Brachistochrone/kestrel_driver.gd

extends Node3D
## Kestrel EC-01 plume driver. Godot 4.7.
## Attach to the Kestrel child. Leave escape_capsule.gd on EscapeCapsule.
## Nose +Y, starboard +X, dorsal +Z. The four abort motors are the drive plume.
##
## This script does not move the hull. escape_capsule.gd owns velocity.
## listen_keys is off so walking the player does not light jets or shove the craft.
## Capsule sets abort_burn, att_pitch/yaw/roll, rcs_direction, hatches, cabin_dim.

@export var listen_keys := false
@export_range(0.0, 1.0) var gear_deploy := 1.0
@export_range(0.0, 1.0) var hatch_crew_open := 0.0
@export_range(0.0, 1.0) var hatch_ladder_deploy := 0.0
@export_range(0.0, 1.0) var hatch_dock_open := 0.0
@export_range(0.0, 1.0) var instruments_demo := 0.4
@export var cabin_lights := true
@export var cabin_dim := false
@export_enum("Off", "Nose", "Tail", "Starboard", "Port", "Dorsal", "Ventral") var rcs_direction := 0
@export var att_pitch := 0.0
@export var att_yaw := 0.0
@export var att_roll := 0.0
@export var abort_burn := false
## Tick this in the inspector (or Remote tab while running) to self-test every jet.
@export var debug_fire := false

const _RIBBON := "shader_type spatial;
render_mode blend_add, unshaded, cull_disabled, depth_draw_never, fog_disabled;
uniform vec4 root_color : source_color = vec4(1.0, 1.0, 1.0, 0.95);
uniform vec4 mid_color : source_color = vec4(0.47, 0.71, 1.0, 0.35);
uniform vec4 tip_color : source_color = vec4(0.16, 0.31, 1.0, 0.0);
uniform float opacity : hint_range(0.0, 2.0, 0.001) = 0.0;
void fragment() {
	float v = UV.y;
	float edge = abs(UV.x - 0.5) * 2.0;
	float side = 1.0 - smoothstep(0.36, 1.0, edge);
	vec3 col = mix(root_color.rgb, mid_color.rgb, smoothstep(0.0, 0.45, v));
	col = mix(col, tip_color.rgb, smoothstep(0.35, 1.0, v));
	float a = mix(root_color.a, mid_color.a, smoothstep(0.05, 0.45, v));
	a = mix(a, tip_color.a, smoothstep(0.45, 1.0, v));
	ALBEDO = col;
	ALPHA = clamp(a * side * opacity, 0.0, 1.0);
}"

var _player: AnimationPlayer
var _shader: Shader
var _rcs: Array[Node3D] = []
var _aborts: Array[Dictionary] = []
var _abort_hold := 0.0
var _time := 0.0
var _prev := {}
var _clip_cache := {}
var _warm_frames := 12
var _cabin_ready := false
var _applied_dim := false
var _applied_lights := true
var _cabin_lights_n: Array[Light3D] = []
var _cabin_rest: Array[Dictionary] = []
var _cabin_mats: Array[Dictionary] = []

const _DIRS: Array[Vector3] = [
	Vector3.ZERO, Vector3(0, 1, 0), Vector3(0, -1, 0),
	Vector3(1, 0, 0), Vector3(-1, 0, 0), Vector3(0, 0, 1), Vector3(0, 0, -1),
]


func _ready() -> void:
	_shader = Shader.new()
	_shader.code = _RIBBON
	_player = get_node_or_null("AnimationPlayer") as AnimationPlayer
	if _player == null:
		_player = find_child("AnimationPlayer", true, false) as AnimationPlayer
	_arm()
	_collect_cabin()
	_apply_clips()
	print("Kestrel driver ready: rcs=", _rcs.size(), " abort=", _aborts.size(),
		" cabin_lights=", _cabin_lights_n.size(), " strips=", _cabin_mats.size(),
		" anim_player=", _player != null)
	if _rcs.is_empty():
		push_warning("Kestrel driver: no Vfx_RCS_* nodes found under " + str(get_path()))
	if _aborts.is_empty():
		push_warning("Kestrel driver: no Vfx_Abort_* nodes found under " + str(get_path()))
	if _player == null:
		push_warning("Kestrel driver: no AnimationPlayer found (gear/hatches will not move)")


