rid: RID, aabb: AABB, data: PackedByteArray) -> void:
    RenderingServer.voxel_gi_allocate_data(gi_rid, Transform3D.IDENTITY, aabb, Vector3i(64,64,64), data, data, data, PackedInt32Array())

# 10. Large World Origin Shifting
# EXPERT NOTE: Periodically reset the world origin to prevent floating-point jitter.
func shift_world_origin(new_origin: Vector3) -> void:
    for child in get_tree().root.get_children():
        if child is Node3D:
            child.global_position -= new_origin

extends Node
class_name SandboxWorldSerializer

## Expert Sandbox Serialization (Godot 4.6).
## Serializes all player-placed 'Persist' nodes to JSON.

const SAVE_PATH = "user://sandbox_world.json"

func save_world() -> void:
	var data = []
	for node in get_tree().get_nodes_in_group("Persist"):
		if node.scene_file_path.is_empty(): continue
		
		var node_data = {
			"res": node.scene_file_path,
			"pos": var_to_str(node.global_position),
			"rot": var_to_str(node.global_rotation)
		}
		data.append(node_data)
	
	var file = FileAccess.open(SAVE_PATH, FileAccess.WRITE)
	file.store_string(JSON.stringify(data))

func load_world() -> void:
	if not FileAccess.file_exists(SAVE_PATH): return
	
	var file = FileAccess.open(SAVE_PATH, FileAccess.READ)
	var data = JSON.parse_string(file.get_as_text())
	
	for entry in data:
		var scene = load(entry.res) as PackedScene
		var inst = scene.instantiate() as Node3D
		get_tree().current_scene.add_child(inst)
		inst.global_position = str_to_var(entry.pos)
		inst.global_rotation = str_to_var(entry.rot)

## [SKILL NOTICE]: Use 'scene_file_path' and 'str_to_var()' to cleanly 
## serialize complex 3D world states into lightweight JSON files.

# skills/genre-sandbox/code/voxel_chunk_manager.gd
extends Node3D

## Voxel Chunk Manager Expert Pattern
## Manages chunked rendering using MultiMeshInstance3D for optimization.

@export var chunk_size: Vector3i = Vector3i(16, 16, 16)
@export var voxel_mesh: Mesh

var _chunks: Dictionary = {} # Dictionary of Vector3i -> MultiMeshInstance3D

func set_voxel(world_pos: Vector3i, type: int) -> void:
    var chunk_coord = Vector3i(
        floor(float(world_pos.x) / chunk_size.x),
        floor(float(world_pos.y) / chunk_size.y),
        floor(float(world_pos.z) / chunk_size.z)
    )
    
    var local_pos = world_pos - (chunk_coord * chunk_size)
    _update_chunk(chunk_coord, local_pos, type)

func _update_chunk(coord: Vector3i, local_pos: Vector3i, type: int) -> void:
    if not _chunks.has(coord):
        _create_chunk(coord)
        
    var mm = _chunks[coord]
    # In an expert implementation, we would manage a typed buffer here.
    # For the pattern, we show the transformation logic.
    var index = _get_index(local_pos)
    var transform = Transform3D(Basis(), Vector3(local_pos))
    
    if type > 0:
        mm.multimesh.set_instance_transform(index, transform)
        # mm.multimesh.set_instance_custom_data(index, Color(type, 0, 0))
    else:
        # Hide the voxel by moving it out of view or scaling to 0
        mm.multimesh.set_instance_transform(index, Transform3D(Basis().scaled(Vector3.ZERO), Vector3.ZERO))

func _create_chunk(coord: Vector3i) -> void:
    var mm = MultiMeshInstance3D.new()
    mm.multimesh = MultiMesh.new()
    mm.multimesh.transform_format = MultiMesh.TRANSFORM_3D
    mm.multimesh.use_custom_data = true
    mm.multimesh.instance_count = chunk_size.x * chunk_size.y * chunk_size.z
    mm.multimesh.mesh = voxel_mesh
    
    add_child(mm)
    mm.global_position = Vector3(coord * chunk_size)
    _chunks[coord] = mm

func _get_index(pos: Vector3i) -> int:
    return pos.x + (pos.y * chunk_size.x) + (pos.z * chunk_size.x * chunk_size.y)

