Improve trails

scenes/line_trail/line_trail_2d.gd

@@ -0,0 +1,105 @@
+class_name LineTrail2D
+extends Line2D
+
+## Leave a trail behind this node.
+@export var tracking: Node2D
+
+## Minimum distance before adding a new point to the trail line.
+## 0 = always add a new point on each frame.
+@export var min_distance: float = 1.
+
+## Maximum length of the trail before starting to trim.
+## 0 = no length limit.
+@export var max_length: float = 0.
+
+## Maximum lifetime of the trail (in seconds) before starting to trim.
+## 0 = no lifetime limit.
+@export var max_lifetime: float = 3.
+
+# Each index represents the remaining time in seconds before each point is
+# removed from the line, starting to count after the previous point is removed.
+# As an example: [1, 2, 2] means that the first point will be removed in 1
+# second; the second point 2 seconds after the first (so 3 seconds from now);
+# and the third point 2 seconds after the second (so 5 seconds from now).
+var _points_life := PackedFloat32Array()
+
+func _ready() -> void:
+	clear_points()
+
+func _process(delta: float) -> void:
+	global_transform = Transform2D.IDENTITY
+
+	var new_position := tracking.global_position
+
+	# Add new points.
+	var maybe_exceeds_max_length := false
+	if _points_life.size() == 0:
+		_add_point(new_position)
+	else:
+		var last_point := get_point_position(_points_life.size() - 1)
+		var distance_sqr := (new_position - last_point).length_squared()
+		if distance_sqr >= min_distance * min_distance:
+			_add_point(new_position)
+			maybe_exceeds_max_length = true
+
+	# Reduce life and remove expired points.
+	var remove_count := 0
+	if max_lifetime != 0.:
+		_decrease_life(delta)
+		remove_count += _count_expired_points(remove_count)
+
+	# Check if line length exceeds max length.
+	if maybe_exceeds_max_length and max_length != 0.:
+		remove_count += _count_overlength_points(remove_count)
+
+	# Remove expired or overlength points.
+	if remove_count > 0:
+		_remove_oldest_points(remove_count)
+
+func _add_point(point_position: Vector2) -> void:
+	add_point(point_position)
+	
+	var last_point_points_life := 0.
+	for time in _points_life:
+		last_point_points_life += time
+	
+	_points_life.append(max_lifetime - last_point_points_life)
+
+func _remove_oldest_points(remove_count: int) -> void:
+	if remove_count > 0:
+		points = points.slice(remove_count)
+		_points_life = _points_life.slice(remove_count)
+
+func _decrease_life(delta: float, start_at := 0) -> void:
+	var i := start_at
+	while _points_life.size() > i and delta > 0.:
+		var sub = minf(delta, _points_life[i])
+		_points_life[i] -= sub
+		delta -= sub
+		i += 1
+
+func _count_expired_points(start_at := 0) -> int:
+	var i := start_at
+	while i < _points_life.size() and _points_life[i] <= 0.:
+		i += 1
+
+	return i - start_at
+
+func _count_overlength_points(start_at := 0) -> int:
+	var length := 0.
+
+	var all_points := points
+	var previous_point := all_points[start_at]
+	for i in range(start_at + 1, all_points.size()):
+		var point := all_points[i]
+		length += (point - previous_point).length()
+		previous_point = point
+
+	var overlength_count := 0
+	while length > max_length and overlength_count < all_points.size() - 1:
+		var removed_point = all_points[overlength_count]
+		var next_point = all_points[overlength_count + 1]
+		length -= (removed_point - next_point).length()
+		overlength_count += 1
+
+	return overlength_count

scenes/ships_fleet/fading_trail.gdshader

@@ -1,12 +0,0 @@
-shader_type canvas_item;
-
-float rand(vec2 co){
-    return fract(sin(dot(co, vec2(12.9898, 78.233))) * 43758.5453);
-}
-
-void fragment() {
-	if (rand(SCREEN_UV) > COLOR.a - abs(UV.y * 2. - 1.))
-		discard;
-	
-	COLOR = vec4(1., 1., 1., COLOR.a);
-}

scenes/ships_fleet/ship.tscn

@@ -1,22 +0,0 @@
-[gd_scene load_steps=5 format=3 uid="uid://ctybb4niolni3"]
-
-[ext_resource type="Shader" path="res://scenes/ships_fleet/fading_trail.gdshader" id="1_tajfm"]
-
-[sub_resource type="ShaderMaterial" id="ShaderMaterial_ys3et"]
-shader = ExtResource("1_tajfm")
-
-[sub_resource type="PlaceholderTexture2D" id="PlaceholderTexture2D_gcgjo"]
-size = Vector2(12, 4)
-
-[sub_resource type="Gradient" id="Gradient_6a1ig"]
-colors = PackedColorArray(1, 1, 1, 1, 1, 1, 1, 0)
-
-[node name="Ship" type="CPUParticles2D"]
-material = SubResource("ShaderMaterial_ys3et")
-amount = 100
-lifetime = 3.0
-lifetime_randomness = 0.3
-texture = SubResource("PlaceholderTexture2D_gcgjo")
-particle_flag_align_y = true
-gravity = Vector2(0, 0)
-color_ramp = SubResource("Gradient_6a1ig")

