Improve tree gathering and rain occlusion

world/environment/precipitation_occlusion.gd

@@ -0,0 +1,56 @@
+class_name PrecipitationOcclusion
+extends RefCounted
+
+## A secondary visual layer used only when building the local rain height field.
+## Canopy meshes remain on layer 1 for ordinary cameras.
+const RENDER_LAYER_NUMBER: int = 20
+const RENDER_LAYER_MASK: int = 1 << (RENDER_LAYER_NUMBER - 1)
+const CANOPY_MATERIAL_NAMES: Array[String] = [
+	"leaf",
+	"leaf_light",
+	"leaf_mid",
+	"leaf_dark",
+	"pine",
+	"tree",
+]
+
+
+static func mark_canopy_meshes(root_node: Node) -> int:
+	if root_node == null:
+		return 0
+	var marked_count: int = 0
+	var mesh_instance := root_node as MeshInstance3D
+	if mesh_instance != null and _has_canopy_material(mesh_instance):
+		mesh_instance.layers |= RENDER_LAYER_MASK
+		marked_count += 1
+	for child: Node in root_node.get_children():
+		marked_count += mark_canopy_meshes(child)
+	return marked_count
+
+
+## Generated tree definitions are already explicit terrain metadata, so every
+## mesh in their visual scene can safely participate. This also supports older
+## combined tree meshes whose imported material name does not identify leaves.
+static func mark_tree_meshes(root_node: Node) -> int:
+	if root_node == null:
+		return 0
+	var marked_count: int = 0
+	var mesh_instance := root_node as MeshInstance3D
+	if mesh_instance != null:
+		mesh_instance.layers |= RENDER_LAYER_MASK
+		marked_count += 1
+	for child: Node in root_node.get_children():
+		marked_count += mark_tree_meshes(child)
+	return marked_count
+
+
+static func _has_canopy_material(mesh_instance: MeshInstance3D) -> bool:
+	if mesh_instance == null or mesh_instance.mesh == null:
+		return false
+	for surface_index: int in mesh_instance.mesh.get_surface_count():
+		var material := mesh_instance.mesh.surface_get_material(surface_index)
+		if material == null:
+			continue
+		if material.resource_name.to_lower() in CANOPY_MATERIAL_NAMES:
+			return true
+	return false

world/generation/generated_world_region.gd

@@ -12,6 +12,9 @@ const PlayerStorageInteractionType = preload(
 const MeshSurfaceAnchorSamplerType = preload(
 	"res://world/generation/mesh_surface_anchor_sampler.gd"
 )
+const PrecipitationOcclusionType = preload(
+	"res://world/environment/precipitation_occlusion.gd"
+)
 const WATER_BODY_SCENE: PackedScene = preload("res://world/water_body.tscn")
 const SALT_WATER_MATERIAL: Material = preload(
 	"res://world/materials/stylized_water.tres"
@@ -292,9 +295,21 @@ func _on_generation_completed(summary: Dictionary) -> void:
 	_place_spawn_amenities(spawn_position)
 	_configure_fresh_water(records)
 	_configure_diggable_area()
+	# Imported prop instances may finish applying their scene state while the
+	# generated world is assembled. Mark the final decoration tree once every
+	# prop and material variant is in place so rain canopy occlusion persists.
+	_mark_precipitation_occluders()
 	world_generated.emit(_current_seed, summary)
 
 
+func _mark_precipitation_occluders() -> void:
+	for prop: Node in _decorations.get_children():
+		var prop_group := prop.get_meta(&"terrain_prop_group", &"") as StringName
+		if prop_group not in [&"grass_tree", &"sand_tree"]:
+			continue
+		PrecipitationOcclusionType.mark_tree_meshes(prop)
+
+
 func _assign_biomes(
 	records: Array[Dictionary],
 	summary: Dictionary,

world/generation/props/definitions/prop_pine.tres

@@ -17,4 +17,3 @@ minimum_visual_scale = 0.65
 maximum_visual_scale = 1.2
 collision_radius = 0.5
 collision_height = 4.0
-gatherable_surface_material_names = PackedStringArray("wood")

world/generation/props/definitions/prop_pine_large.tres

@@ -17,4 +17,3 @@ minimum_visual_scale = 0.75
 maximum_visual_scale = 1.2
 collision_radius = 0.65
 collision_height = 9.5
-gatherable_surface_material_names = PackedStringArray("wood")