func _physics_process(delta: float) -> void:
	_time += delta
	if listen_keys:
		_read_keys()
	if debug_fire:
		abort_burn = true
		rcs_direction = 1 + int(_time) % 6
	_apply_clips()
	if _warm_frames > 0:
		_warm_frames -= 1
	# FIX: the capsule sets cabin_dim as a plain variable, so nothing re-applied it.
	if cabin_dim != _applied_dim or cabin_lights != _applied_lights:
		_apply_cabin()
	_burn(_wish(), delta)


func _read_keys() -> void:
	if _pressed(KEY_G):
		gear_deploy = 0.0 if gear_deploy > 0.5 else 1.0
	if _pressed(KEY_C):
		hatch_crew_open = 0.0 if hatch_crew_open > 0.5 else 1.0
	if _pressed(KEY_L):
		hatch_ladder_deploy = 0.0 if hatch_ladder_deploy > 0.5 else 1.0
	if _pressed(KEY_H):
		hatch_dock_open = 0.0 if hatch_dock_open > 0.5 else 1.0
	if _pressed(KEY_I):
		instruments_demo = 0.15 if instruments_demo > 0.5 else 1.0
	if _pressed(KEY_K):
		cabin_lights = not cabin_lights
	abort_burn = Input.is_physical_key_pressed(KEY_SPACE)


func _pressed(key: Key) -> bool:
	var down := Input.is_physical_key_pressed(key)
	var was: bool = _prev.get(key, false)
	_prev[key] = down
	return down and not was


func _wish() -> Vector3:
	var local := _DIRS[clampi(rcs_direction, 0, _DIRS.size() - 1)]
	if listen_keys:
		var pad := Vector3.ZERO
		if Input.is_physical_key_pressed(KEY_W):
			pad.y += 1.0
		if Input.is_physical_key_pressed(KEY_S):
			pad.y -= 1.0
		if Input.is_physical_key_pressed(KEY_D):
			pad.x += 1.0
		if Input.is_physical_key_pressed(KEY_A):
			pad.x -= 1.0
		if Input.is_physical_key_pressed(KEY_E):
			pad.z += 1.0
		if Input.is_physical_key_pressed(KEY_Q):
			pad.z -= 1.0
		if pad.length_squared() > 0.0:
			local = pad.normalized()
	if local == Vector3.ZERO:
		return Vector3.ZERO
	return (global_transform.basis * local).normalized()


func _apply_clips() -> void:
	_seek("gear_deploy", gear_deploy)
	_seek("hatch_crew_open", hatch_crew_open)
	_seek("hatch_ladder_deploy", hatch_ladder_deploy)
	_seek("hatch_dock_open", hatch_dock_open)
	_seek("instruments_demo", instruments_demo)


## FIX: only re-seek when the value actually changed. The old version called
## play()+seek()+pause() on five clips every physics frame.
func _clip_name(clip: StringName) -> StringName:
	if _player.has_animation(clip):
		return clip
	for a in _player.get_animation_list():
		if String(a).ends_with("/" + String(clip)):
			return a
	return &""


## Re-seeks only when the value changed, but keeps re-applying for the first few
## frames so the pose sticks after the AnimationPlayer finishes initializing.
func _seek(clip: StringName, t: float) -> void:
	if _player == null:
		return
	var clip_id := _clip_name(clip)
	if clip_id == &"":
		return
	t = clampf(t, 0.0, 1.0)
	if _warm_frames <= 0 and _clip_cache.has(clip) and is_equal_approx(float(_clip_cache[clip]), t):
		return
	_clip_cache[clip] = t
	var clip_len := _player.get_animation(clip_id).length
	_player.play(clip_id)
	_player.seek(t * clip_len, true)
	_player.pause()


