Initial commit

Scenes/Scripts/moon_imposter.gd

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+extends Node3D
+## Swap only when the real Moon is about to leave the far plane.
+## At handover the disc matches the real angular size. It shrinks with distance.
+## A late boost only kicks in when the disc would become a speck (Earth).
+
+@export var real_moon_path: NodePath = ^".."
+@export var surface_high_path: NodePath = ^"../SurfaceHigh"
+@export var impostor_mesh_path: NodePath = ^"ImposterSphere"
+@export var switch_distance: float = 850000.0
+@export var visual_distance: float = 280000.0
+@export var real_radius: float = 173700.0
+@export var far_boost_start: float = 2500000.0
+@export var far_boost_end: float = 20000000.0
+@export var far_boost: float = 5.0
+
+var _real_moon: Node3D
+var _surface_high: Node3D
+var _surface_low: Node3D
+var _mesh: MeshInstance3D
+var _base_radius: float = 0.5
+
+
+func _ready() -> void:
+	_real_moon = get_node_or_null(real_moon_path) as Node3D
+	_surface_high = get_node_or_null(surface_high_path) as Node3D
+	if _surface_high == null and _real_moon:
+		_surface_high = _real_moon.get_node_or_null("SurfaceHigh") as Node3D
+	if _real_moon:
+		_surface_low = _real_moon.get_node_or_null("SurfaceLow") as Node3D
+	_mesh = get_node_or_null(impostor_mesh_path) as MeshInstance3D
+	if _mesh == null:
+		_mesh = find_child("ImposterSphere", true, false) as MeshInstance3D
+	if _mesh:
+		_mesh.top_level = true
+		_mesh.visible = false
+		_mesh.cast_shadow = GeometryInstance3D.SHADOW_CASTING_SETTING_OFF
+		if _mesh.mesh is SphereMesh:
+			var sm := _mesh.mesh as SphereMesh
+			_base_radius = maxf(sm.radius, 0.5)
+			sm.radial_segments = maxi(sm.radial_segments, 32)
+			sm.rings = maxi(sm.rings, 16)
+		var mat := _mesh.get_active_material(0)
+		if mat == null:
+			mat = _mesh.material_override
+		if mat is StandardMaterial3D:
+			var copy := (mat as StandardMaterial3D).duplicate() as StandardMaterial3D
+			copy.shading_mode = BaseMaterial3D.SHADING_MODE_UNSHADED
+			_mesh.material_override = copy
+	print("MoonImposter ready switch=", switch_distance, " mesh=", _mesh)
+	set_process(true)
+
+
+func _hide_real(hide: bool) -> void:
+	if _surface_high:
+		_surface_high.visible = not hide
+	if _surface_low:
+		_surface_low.visible = not hide
+
+
+func _process(_delta: float) -> void:
+	if _real_moon == null or _mesh == null:
+		return
+	var viewer: Node3D = FloatingOrigin.focus
+	if viewer == null or not is_instance_valid(viewer):
+		_mesh.visible = false
+		return
+	if _real_moon.has_meta("hide_crust") and bool(_real_moon.get_meta("hide_crust")):
+		_mesh.visible = false
+		_hide_real(true)
+		return
+	var to_moon: Vector3 = _real_moon.global_position - viewer.global_position
+	var dist: float = to_moon.length()
+	if dist < switch_distance:
+		_mesh.visible = false
+		_hide_real(false)
+		return
+	_hide_real(true)
+	var dir: Vector3 = to_moon / maxf(dist, 1.0)
+	_mesh.global_position = viewer.global_position + dir * visual_distance
+	var exact: float = real_radius * (visual_distance / dist)
+	var t: float = 0.0
+	if dist > far_boost_start:
+		t = clampf((dist - far_boost_start) / maxf(far_boost_end - far_boost_start, 1.0), 0.0, 1.0)
+	var visual_radius: float = exact * lerpf(1.0, far_boost, t)
+	visual_radius = clampf(visual_radius, 200.0, visual_distance * 0.85)
+	_mesh.scale = Vector3.ONE * (visual_radius / _base_radius)
+	_mesh.visible = true