world/regions/starter_island_region.gd

@@ -11,6 +11,9 @@ const PlayerStorageInteractionType = preload(
 const FOLIAGE_WIND_SHADER: Shader = preload(
 	"res://world/materials/foliage_wind.gdshader"
 )
+const PrecipitationOcclusionType = preload(
+	"res://world/environment/precipitation_occlusion.gd"
+)
 const FOLIAGE_MATERIAL_NAMES: Array[StringName] = [
 	&"leaf",
 	&"leaf_light",
@@ -60,6 +63,9 @@ var _foliage_wind_enabled: bool = false
 func _ready() -> void:
 	if rebuild_terrain_collision_on_ready or not has_terrain_collision():
 		_build_terrain_collision()
+	PrecipitationOcclusionType.mark_canopy_meshes(
+		get_node_or_null(terrain_visual_root_path)
+	)
 	_set_foliage_wind_enabled(true)
 	if Engine.is_editor_hint():
 		update_configuration_warnings()

world/world_time_visual_controller.gd

@@ -17,6 +17,8 @@ const LIGHT_RAIN_FIXED_FPS: int = 8
 const RAIN_VELOCITY_MIN: float = 16.0
 const RAIN_VELOCITY_MAX: float = 20.0
 const RAIN_DROP_SIZE := Vector3(0.014, 0.34, 0.014)
+const RAIN_COLLISION_BASE_SIZE: float = 0.08
+const RAIN_COLLISION_SIZE := Vector3(28.0, 24.0, 28.0)
 const FOG_DAYLIGHT_SCENE_BRIGHTNESS: float = 0.42
 const FOG_DAYLIGHT_FOG_LIGHT_BRIGHTNESS: float = 0.42
 const FOG_DAYLIGHT_WATER_BRIGHTNESS: float = 0.42
@@ -37,6 +39,9 @@ const FRESH_WATER_MATERIAL: ShaderMaterial = preload(
 const LocalStormCloudLayerType = preload(
 	"res://world/environment/local_storm_cloud_layer.gd"
 )
+const PrecipitationOcclusionType = preload(
+	"res://world/environment/precipitation_occlusion.gd"
+)
 
 const DAY_SKY_TOP := Color(0.204, 0.498, 0.643)
 const DAY_SKY_HORIZON := Color(0.663, 0.843, 0.847)
@@ -88,6 +93,7 @@ var _rain_camera_provider: Callable
 var _environment: Environment
 var _sky_material: ShaderMaterial
 var _rain: GPUParticles3D
+var _rain_collision: GPUParticlesCollisionHeightField3D
 var _storm_clouds: LocalStormCloudLayer
 var _elapsed: float = 0.0
 var _weather_from: WorldWeatherService.Weather = (
@@ -211,6 +217,7 @@ func _prepare_rain() -> void:
 		LIGHT_RAIN_FIXED_FPS if _light_performance_profile else 30
 	)
 	_rain.local_coords = false
+	_rain.collision_base_size = RAIN_COLLISION_BASE_SIZE
 	_rain.visibility_aabb = RAIN_VISIBILITY_AABB
 	var process_material := ParticleProcessMaterial.new()
 	process_material.emission_shape = (
@@ -222,6 +229,9 @@ func _prepare_rain() -> void:
 	process_material.initial_velocity_min = RAIN_VELOCITY_MIN
 	process_material.initial_velocity_max = RAIN_VELOCITY_MAX
 	process_material.gravity = Vector3(0.0, -2.0, 0.0)
+	process_material.collision_mode = (
+		ParticleProcessMaterial.COLLISION_HIDE_ON_CONTACT
+	)
 	_rain.process_material = process_material
 	var drop_mesh := BoxMesh.new()
 	drop_mesh.size = RAIN_DROP_SIZE
@@ -232,9 +242,30 @@ func _prepare_rain() -> void:
 	drop_mesh.material = drop_material
 	_rain.draw_pass_1 = drop_mesh
 	add_child(_rain)
+	_prepare_rain_collision()
 	_update_rain_position()
 
 
+func _prepare_rain_collision() -> void:
+	_rain_collision = GPUParticlesCollisionHeightField3D.new()
+	_rain_collision.name = "LocalRainCanopyCollision"
+	_rain_collision.size = RAIN_COLLISION_SIZE
+	_rain_collision.resolution = (
+		GPUParticlesCollisionHeightField3D.RESOLUTION_256
+	)
+	_rain_collision.update_mode = (
+		GPUParticlesCollisionHeightField3D.UPDATE_MODE_WHEN_MOVED
+	)
+	_rain_collision.follow_camera_enabled = true
+	_rain_collision.heightfield_mask = (
+		PrecipitationOcclusionType.RENDER_LAYER_MASK
+	)
+	# Local rain remains on its normal layer; unrelated particle systems do not
+	# need to query this weather-specific collision field.
+	_rain_collision.cull_mask = 1
+	add_child(_rain_collision)
+
+
 func _prepare_storm_clouds() -> void:
 	_storm_clouds = LocalStormCloudLayerType.new()
 	_storm_clouds.name = "LocalStormClouds"