func _collect_cabin() -> void:
	_cabin_lights_n.clear()
	_cabin_rest.clear()
	_cabin_mats.clear()
	for n in find_children("*", "Light3D", true, false):
		var nm := String(n.name)
		if nm.begins_with("Nav"):
			continue
		var keep := nm.begins_with("PointLight_") or nm == "CabinFill" or nm == "PanelLight" or nm.begins_with("CabinLamp")
		if not keep:
			var p := n.get_parent()
			while p:
				if String(p.name) == "CabinLights":
					keep = true
					break
				p = p.get_parent()
		if not keep:
			continue
		_cabin_lights_n.append(n)
		_cabin_rest.append({"energy": n.light_energy, "color": n.light_color})
	for n in find_children("*", "MeshInstance3D", true, false):
		if not String(n.name).begins_with("LightStrip"):
			continue
		var mesh := n as MeshInstance3D
		var mat := mesh.get_active_material(0)
		if mat == null or not (mat is StandardMaterial3D):
			continue
		var copy := (mat as StandardMaterial3D).duplicate() as StandardMaterial3D
		mesh.set_surface_override_material(0, copy)
		_cabin_mats.append({"mat": copy, "energy": copy.emission_energy_multiplier, "color": copy.emission, "on": copy.emission_enabled})
	_cabin_ready = true
	_apply_cabin()


func _apply_cabin() -> void:
	if not _cabin_ready:
		return
	_applied_dim = cabin_dim
	_applied_lights = cabin_lights
	var dim := cabin_dim or not cabin_lights
	for i in _cabin_lights_n.size():
		var lamp := _cabin_lights_n[i]
		var rest: Dictionary = _cabin_rest[i]
		lamp.light_color = rest.color
		lamp.light_energy = float(rest.energy) * (0.08 if dim else 1.0)
	for row in _cabin_mats:
		var mat := row.mat as StandardMaterial3D
		mat.emission_enabled = true if dim else bool(row.on)
		mat.emission = row.color
		mat.emission_energy_multiplier = float(row.energy) * (0.05 if dim else 1.0)


func _arm() -> void:
	var i := 0
	for n in find_children("*", "Node3D", true, false):
		var nm := String(n.name)
		if nm.begins_with("Vfx_RCS_"):
			_rcs.append(_spear(n, 1.2, 0.09, Color(0.863, 0.937, 1.0, 0.95), Color(0.41, 0.67, 1.0, 0.35), Color(0.25, 0.45, 0.8, 0.0), 0.82, 2, float(i)))
			i += 1
		elif nm.begins_with("Vfx_Abort_"):
			_aborts.append(_make_abort(n))


func _burn(wish: Vector3, delta: float) -> void:
	var ship := global_transform.basis
	var ship_inv := ship.inverse()
	# FIX: capsule yaws about +Z by +att_yaw (rotate_object_local(FORWARD, -yaw) == +Z, +yaw),
	# so the commanded angular velocity is (pitch, roll, +yaw). The old -att_yaw fired the
	# opposite-side jets for yaw.
	var cmd := Vector3(att_pitch, att_roll, att_yaw)
	var turning := cmd.length() > 0.15
	var origin := global_position
	for ribbon in _rcs:
		var want := 0.0
		var exhaust: Vector3 = (ship_inv * ribbon.global_transform.basis.y).normalized()
		if turning:
			var local_pos: Vector3 = ship_inv * (ribbon.global_position - origin)
			if local_pos.length() < 0.05:
				local_pos = -exhaust
			var torque: Vector3 = local_pos.cross(-exhaust)
			if torque.dot(cmd) > 0.12:
				want = 1.0
		if want < 0.5 and wish != Vector3.ZERO:
			if exhaust.dot(-(ship_inv * wish)) > 0.7:
				want = 1.0
		var burn := float(ribbon.get_meta("burn"))
		burn = _smooth(burn, want, delta, 0.08 if want > burn else 0.14)
		ribbon.set_meta("burn", burn)
		_set_spear(ribbon, burn, _time)
	if abort_burn:
		_abort_hold = minf(1.0, _abort_hold + delta / 0.22)
	else:
		_abort_hold = maxf(0.0, _abort_hold - delta / 0.28)
	var on := _abort_hold > 0.03
	var flick := 0.86 + 0.14 * sin(_time * 41.0)
	var sheath_scale := 0.9 + 0.1 * sin(_time * 19.0)
	for a in _aborts:
		var core := a.core as Node3D
		var sheath := a.sheath as Node3D
		_set_opacity(core, _abort_hold * 0.95 * flick if on else 0.0)
		_set_opacity(sheath, _abort_hold * 0.82 * flick if on else 0.0)
		sheath.scale = Vector3(1, sheath_scale, 1)
		var sparks := a.sparks as GPUParticles3D
		var sheath_sparks := a.sheath_sparks as GPUParticles3D
		sparks.emitting = on
		sheath_sparks.emitting = on
		var proc := sparks.process_material as ParticleProcessMaterial
		var proc2 := sheath_sparks.process_material as ParticleProcessMaterial
		if proc:
			proc.color = Color(1, 1, 1, _abort_hold * 0.55)
		if proc2:
			proc2.color = Color(1, 1, 1, _abort_hold * 0.55)
		var flash := a.flash as MeshInstance3D
		flash.visible = on
		var fmat := flash.material_override as StandardMaterial3D
		if fmat:
			var tint := fmat.albedo_color
			tint.a = _abort_hold * 0.45
			fmat.albedo_color = tint
		flash.scale = Vector3.ONE * (0.06 + _abort_hold * 0.04)
		var light := a.light as SpotLight3D
		light.light_energy = _abort_hold * 8.0 if on else 0.0


