Emberwild/scripts/world/props.gd

extends Node3D
## Scenery: forests, rocks, cliff outcrops, bushes, logs, grass and flowers.
##
## All placement is seeded, so a server and its clients would agree on where
## every tree is (docs/ARCHITECTURE.md §4). Rendering uses MultiMesh batches
## bucketed into CELL x CELL world cells: a few hundred draw batches instead of
## thousands of nodes, and off-screen cells get frustum-culled.
##
## Trees, logs and larger rocks in or near the walkable valley get simple
## collision. Grass is streamed in tiles around the player because it's too
## dense to place over the whole map at once.

const ProcMesh = preload("res://scripts/world/proc_mesh.gd")
const ResourceNodeScript = preload("res://scripts/world/resource_node.gd")
const PickupScript = preload("res://scripts/world/pickup.gd")

const CELL := 48.0
const GRASS_TILE := 12.0
const FLOWER_COLORS := [
	Color(0.96, 0.95, 0.90), Color(0.98, 0.84, 0.25), Color(0.62, 0.42, 0.86),
	Color(0.45, 0.60, 0.95), Color(0.93, 0.45, 0.55),
]

@export var world_seed: int = 1337
@export var tree_spacing: float = 3.6
@export var forest_density: float = 1.0
@export var grass_spacing: float = 0.42
@export var grass_view_distance: float = 55.0
@export var grass_tiles_per_update: int = 6

var terrain: Node3D
var _player: Node3D
var _spawn := Vector3.ZERO
var _forest_noise := FastNoiseLite.new()
var _meadow_noise := FastNoiseLite.new()
var _colliders: StaticBody3D
var _resources: Node3D   ## harvestable trees/boulders (each its own body)

## Stable ids for saving. Placement is deterministic for a given seed, so
## creation order gives the same id to the same tree on every load.
var resource_nodes: Dictionary = {}   ## uid -> resource node
var pickups: Dictionary = {}          ## uid -> pickup

var _bark_mat: StandardMaterial3D
var _leaf_mat: ShaderMaterial
var _rock_mat: ShaderMaterial
var _grass_mat: ShaderMaterial

var _grass_root: Node3D
var _grass_tiles: Dictionary = {}   # Vector2i -> Node3D (or null for empty tiles)
var _grass_mesh: ArrayMesh
var _flower_mesh: ArrayMesh
var _grass_timer := 0.0

func place_on(t: Node3D, player: Node3D, spawn: Vector3) -> void:
	terrain = t
	_player = player
	_spawn = spawn
	world_seed = terrain.noise_seed   # one seed drives terrain and scenery
	_forest_noise.seed = world_seed + 11
	_forest_noise.noise_type = FastNoiseLite.TYPE_SIMPLEX_SMOOTH
	_forest_noise.frequency = 0.011
	_forest_noise.fractal_octaves = 3
	_meadow_noise.seed = world_seed + 23
	_meadow_noise.noise_type = FastNoiseLite.TYPE_SIMPLEX_SMOOTH
	_meadow_noise.frequency = 0.03
	_meadow_noise.fractal_octaves = 2

	_colliders = StaticBody3D.new()
	_colliders.name = "PropColliders"
	add_child(_colliders)
	_resources = Node3D.new()
	_resources.name = "Resources"
	add_child(_resources)

	_make_materials()
	_scatter_trees()
	_scatter_rocks()
	_scatter_bushes()
	_place_logs()
	_scatter_pickups()

	_grass_root = Node3D.new()
	_grass_root.name = "Grass"
	add_child(_grass_root)
	_grass_mesh = ProcMesh.grass_clump(world_seed + 5)
	_grass_mesh.surface_set_material(0, _grass_mat)
	_flower_mesh = ProcMesh.flower(world_seed + 6)
	var stem := StandardMaterial3D.new()
	stem.vertex_color_use_as_albedo = true
	stem.vertex_color_is_srgb = true
	stem.cull_mode = BaseMaterial3D.CULL_DISABLED
	var head := stem.duplicate() as StandardMaterial3D
	head.roughness = 0.7
	_flower_mesh.surface_set_material(0, stem)
	_flower_mesh.surface_set_material(1, head)
	_update_grass(100000)   # everything in range, before the first frame

func _process(delta: float) -> void:
	if _player == null:
		return
	_grass_timer -= delta
	if _grass_timer > 0.0:
		return
	_grass_timer = 0.2
	_update_grass(grass_tiles_per_update)