scenes/ships_fleet/ship/ship.gd

@@ -0,0 +1,10 @@
+class_name Ship
+extends Node2D
+
+@export var color: Color :
+	set(value):
+		color = value
+		_update_color(color)
+
+func _update_color(ship_color: Color) -> void:
+	%LineTrail.material.set_shader_parameter('color', ship_color)

scenes/ships_fleet/ship/ship.png.import

@@ -0,0 +1,34 @@
+[remap]
+
+importer="texture"
+type="CompressedTexture2D"
+uid="uid://b37ho2wwsaku2"
+path="res://.godot/imported/ship.png-078d321c402a0152c6a650c49954073a.ctex"
+metadata={
+"vram_texture": false
+}
+
+[deps]
+
+source_file="res://scenes/ships_fleet/ship/ship.png"
+dest_files=["res://.godot/imported/ship.png-078d321c402a0152c6a650c49954073a.ctex"]
+
+[params]
+
+compress/mode=0
+compress/high_quality=false
+compress/lossy_quality=0.7
+compress/hdr_compression=1
+compress/normal_map=0
+compress/channel_pack=0
+mipmaps/generate=false
+mipmaps/limit=-1
+roughness/mode=0
+roughness/src_normal=""
+process/fix_alpha_border=true
+process/premult_alpha=false
+process/normal_map_invert_y=false
+process/hdr_as_srgb=false
+process/hdr_clamp_exposure=false
+process/size_limit=8
+detect_3d/compress_to=1

scenes/ships_fleet/ship/ship.tscn

@@ -0,0 +1,31 @@
+[gd_scene load_steps=7 format=3 uid="uid://ctybb4niolni3"]
+
+[ext_resource type="Script" path="res://scenes/ships_fleet/ship/ship.gd" id="1_h6q7s"]
+[ext_resource type="Shader" path="res://scenes/ships_fleet/ship/trail.gdshader" id="2_vgm83"]
+[ext_resource type="Texture2D" uid="uid://dp0ugxgq8stt1" path="res://scenes/ships_fleet/ship/ship_trail.png" id="3_hk6vp"]
+[ext_resource type="Script" path="res://scenes/line_trail/line_trail_2d.gd" id="4_wo8wd"]
+[ext_resource type="Texture2D" uid="uid://b37ho2wwsaku2" path="res://scenes/ships_fleet/ship/ship.png" id="5_fxsfx"]
+
+[sub_resource type="ShaderMaterial" id="ShaderMaterial_bt3sr"]
+resource_local_to_scene = true
+shader = ExtResource("2_vgm83")
+shader_parameter/color = Color(1, 0, 1, 1)
+
+[node name="Ship" type="Node2D"]
+script = ExtResource("1_h6q7s")
+
+[node name="LineTrail" type="Line2D" parent="." node_paths=PackedStringArray("tracking")]
+unique_name_in_owner = true
+material = SubResource("ShaderMaterial_bt3sr")
+points = PackedVector2Array(-128, 0, 0, 0)
+width = 15.0
+texture = ExtResource("3_hk6vp")
+texture_mode = 2
+script = ExtResource("4_wo8wd")
+tracking = NodePath("..")
+max_length = 128.0
+
+[node name="Sprite" type="Sprite2D" parent="."]
+texture_repeat = 1
+texture = ExtResource("5_fxsfx")
+offset = Vector2(1.5, 0.5)

scenes/ships_fleet/ship/ship_trail.png.import

@@ -0,0 +1,34 @@
+[remap]
+
+importer="texture"
+type="CompressedTexture2D"
+uid="uid://dp0ugxgq8stt1"
+path="res://.godot/imported/ship_trail.png-f2252d97e1401056e3019455c7966396.ctex"
+metadata={
+"vram_texture": false
+}
+
+[deps]
+
+source_file="res://scenes/ships_fleet/ship/ship_trail.png"
+dest_files=["res://.godot/imported/ship_trail.png-f2252d97e1401056e3019455c7966396.ctex"]
+
+[params]
+
+compress/mode=0
+compress/high_quality=false
+compress/lossy_quality=0.7
+compress/hdr_compression=1
+compress/normal_map=0
+compress/channel_pack=0
+mipmaps/generate=false
+mipmaps/limit=-1
+roughness/mode=0
+roughness/src_normal=""
+process/fix_alpha_border=true
+process/premult_alpha=false
+process/normal_map_invert_y=false
+process/hdr_as_srgb=false
+process/hdr_clamp_exposure=false
+process/size_limit=0
+detect_3d/compress_to=1

scenes/ships_fleet/ship/trail.gdshader

@@ -0,0 +1,8 @@
+shader_type canvas_item;
+render_mode blend_add;
+
+uniform vec3 color: source_color = vec3(1., 0., 1.);
+
+void fragment() {
+	COLOR = vec4(COLOR.r * color + COLOR.ggg, 1.);
+}

scenes/ships_fleet/ships_fleet.gd

@@ -1,9 +1,9 @@
 extends Node2D
 class_name ShipsFleet
 
-@export var departed_at: float # Time.get_ticks_msec()
+@export var departed_at: int # Time.get_ticks_msec()
 