## Exhaust direction in the socket's parent space. The model puts each Vfx_ socket's
## translation along its exhaust direction (RCS = +Y, Abort = -Y), so position is the aim.
func _exhaust(socket: Node3D) -> Vector3:
	var dir := socket.position
	if dir.length() < 0.001:
		dir = Vector3.UP
	return (socket.quaternion.inverse() * dir).normalized()


func _basis_y(dir: Vector3) -> Basis:
	var y := dir.normalized()
	if y.length() < 0.001:
		y = Vector3.UP
	var up := Vector3.FORWARD if absf(y.dot(Vector3.UP)) > 0.9 else Vector3.UP
	var x := up.cross(y).normalized()
	var z := x.cross(y).normalized()
	return Basis(x, y, z)


func _ribbon_mat(root: Color, mid: Color, tip: Color) -> ShaderMaterial:
	var mat := ShaderMaterial.new()
	mat.shader = _shader
	mat.set_shader_parameter("root_color", root)
	mat.set_shader_parameter("mid_color", mid)
	mat.set_shader_parameter("tip_color", tip)
	mat.set_shader_parameter("opacity", 0.0)
	return mat


func _sheet(length: float, width: float) -> ArrayMesh:
	var half := width * 0.5
	var st := SurfaceTool.new()
	st.begin(Mesh.PRIMITIVE_TRIANGLES)
	st.set_uv(Vector2(0, 0)); st.add_vertex(Vector3(-half, 0, 0))
	st.set_uv(Vector2(1, 0)); st.add_vertex(Vector3(half, 0, 0))
	st.set_uv(Vector2(1, 1)); st.add_vertex(Vector3(half, length, 0))
	st.set_uv(Vector2(0, 1)); st.add_vertex(Vector3(-half, length, 0))
	st.add_index(0); st.add_index(1); st.add_index(2)
	st.add_index(0); st.add_index(2); st.add_index(3)
	return st.commit()


func _taper(length: float, w0: float, w1: float) -> ArrayMesh:
	var rows := 11
	var st := SurfaceTool.new()
	st.begin(Mesh.PRIMITIVE_TRIANGLES)
	for i in rows:
		var t := float(i) / float(rows - 1)
		var y := t * length
		var w := (w0 + (w1 - w0) * pow(t, 0.7)) * 0.5
		st.set_uv(Vector2(0, t)); st.add_vertex(Vector3(-w, y, 0))
		st.set_uv(Vector2(1, t)); st.add_vertex(Vector3(w, y, 0))
	for i in rows - 1:
		var a := i * 2
		st.add_index(a); st.add_index(a + 1); st.add_index(a + 2)
		st.add_index(a + 1); st.add_index(a + 3); st.add_index(a + 2)
	return st.commit()