# --- materials --------------------------------------------------------------

func _make_materials() -> void:
	var noise_tex: Texture2D = terrain.noise_tex
	_bark_mat = StandardMaterial3D.new()
	_bark_mat.vertex_color_use_as_albedo = true
	_bark_mat.vertex_color_is_srgb = true
	_bark_mat.roughness = 1.0

	_leaf_mat = ShaderMaterial.new()
	_leaf_mat.shader = preload("res://shaders/foliage.gdshader")
	_leaf_mat.set_shader_parameter("noise_tex", noise_tex)

	_rock_mat = ShaderMaterial.new()
	_rock_mat.shader = preload("res://shaders/rock.gdshader")
	_rock_mat.set_shader_parameter("noise_tex", noise_tex)
	_rock_mat.set_shader_parameter("snow_height", terrain.snow_height)

	_grass_mat = ShaderMaterial.new()
	_grass_mat.shader = preload("res://shaders/grass.gdshader")
	_grass_mat.set_shader_parameter("noise_tex", noise_tex)
	_grass_mat.set_shader_parameter("grass_lush", terrain.grass_lush)
	_grass_mat.set_shader_parameter("grass_dry", terrain.grass_dry)

func _apply_materials(v: Dictionary) -> Dictionary:
	var mesh: ArrayMesh = v.mesh
	var surfaces: Array = v.surfaces
	for i in range(surfaces.size()):
		mesh.surface_set_material(i, _bark_mat if surfaces[i] == "bark" else _leaf_mat)
	return v

# --- helpers ----------------------------------------------------------------

## Jittered grid covering the whole chunk.
func _jittered(spacing: float, rng: RandomNumberGenerator) -> PackedVector2Array:
	var pts := PackedVector2Array()
	var half: float = terrain.size * 0.5 - 2.0
	var z := -half
	while z < half:
		var x := -half
		while x < half:
			pts.append(Vector2(x + rng.randf() * spacing, z + rng.randf() * spacing))
			x += spacing
		z += spacing
	return pts

func _forest(x: float, z: float) -> float:
	return smoothstep(-0.15, 0.35, _forest_noise.get_noise_2d(x, z))

## Adds a transform to its cell batch. Returns [key, index] so a resource node
## can find its own instance once the batch exists.
func _group(groups: Dictionary, x: float, z: float, vi: int, xf: Transform3D) -> Array:
	var key := Vector3i(floori(x / CELL), floori(z / CELL), vi)
	if not groups.has(key):
		groups[key] = []
	groups[key].append(xf)
	return [key, groups[key].size() - 1]

## Builds the batches. Returns key -> MultiMeshInstance3D.
func _flush(groups: Dictionary, meshes: Array, shadows: bool, label: String) -> Dictionary:
	var root := Node3D.new()
	root.name = label
	add_child(root)
	var out := {}
	for key: Vector3i in groups:
		var mmi := _mm_instance(meshes[key.z], groups[key], [], shadows)
		root.add_child(mmi)
		out[key] = mmi
	return out

## Hands each pending resource node its batch instance.
func _bind_nodes(pending: Array, batches: Dictionary) -> void:
	for p in pending:
		var node = p[0]
		node.mmi = batches[p[1]]
		node.index = p[2]

func _resource_node(kind: String, xf: Transform3D) -> StaticBody3D:
	var node: StaticBody3D = ResourceNodeScript.new()
	node.uid = "%s%d" % [kind[0], resource_nodes.size()]
	resource_nodes[node.uid] = node
	node.kind = kind
	node.base_xf = xf
	node.stump_material = _bark_mat
	node.rng.seed = hash(xf.origin)
	node.add_to_group("harvestable")
	if kind == "tree":
		node.tool_kind = "axe"
		node.max_hp = 5.0
		node.drops_final = {"wood": [4, 6], "stick": [1, 3]}
		node.chip_color = Color(0.62, 0.46, 0.28)
	else:
		node.tool_kind = "pickaxe"
		node.max_hp = 6.0
		node.drops_per_hit = {"stone": 1}
		node.drops_final = {"stone": [3, 5], "flint": [1, 2]}
		node.chip_color = Color(0.55, 0.54, 0.52)
	node.hp = node.max_hp
	_resources.add_child(node)
	node.global_position = xf.origin
	return node