## EXPERT NOTE:
## For performance, NEVER update MultiMesh instance transforms every frame.
## Only update when the voxel data changes.
## For 'genre-sandbox' games like Minecraft, use a custom MESH GENERATOR 
## (SurfaceTool) to create an optimized "Greedy Meshed" chunk instead of 
## individual meshes to reduce draw calls from thousands to one.

extends MeshInstance3D
class_name VoxelChunkMesher

## Expert Voxel Meshing (Godot 4.6).
## Uses SurfaceTool with background threading (WorkerThreadPool).

const CHUNK_SIZE = 16
var _voxels: PackedByteArray # 16x16x16 = 4096 bytes

func regenerate_mesh() -> void:
	# Expert Pattern: Offload generation to save frame budget
	WorkerThreadPool.add_task(_build_surface)

func _build_surface() -> void:
	var st = SurfaceTool.new()
	st.begin(Mesh.PRIMITIVE_TRIANGLES)
	
	for x in CHUNK_SIZE:
		for y in CHUNK_SIZE:
			for z in CHUNK_SIZE:
				if _get_voxel(x, y, z) > 0:
					_add_visible_faces(st, x, y, z)
	
	st.index()
	st.generate_normals()
	var final_mesh = st.commit()
	
	# Thread-safe assignment
	call_deferred("set_mesh", final_mesh)

func _add_visible_faces(st: SurfaceTool, x: int, y: int, z: int) -> void:
	# Face Culling: Only add faces if the neighbor is transparent/air
	if _get_voxel(x, y + 1, z) == 0:
		_add_face(st, Vector3(x, y + 1, z), Vector3.UP)

func _get_voxel(x, y, z) -> 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 _voxels[x + (y * CHUNK_SIZE) + (z * CHUNK_SIZE * CHUNK_SIZE)]

## [SKILL NOTICE]: Use 'WorkerThreadPool' to generate voxel meshes. 
## This prevents frame drops when players modify large chunks of the world.

# skills/genre-sandbox/scripts/voxel_world.gd
extends Node3D

## Voxel World Manager (Expert Pattern)
## Handles chunk management for voxel worlds. 
## Barebones structure for Dictionary-based sparse storage.

class_name VoxelWorld

@export var chunk_size: int = 16
@export var render_distance: int = 4
@export var player: Node3D

var chunks: Dictionary = {} # Vector3i -> ChunkNode

func _process(delta: float) -> void:
    if not player: return
    
    var player_chunk = _world_to_chunk(player.global_position)
    _update_chunks(player_chunk)

func _update_chunks(center: Vector3i) -> void:
    # 1. Identify needs
    var needed = []
    for x in range(-render_distance, render_distance + 1):
        for y in range(-2, 3): # Height limit usually smaller
            for z in range(-render_distance, render_distance + 1):
                needed.append(center + Vector3i(x, y, z))
                
    # 2. Unload
    var to_remove = []
    for key in chunks:
        if not key in needed:
            to_remove.append(key)
            
    for key in to_remove:
        chunks[key].queue_free()
        chunks.erase(key)
        
    # 3. Load (Simplistic main thread for example, should be Threaded)
    for key in needed:
        if not chunks.has(key):
            _create_chunk(key)

func _create_chunk(coord: Vector3i) -> void:
    var chunk = Node3D.new() # Placeholder for MeshInstance
    chunk.name = "Chunk_%s_%s_%s" % [coord.x, coord.y, coord.z]
    chunks[coord] = chunk
    add_child(chunk)
    # Trigger generation thread here

func _world_to_chunk(pos: Vector3) -> Vector3i:
    return Vector3i(floor(pos.x / chunk_size), floor(pos.y / chunk_size), floor(pos.z / chunk_size))

## EXPERT USAGE:
## extend this script to integrate actual mesh generation.