func _crossed(socket: Node3D, mesh: ArrayMesh, mat: ShaderMaterial, planes: int, node_name: String, length: float, opacity: float, flick_seed: float) -> Node3D:
	var g := Node3D.new()
	g.name = node_name
	g.set_meta("mat", mat)
	g.set_meta("len", length)
	g.set_meta("opacity", opacity)
	g.set_meta("seed", flick_seed)
	g.set_meta("burn", 0.0)
	for i in planes:
		var m := MeshInstance3D.new()
		m.mesh = mesh
		m.material_override = mat
		m.cast_shadow = GeometryInstance3D.SHADOW_CASTING_SETTING_OFF
		m.extra_cull_margin = 8.0
		m.rotation.y = (float(i) / float(planes)) * PI
		g.add_child(m)
	g.basis = _basis_y(_exhaust(socket))
	g.visible = false
	socket.add_child(g)
	return g


func _spear(socket: Node3D, length: float, width: float, root: Color, mid: Color, tip: Color, opacity: float, planes: int, flick_seed: float) -> Node3D:
	return _crossed(socket, _sheet(length, width), _ribbon_mat(root, mid, tip), planes, "Spear", length, opacity, flick_seed)


func _taper_ribbon(socket: Node3D, length: float, w0: float, w1: float, root: Color, mid: Color, tip: Color, opacity: float, planes: int, node_name: String) -> Node3D:
	return _crossed(socket, _taper(length, w0, w1), _ribbon_mat(root, mid, tip), planes, node_name, length, opacity, 1.0)


func _set_opacity(ribbon: Node3D, opacity: float) -> void:
	var mat := ribbon.get_meta("mat") as ShaderMaterial
	var shown := opacity > 0.02
	ribbon.visible = shown
	mat.set_shader_parameter("opacity", opacity if shown else 0.0)


func _set_spear(ribbon: Node3D, amount: float, time: float) -> void:
	var a := maxf(amount, 0.0)
	if a < 0.02:
		_set_opacity(ribbon, 0.0)
		return
	var flick_seed := float(ribbon.get_meta("seed"))
	var flick := 0.82 + 0.18 * sin(time * 37.0 + flick_seed * 2.1)
	ribbon.scale = Vector3.ONE
	_set_opacity(ribbon, float(ribbon.get_meta("opacity")) * minf(a, 1.0) * flick)


func _smooth(current: float, target: float, delta: float, seconds: float) -> float:
	var k := 1.0 - exp(-delta / maxf(0.05, seconds))
	return current + (target - current) * k


func _soft_disc() -> Texture2D:
	var img := Image.create(64, 64, false, Image.FORMAT_RGBA8)
	for y in 64:
		for x in 64:
			var d := Vector2(x - 31.5, y - 31.5).length() / 32.0
			var t := clampf(d, 0.0, 1.0)
			var s := t * t * (3.0 - 2.0 * t)
			var a := (1.0 - s) * (1.0 - s)
			img.set_pixel(x, y, Color(1, 1, 1, a))
	return ImageTexture.create_from_image(img)


func _disc_mat() -> StandardMaterial3D:
	var draw := StandardMaterial3D.new()
	draw.transparency = BaseMaterial3D.TRANSPARENCY_ALPHA
	draw.blend_mode = BaseMaterial3D.BLEND_MODE_ADD
	draw.shading_mode = BaseMaterial3D.SHADING_MODE_UNSHADED
	draw.billboard_mode = BaseMaterial3D.BILLBOARD_PARTICLES
	draw.vertex_color_use_as_albedo = true
	draw.albedo_texture = _soft_disc()
	draw.albedo_color = Color.WHITE
	draw.cull_mode = BaseMaterial3D.CULL_DISABLED
	draw.depth_draw_mode = BaseMaterial3D.DEPTH_DRAW_DISABLED
	return draw


func _abort_ramp() -> GradientTexture1D:
	var g := Gradient.new()
	g.offsets = PackedFloat32Array([0.0, 0.15, 0.45, 1.0])
	g.colors = PackedColorArray([
		Color(1.0, 0.97, 0.92, 1.0),
		Color(1.0, 0.46, 0.12, 0.9),
		Color(0.55, 0.16, 0.05, 0.45),
		Color(0.25, 0.05, 0.01, 0.0),
	])
	var tex := GradientTexture1D.new()
	tex.gradient = g
	return tex