func _mm_instance(mesh: Mesh, xforms: Array, colors: Array, shadows: bool) -> MultiMeshInstance3D:
	var mm := MultiMesh.new()
	mm.transform_format = MultiMesh.TRANSFORM_3D
	mm.use_colors = not colors.is_empty()   # must be set before instance_count
	mm.mesh = mesh
	mm.instance_count = xforms.size()
	for i in range(xforms.size()):
		mm.set_instance_transform(i, xforms[i])
		if not colors.is_empty():
			mm.set_instance_color(i, colors[i])
	var mmi := MultiMeshInstance3D.new()
	mmi.multimesh = mm
	mmi.cast_shadow = GeometryInstance3D.SHADOW_CASTING_SETTING_ON if shadows else GeometryInstance3D.SHADOW_CASTING_SETTING_OFF
	return mmi

## Basis that tips `UP` part-way toward the ground normal, then yaws and scales.
func _ground_basis(normal: Vector3, follow: float, yaw: float, s: float) -> Basis:
	var up := Vector3.UP.lerp(normal, follow).normalized()
	var b := Basis(Vector3.UP, yaw)
	var axis := Vector3.UP.cross(up)
	if axis.length() > 0.0001:
		b = Basis(axis.normalized(), Vector3.UP.angle_to(up)) * b
	return b * Basis.from_scale(Vector3.ONE * s)

func _add_shape(shape: Shape3D, xf: Transform3D) -> void:
	var cs := CollisionShape3D.new()
	cs.shape = shape
	cs.transform = xf
	_colliders.add_child(cs)

# --- trees ------------------------------------------------------------------

func _scatter_trees() -> void:
	var variants: Array = []
	var conifers: Array[int] = []
	var broad: Array[int] = []
	var birches: Array[int] = []
	for i in range(3):
		conifers.append(variants.size()); variants.append(_apply_materials(ProcMesh.conifer(world_seed + 100 + i, false)))
	for i in range(2):
		conifers.append(variants.size()); variants.append(_apply_materials(ProcMesh.conifer(world_seed + 110 + i, true)))
	for i in range(3):
		var col: Color = ProcMesh.LEAF_GOLD if i == 2 else ProcMesh.LEAF_GREEN
		broad.append(variants.size()); variants.append(_apply_materials(ProcMesh.broadleaf(world_seed + 120 + i, col)))
	for i in range(2):
		birches.append(variants.size()); variants.append(_apply_materials(ProcMesh.birch(world_seed + 130 + i)))
	var dead := variants.size()
	variants.append(_apply_materials(ProcMesh.dead_tree(world_seed + 140)))

	var rng := RandomNumberGenerator.new()
	rng.seed = world_seed + 1
	var groups := {}
	var pending: Array = []
	for p in _jittered(tree_spacing, rng):
		# Draw every random number up front so the sequence never depends on
		# which branch below is taken (stable layout when rules are tweaked).
		var roll := rng.randf()
		var pick := rng.randf()
		var yaw := rng.randf() * TAU
		var s := rng.randf_range(0.75, 1.3)
		var h: float = terrain.sample_height(p.x, p.y)
		if roll > _tree_chance(p.x, p.y, h) * forest_density:
			continue
		var vi: int
		var conifer_p := lerpf(0.4, 0.97, smoothstep(2.0, 24.0, h))
		if pick < 0.025:
			vi = dead
		elif pick < conifer_p:
			vi = conifers[int(pick * 9973.0) % conifers.size()]
		elif (pick - conifer_p) / (1.0 - conifer_p) < 0.6:
			vi = broad[int(pick * 7919.0) % broad.size()]
		else:
			vi = birches[int(pick * 7919.0) % birches.size()]
		var xf := Transform3D(Basis(Vector3.UP, yaw) * Basis.from_scale(Vector3.ONE * s), Vector3(p.x, h - 0.1, p.y))
		var slot := _group(groups, p.x, p.y, vi, xf)
		if terrain.inside_boundary(p.x, p.y, -4.0):
			# Reachable trees are harvestable: their own body + trunk capsule.
			var v: Dictionary = variants[vi]
			var cap := CapsuleShape3D.new()
			cap.radius = v.trunk_r * s
			cap.height = maxf(v.trunk_h * s, cap.radius * 2.0 + 0.1)
			var node := _resource_node("tree", xf)
			if vi == dead:
				node.drops_final = {"wood": [2, 3], "stick": [2, 4]}
				node.max_hp = 3.0
				node.hp = 3.0
			var cs := CollisionShape3D.new()
			cs.shape = cap
			cs.position = Vector3(0, cap.height * 0.5 + 0.1, 0)
			node.add_child(cs)
			pending.append([node, slot[0], slot[1]])
	var meshes := variants.map(func(v): return v.mesh)
	_bind_nodes(pending, _flush(groups, meshes, true, "Trees"))