-@export var arrives_at: float # Time.get_ticks_msec()
+@export var arrives_at: int # Time.get_ticks_msec()
 
 @export var from: Vector2
 
@@ -14,7 +14,7 @@ class_name ShipsFleet
 @export var count: int :
 	set(value):
 		count = value
-		_update__instances_count()
+		_update_instances_count()
 
 @export var trail: Trail
 
@@ -36,14 +36,16 @@ var _instances: Array[Node2D] = []
 
 @export var ship_template: PackedScene
 
-func _update__instances_count() -> void:
+func _update_instances_count() -> void:
 	var diff = count - _instances.size()
 
 	for i in range(diff):
 		var j = float(1 + _instances.size())
-		var ship := ship_template.instantiate()
+		var ship: Ship = ship_template.instantiate()
+		ship.color = player.color
 		add_child(ship)
 		ship.position = Vector2.from_angle(j) * j * 2.
+		ship.look_at(to - from)
 		_instances.push_back(ship)
 
 	for i in range(-diff):
@@ -59,10 +61,9 @@ func _update_position(tick: int) -> void:
 		position = lerp(from, to, smoothstep(0., 1., progress))
 		if tick >= arrives_at:
 			_arrived = true
-			trail.show = false
+			trail.show_trail = false
 
-			for ship in _instances:
-				ship.emitting = false
+			# TODO: fade out ships.
 
 			await get_tree().create_timer(5.).timeout
 			queue_free()

scenes/ships_fleet/ships_fleet.tscn

@@ -1,7 +1,7 @@
 [gd_scene load_steps=3 format=3 uid="uid://cpffyaoh8x5bp"]
 
 [ext_resource type="Script" path="res://scenes/ships_fleet/ships_fleet.gd" id="1_qfy0m"]
-[ext_resource type="PackedScene" uid="uid://ctybb4niolni3" path="res://scenes/ships_fleet/ship.tscn" id="2_6eafk"]
+[ext_resource type="PackedScene" uid="uid://ctybb4niolni3" path="res://scenes/ships_fleet/ship/ship.tscn" id="2_6eafk"]
 
 [node name="ShipsFleet" type="Node2D"]
 script = ExtResource("1_qfy0m")

scenes/trail/trail.gd

@@ -8,9 +8,9 @@ static var _inv_texture_width := NAN
 		color = value
 		_update_color(color)
 
-@export var show: bool = true :
+@export var show_trail: bool = true :
 	set(value):
-		show = value
+		show_trail = value
 		visible = true
 
 @export var auto_free: bool
@@ -36,13 +36,13 @@ func _update_transform(start: Vector2, end: Vector2) -> void:
 		
 	scale = Vector2((end - start).length() * _inv_texture_width, 1.)
 
-func _update_color(color: Color) -> void:
-	var c := Color(color.r, color.g, color.b, color.a * _opacity)
+func _update_color(trail_color: Color) -> void:
+	var c := Color(trail_color.r, trail_color.g, trail_color.b, trail_color.a * _opacity)
 	material.set_shader_parameter('color', c)
 
 func _process(delta: float) -> void:
 	var prev_opacity := _opacity
-	_opacity = Utils.damp(_opacity, 1. if show else 0., 1e-4, delta)
+	_opacity = Utils.damp(_opacity, 1. if show_trail else 0., 1e-4, delta)
 	if _opacity != prev_opacity:
 		if _opacity < .01:
 			_opacity = 0.

scripts/ui/planets_ui.gd

@@ -72,8 +72,8 @@ func _on_planet_pointer_exited(planet: ControlPlanet) -> void:
 #region Trail
 
 func _update_trail(delta: float, snap_position: bool) -> void:
-	_trail.show = _dragging_from_planet and _selected_planet != null and _selected_planet.player is LocalPlayer
-	if _trail.show:
+	_trail.show_trail = _dragging_from_planet and _selected_planet != null and _selected_planet.player is LocalPlayer
+	if _trail.show_trail:
 		_trail.color = _selected_planet.player.color
 		var target_position = _last_cursor_position if _pointed_planet == null else _pointed_planet.global_position
 		_trail.start_position = _selected_planet.global_position