func _sparks(socket: Node3D, node_name: String, amount: int, life: float, vmin: float, vmax: float, spread_deg: float, size: float, reach: float) -> GPUParticles3D:
	var p := GPUParticles3D.new()
	p.name = node_name
	p.amount = amount
	p.lifetime = life
	p.explosiveness = 0.0
	p.local_coords = true
	p.visibility_aabb = AABB(Vector3(-reach, 0, -reach), Vector3(reach * 2.0, reach * 3.0, reach * 2.0))
	var proc := ParticleProcessMaterial.new()
	proc.direction = Vector3(0, 1, 0)
	proc.spread = spread_deg
	proc.initial_velocity_min = vmin
	proc.initial_velocity_max = vmax
	proc.gravity = Vector3.ZERO
	proc.scale_min = 0.85
	proc.scale_max = 1.15
	proc.color = Color(1, 1, 1, 0.55)
	proc.color_ramp = _abort_ramp()
	p.process_material = proc
	p.material_override = _disc_mat()
	var quad := QuadMesh.new()
	quad.size = Vector2(size, size)
	p.draw_pass_1 = quad
	p.emitting = false
	p.basis = _basis_y(_exhaust(socket))
	socket.add_child(p)
	return p


func _abort_flash(socket: Node3D) -> MeshInstance3D:
	var aim := _basis_y(_exhaust(socket))
	var mat := StandardMaterial3D.new()
	mat.transparency = BaseMaterial3D.TRANSPARENCY_ALPHA
	mat.blend_mode = BaseMaterial3D.BLEND_MODE_ADD
	mat.shading_mode = BaseMaterial3D.SHADING_MODE_UNSHADED
	mat.billboard_mode = BaseMaterial3D.BILLBOARD_ENABLED
	mat.albedo_texture = _soft_disc()
	mat.albedo_color = Color(1.0, 0.945, 0.867, 0.0)
	mat.depth_draw_mode = BaseMaterial3D.DEPTH_DRAW_DISABLED
	var m := MeshInstance3D.new()
	m.name = "AbortFlash"
	var quad := QuadMesh.new()
	quad.size = Vector2(1, 1)
	m.mesh = quad
	m.material_override = mat
	m.cast_shadow = GeometryInstance3D.SHADOW_CASTING_SETTING_OFF
	m.position = aim.y * 0.02
	m.scale = Vector3.ONE * 0.08
	m.visible = false
	socket.add_child(m)
	return m


func _spot(socket: Node3D) -> SpotLight3D:
	var aim := _basis_y(_exhaust(socket))
	var light := SpotLight3D.new()
	light.name = "ExhaustLight"
	light.light_color = Color(1.0, 0.416, 0.157)
	light.light_energy = 0.0
	light.spot_range = 6.5
	light.spot_angle = rad_to_deg(0.5)
	light.spot_attenuation = 1.8
	light.shadow_enabled = false
	light.position = aim.y * 0.08
	var z := -(aim.y)
	var up := aim.x
	var x := up.cross(z).normalized()
	var y := z.cross(x).normalized()
	light.basis = Basis(x, y, z)
	socket.add_child(light)
	return light


func _make_abort(socket: Node3D) -> Dictionary:
	var core := _taper_ribbon(socket, 2.1, 0.06, 0.20, Color(1.0, 0.97, 0.92, 1.0), Color(1.0, 0.45, 0.12, 0.72), Color(0.40, 0.08, 0.02, 0.0), 0.95, 3, "AbortCore")
	var sheath := _taper_ribbon(socket, 5.2, 0.10, 0.78, Color(1.0, 0.55, 0.18, 1.0), Color(1.0, 0.28, 0.06, 0.55), Color(0.35, 0.06, 0.01, 0.0), 0.82, 3, "AbortSheath")
	return {
		"core": core,
		"sheath": sheath,
		"sparks": _sparks(socket, "AbortCoreSparks", 10, 0.15, 18.0, 28.0, 1.6, 0.05, 6.0),
		"sheath_sparks": _sparks(socket, "AbortSheathSparks", 18, 0.26, 14.0, 22.0, 4.5, 0.09, 8.0),
		"flash": _abort_flash(socket),
		"light": _spot(socket),
	}