## Open grassy strip along the sea-cliff edge: no trees, bushes or boulders, so
## the view out to sea is clear and you can walk right up to the edge.
func _on_clifftop(x: float, z: float) -> bool:
	return terrain.sea_weight(x, z) > 0.5 and not terrain.inside_boundary(x, z, 10.0) \
		and terrain.inside_boundary(x, z, -8.0)

func _tree_chance(x: float, z: float, h: float) -> float:
	if h < terrain.water_level + 0.8:
		return 0.0
	if Vector2(x - _spawn.x, z - _spawn.z).length() < 9.0 or _on_clifftop(x, z):
		return 0.0
	var n: Vector3 = terrain.sample_normal(x, z)
	var slope := 1.0 - n.y
	if slope > 0.5:
		return 0.0
	var c := lerpf(0.035, 0.8, _forest(x, z))
	c *= 1.0 - smoothstep(0.25, 0.5, slope)
	c *= 1.0 - smoothstep(terrain.snow_height - 12.0, terrain.snow_height - 2.0, h)
	return c

# --- rocks ------------------------------------------------------------------

func _scatter_rocks() -> void:
	var meshes: Array = []
	var hulls: Array = []
	for i in range(7):
		var m := ProcMesh.rock(world_seed + 300 + i, i >= 5)
		m.surface_set_material(0, _rock_mat)
		meshes.append(m)
		hulls.append((m.create_convex_shape(true, true) as ConvexPolygonShape3D).points)
	var rng := RandomNumberGenerator.new()
	rng.seed = world_seed + 2
	var groups := {}
	var pending: Array = []

	# Small stones: everywhere, more on slopes and in the shallows.
	for p in _jittered(6.0, rng):
		var roll := rng.randf(); var vi := rng.randi_range(0, 4); var yaw := rng.randf() * TAU
		var s := rng.randf_range(0.2, 0.75)
		var h: float = terrain.sample_height(p.x, p.y)
		var n: Vector3 = terrain.sample_normal(p.x, p.y)
		var chance := 0.1 + (1.0 - n.y) * 0.8
		if h < terrain.water_level - 2.0 or roll > chance:
			continue
		_place_rock(groups, meshes, hulls, p, h, n, vi, yaw, s, 0.6, 0.25)

	# Boulders: sparse, a little more common in forests.
	for p in _jittered(14.0, rng):
		var roll := rng.randf(); var vi := rng.randi_range(0, 4); var yaw := rng.randf() * TAU
		var s := rng.randf_range(1.2, 3.0)
		var h: float = terrain.sample_height(p.x, p.y)
		var n: Vector3 = terrain.sample_normal(p.x, p.y)
		if h < terrain.water_level - 0.5 or Vector2(p.x - _spawn.x, p.y - _spawn.z).length() < 8.0 or _on_clifftop(p.x, p.y):
			continue
		if roll > 0.07 + _forest(p.x, p.y) * 0.08:
			continue
		_place_rock(groups, meshes, hulls, p, h, n, vi, yaw, s, 0.5, 0.3, pending)

	# Cliff outcrops: big slabs breaking up the steep mountain faces.
	for p in _jittered(8.0, rng):
		var roll := rng.randf(); var vi := rng.randi_range(0, 6); var yaw := rng.randf() * TAU
		var s := rng.randf_range(3.0, 8.0)
		var n: Vector3 = terrain.sample_normal(p.x, p.y)
		if 1.0 - n.y < 0.32 or roll > 0.22:
			continue
		var h: float = terrain.sample_height(p.x, p.y)
		_place_rock(groups, meshes, hulls, p, h, n, vi, yaw, s, 0.9, 0.6)

	# Sea stacks: tall pillars standing off the cliff (no collision, unreachable).
	var placed := 0
	var tries := 0
	while placed < 9 and tries < 200:
		tries += 1
		var ang: float = terrain.sea_angle_deg + rng.randf_range(-1.0, 1.0) * (terrain.sea_half_width_deg + 8.0)
		var p: Vector2 = terrain.coast_point(ang, rng.randf_range(10.0, 48.0))
		var vi := rng.randi_range(5, 6)
		var yaw := rng.randf() * TAU
		var s := rng.randf_range(3.5, 7.0)
		var h: float = terrain.sample_height(p.x, p.y)
		if h > terrain.sea_level - 3.0:
			continue
		var b := Basis(Vector3.UP, yaw) * Basis.from_scale(Vector3(s, s * rng.randf_range(1.8, 2.6), s))
		_group(groups, p.x, p.y, vi, Transform3D(b, Vector3(p.x, h - 1.0, p.y)))
		placed += 1

	_bind_nodes(pending, _flush(groups, meshes, true, "Rocks"))

## Places one rock. Passing `pending` makes it a mineable boulder (if it's
## inside the walkable area); otherwise it just gets plain collision.
func _place_rock(groups: Dictionary, meshes: Array, hulls: Array, p: Vector2, h: float, n: Vector3,
		vi: int, yaw: float, s: float, follow: float, sink: float, pending = null) -> void:
	var b := _ground_basis(n, follow, yaw, s)
	var pos := Vector3(p.x, h - sink * s, p.y)
	var slot := _group(groups, p.x, p.y, vi, Transform3D(b, pos))
	if s >= 0.55 and terrain.inside_boundary(p.x, p.y, -6.0):
		var pts := PackedVector3Array()
		for q: Vector3 in hulls[vi]:
			pts.append(q * s)
		var shape := ConvexPolygonShape3D.new()
		shape.points = pts
		if pending != null and terrain.inside_boundary(p.x, p.y, 0.0):
			var node := _resource_node("rock", Transform3D(b, pos))
			var cs := CollisionShape3D.new()
			cs.shape = shape
			cs.basis = b.orthonormalized()
			node.add_child(cs)
			pending.append([node, slot[0], slot[1]])
		else:
			_add_shape(shape, Transform3D(b.orthonormalized(), pos))

# --- bushes, logs, stumps ---------------------------------------------------

func _scatter_bushes() -> void:
	var meshes: Array = []
	for i in range(3):
		meshes.append(_apply_materials(ProcMesh.bush(world_seed + 200 + i)).mesh)
	var rng := RandomNumberGenerator.new()
	rng.seed = world_seed + 3
	var groups := {}
	for p in _jittered(4.5, rng):
		var roll := rng.randf(); var vi := rng.randi_range(0, 2); var yaw := rng.randf() * TAU
		var s := rng.randf_range(0.7, 1.5)
		var h: float = terrain.sample_height(p.x, p.y)
		var n: Vector3 = terrain.sample_normal(p.x, p.y)
		if h < terrain.water_level + 0.5 or n.y < 0.75 or h > terrain.snow_height - 8.0:
			continue
		if Vector2(p.x - _spawn.x, p.y - _spawn.z).length() < 4.0 or _on_clifftop(p.x, p.y):
			continue
		var f := _forest(p.x, p.y)
		var edge := 1.0 - absf(f - 0.5) * 2.0   # forest edges get the most undergrowth
		if roll > 0.05 + 0.4 * edge:
			continue
		_group(groups, p.x, p.y, vi, Transform3D(_ground_basis(n, 0.5, yaw, s), Vector3(p.x, h - 0.1, p.y)))
	_flush(groups, meshes, true, "Bushes")

func _place_logs() -> void:
	var root := Node3D.new()
	root.name = "Logs"
	add_child(root)
	var rng := RandomNumberGenerator.new()
	rng.seed = world_seed + 4
	var logs := 0
	var stumps := 0
	var tries := 0
	while (logs < 22 or stumps < 30) and tries < 4000:
		tries += 1
		var x := rng.randf_range(-terrain.play_radius, terrain.play_radius)
		var z := rng.randf_range(-terrain.play_radius, terrain.play_radius)
		var yaw := rng.randf() * TAU
		var make_log := rng.randf() < 0.45
		if not terrain.inside_boundary(x, z, 6.0) or _forest(x, z) < 0.35:
			continue
		var h: float = terrain.sample_height(x, z)
		var n: Vector3 = terrain.sample_normal(x, z)
		if h < terrain.water_level + 0.6 or n.y < 0.97 or Vector2(x - _spawn.x, z - _spawn.z).length() < 8.0:
			continue
		var mi := MeshInstance3D.new()
		var shape: Shape3D
		var xf: Transform3D
		if make_log and logs < 22:
			var length := rng.randf_range(3.0, 5.0)
			var r := rng.randf_range(0.22, 0.34)
			mi.mesh = ProcMesh.log_mesh(world_seed + 400 + logs, length, r)
			xf = Transform3D(_ground_basis(n, 1.0, yaw, 1.0), Vector3(x, h + r * 0.75, z))
			var box := BoxShape3D.new()
			box.size = Vector3(length, r * 1.8, r * 1.8)
			shape = box
			logs += 1
		elif not make_log and stumps < 30:
			var sh := rng.randf_range(0.35, 0.7)
			var r := rng.randf_range(0.25, 0.4)
			mi.mesh = ProcMesh.stump_mesh(world_seed + 500 + stumps, sh, r)
			xf = Transform3D(Basis(Vector3.UP, yaw), Vector3(x, h, z))
			var cyl := CylinderShape3D.new()
			cyl.radius = r * 1.1
			cyl.height = sh + 0.3
			shape = cyl
			stumps += 1
		else:
			mi.free()
			continue
		mi.material_override = _bark_mat
		mi.transform = xf
		root.add_child(mi)
		var col_xf := xf
		if shape is CylinderShape3D:
			col_xf.origin.y += (shape as CylinderShape3D).height * 0.5 - 0.3
		_add_shape(shape, col_xf)

# --- ground pickups ---------------------------------------------------------

## Sticks under trees, stones everywhere, flint near water and on rocky ground.
## Enough for the first tools without hunting around for long.
func _scatter_pickups() -> void:
	var root := Node3D.new()
	root.name = "Pickups"
	add_child(root)
	var rng := RandomNumberGenerator.new()
	rng.seed = world_seed + 6
	var want := {"stick": 260, "stone": 170, "flint": 80}
	var radius: Dictionary = {"stick": 0.35, "stone": 0.25, "flint": 0.25}
	for id: String in want:
		var mesh := ItemDB.mesh_for(id)
		var placed := 0
		var tries := 0
		while placed < want[id] and tries < 20000:
			tries += 1
			var x := rng.randf_range(-terrain.play_radius, terrain.play_radius)
			var z := rng.randf_range(-terrain.play_radius, terrain.play_radius)
			var yaw := rng.randf() * TAU
			var keep := rng.randf()
			if not terrain.inside_boundary(x, z, 3.0):
				continue
			var h: float = terrain.sample_height(x, z)
			var n: Vector3 = terrain.sample_normal(x, z)
			if h < terrain.water_level + 0.3 or n.y < 0.8:
				continue
			var chance := 1.0
			match id:
				"stick":
					chance = 0.08 + _forest(x, z) * 0.9
				"flint":
					var shore := 1.0 - smoothstep(terrain.water_level + 0.5, terrain.water_level + 4.0, h)
					chance = 0.06 + shore * 0.9 + (1.0 - n.y) * 2.0
			# A few right by the spawn so the first craft is quick.
			if Vector2(x - _spawn.x, z - _spawn.z).length() < 18.0:
				chance += 0.5
			if keep > chance:
				continue
			var pk: Area3D = PickupScript.new()
			pk.setup(id, mesh, ItemDB.item_material(), radius[id])
			pk.uid = "p%d" % pickups.size()
			pickups[pk.uid] = pk
			root.add_child(pk)
			pk.global_transform = Transform3D(_ground_basis(n, 1.0, yaw, 1.0), Vector3(x, h - 0.02, z))
			placed += 1

# --- grass streaming --------------------------------------------------------

func _update_grass(budget: int) -> void:
	var p := _player.global_position
	var reach := grass_view_distance + GRASS_TILE
	var c := Vector2i(floori(p.x / GRASS_TILE), floori(p.z / GRASS_TILE))
	var tr := int(ceil(reach / GRASS_TILE))
	var wanted := {}
	var todo: Array = []
	for dz in range(-tr, tr + 1):
		for dx in range(-tr, tr + 1):
			var k := c + Vector2i(dx, dz)
			var d := Vector2((k.x + 0.5) * GRASS_TILE, (k.y + 0.5) * GRASS_TILE).distance_to(Vector2(p.x, p.z))
			if d > reach:
				continue
			wanted[k] = true
			if not _grass_tiles.has(k):
				todo.append([d, k])
	todo.sort_custom(func(a, b): return a[0] < b[0])
	for i in range(mini(budget, todo.size())):
		var k: Vector2i = todo[i][1]
		_grass_tiles[k] = _make_grass_tile(k)
	for k: Vector2i in _grass_tiles.keys():
		if wanted.has(k):
			continue
		var d := Vector2((k.x + 0.5) * GRASS_TILE, (k.y + 0.5) * GRASS_TILE).distance_to(Vector2(p.x, p.z))
		if d > reach + GRASS_TILE * 1.5:
			var node = _grass_tiles[k]
			if node != null and is_instance_valid(node):
				node.queue_free()
			_grass_tiles.erase(k)

func _make_grass_tile(k: Vector2i) -> Node3D:
	var rng := RandomNumberGenerator.new()
	rng.seed = hash(k) ^ world_seed
	var ox := k.x * GRASS_TILE
	var oz := k.y * GRASS_TILE
	var centre := Vector3(ox + GRASS_TILE * 0.5, 0.0, oz + GRASS_TILE * 0.5)
	var grass_xf: Array = []
	var flower_xf: Array = []
	var flower_col: Array = []
	var steps := int(GRASS_TILE / grass_spacing)
	for iz in range(steps):
		for ix in range(steps):
			var x := ox + (ix + rng.randf()) * grass_spacing
			var z := oz + (iz + rng.randf()) * grass_spacing
			var keep := rng.randf(); var yaw := rng.randf() * TAU
			var s := rng.randf_range(0.75, 1.25); var fl := rng.randf()
			if not terrain.in_bounds(x, z):
				continue
			var h: float = terrain.sample_height(x, z)
			if h < terrain.water_level + 0.25 or h > terrain.snow_height - 6.0:
				continue
			var n: Vector3 = terrain.sample_normal(x, z)
			if n.y < 0.72:
				continue
			var meadow := _meadow_noise.get_noise_2d(x, z)
			var dens := smoothstep(-0.45, 0.1, meadow) * (1.0 - smoothstep(0.85, 0.72, n.y) * 0.7)
			if keep > dens:
				continue
			var tall := lerpf(0.7, 1.35, smoothstep(-0.1, 0.4, meadow))
			var b := Basis(Vector3.UP, yaw) * Basis.from_scale(Vector3(s, s * tall, s))
			grass_xf.append(Transform3D(b, Vector3(x - centre.x, h - 0.03, z - centre.z)))
			if fl < 0.02 * smoothstep(0.0, 0.4, meadow):
				var ci := int(absf(_forest_noise.get_noise_2d(x * 3.0, z * 3.0)) * 10.0) % FLOWER_COLORS.size()
				flower_xf.append(Transform3D(Basis(Vector3.UP, yaw) * Basis.from_scale(Vector3.ONE * s), Vector3(x - centre.x, h, z - centre.z)))
				flower_col.append(FLOWER_COLORS[ci])
	if grass_xf.is_empty():
		return null
	var node := Node3D.new()
	node.position = centre
	var g := _mm_instance(_grass_mesh, grass_xf, [], false)
	_fade(g, grass_view_distance)
	node.add_child(g)
	if not flower_xf.is_empty():
		var f := _mm_instance(_flower_mesh, flower_xf, flower_col, false)
		_fade(f, grass_view_distance * 0.7)
		node.add_child(f)
	_grass_root.add_child(node)
	return node

func _fade(gi: GeometryInstance3D, dist: float) -> void:
	gi.visibility_range_end = dist
	gi.visibility_range_end_margin = 10.0
	gi.visibility_range_fade_mode = GeometryInstance3D.VISIBILITY_RANGE_FADE_SELF