godot-3bp

extends Node2D

@export var simulation_speed: float = 1.0
@export var orbit_scale: float = 150.0
@export_enum("Figure-8", "Lagrange Triangle", "Butterfly") var orbit_pattern: int = 0
@export var trail_length: int = 75
@export var trail_width: float = 6.0
@export var glow_intensity: float = 2.5

var bodies: Array = []
var body_visuals: Array = []
var time: float = 0.0
var center: Vector2

class Body:
    var angle: float
    var orbit_radius: float
    var orbit_speed: float
    var phase: float
    var color: Color
    var trail_points: Array = []

    func _init(a: float, r: float, s: float, p: float, c: Color):
        angle = a
        orbit_radius = r
        orbit_speed = s
        phase = p
        color = c

func _ready():
    center = get_viewport_rect().size / 2.0
    setup_orbital_system()
    await get_tree().process_frame
    create_visual_effects()

func setup_orbital_system():
    bodies.clear()
    match orbit_pattern:
        0:
            bodies.append(Body.new(
                0.0, orbit_scale * 0.8, 1.2, 0.0,
                Color(1.0, 0.5, 0.2, 1.0)
            ))
            bodies.append(Body.new(
                TAU * 0.33, orbit_scale * 0.8, 1.2, TAU * 0.33,
                Color(0.2, 0.7, 1.0, 1.0)
            ))
            bodies.append(Body.new(
                TAU * 0.66, orbit_scale * 0.8, 1.2, TAU * 0.66,
                Color(1.0, 1.0, 0.3, 1.0)
            ))
        1:
            for i in range(3):
                var angle = (i * TAU / 3.0)
                bodies.append(Body.new(
                    angle, orbit_scale, 1.0, 0.0,
                    [Color(1.0, 0.3, 0.3), Color(0.3, 1.0, 0.5), Color(0.5, 0.5, 1.0)][i]
                ))
        2:
            bodies.append(Body.new(
                0.0, orbit_scale * 0.6, 1.5, 0.0,
                Color(1.0, 0.2, 0.6, 1.0)
            ))
            bodies.append(Body.new(
                PI, orbit_scale * 0.6, 1.5, PI,
                Color(0.2, 1.0, 0.8, 1.0)
            ))
            bodies.append(Body.new(
                PI * 0.5, orbit_scale * 1.0, 0.8, 0.0,
                Color(0.8, 0.8, 1.0, 1.0)
            ))

func create_visual_effects():
    for i in range(bodies.size()):
        var body = bodies[i]

        var container = Node2D.new()
        container.name = "Body" + str(i)
        add_child(container)

        var light = PointLight2D.new()
        light.enabled = true
        light.color = body.color
        light.energy = glow_intensity
        light.texture_scale = 1.0
        light.blend_mode = Light2D.BLEND_MODE_ADD
        container.add_child(light)

        var particles = CPUParticles2D.new()
        particles.emitting = true
        particles.amount = 100
        particles.lifetime = 0.8
        particles.local_coords = false
        particles.emission_shape = CPUParticles2D.EMISSION_SHAPE_SPHERE
        particles.emission_sphere_radius = 5.0

        particles.gravity = Vector2.ZERO
        particles.initial_velocity_min = 3.0
        particles.initial_velocity_max = 10.0
        particles.linear_accel_min = -15.0
        particles.linear_accel_max = -20.0
        particles.damping_min = 10.0
        particles.damping_max = 15.0

        particles.scale_amount_min = 2.0
        particles.scale_amount_max = 4.0
        particles.color = body.color

        container.add_child(particles)

        var trail_line = Line2D.new()
        trail_line.width = trail_width
        trail_line.default_color = body.color
        trail_line.joint_mode = Line2D.LINE_JOINT_ROUND
        trail_line.begin_cap_mode = Line2D.LINE_CAP_ROUND
        trail_line.end_cap_mode = Line2D.LINE_CAP_ROUND
        trail_line.antialiased = true

        add_child(trail_line)

        var glow_line = Line2D.new()
        glow_line.width = trail_width * 2.5
        var glow_color = body.color
        glow_color.a = 0.3
        glow_line.default_color = glow_color
        glow_line.joint_mode = Line2D.LINE_JOINT_ROUND
        glow_line.begin_cap_mode = Line2D.LINE_CAP_ROUND
        glow_line.end_cap_mode = Line2D.LINE_CAP_ROUND
        glow_line.antialiased = true

        add_child(glow_line)

        body_visuals.append({
            "container": container,
            "light": light,
            "particles": particles,
            "trail_line": trail_line,
            "glow_line": glow_line
        })

func _process(delta):
    time += delta * simulation_speed
    update_bodies()
    update_visuals()

func update_bodies():
    for i in range(bodies.size()):
        var body = bodies[i]

        body.angle += body.orbit_speed * 0.02

        var x_offset = cos(body.angle + body.phase) * body.orbit_radius
        var y_offset = sin(body.angle + body.phase) * body.orbit_radius * 0.85

        if orbit_pattern == 0:
            var figure8_offset = sin(body.angle * 2.0) * orbit_scale * 0.3
            x_offset += figure8_offset

        var position = center + Vector2(x_offset, y_offset)

        body.trail_points.push_front(position)
        if body.trail_points.size() > trail_length:
            body.trail_points.resize(trail_length)

func update_visuals():
    for i in range(bodies.size()):
        var body = bodies[i]
        var visuals = body_visuals[i]

        if body.trail_points.is_empty():
            continue

        var pos = body.trail_points[0]

        visuals["container"].global_position = pos

        var pulse = 1.0 + sin(time * 3.0 + i * TAU / 3.0) * 0.2
        visuals["light"].energy = glow_intensity * pulse

        var trail_line = visuals["trail_line"]
        trail_line.clear_points()

        var num_points = min(body.trail_points.size(), trail_length)
        for j in range(num_points):
            trail_line.add_point(body.trail_points[j])

        var glow_line = visuals["glow_line"]
        glow_line.clear_points()
        for j in range(0, num_points, 3):
            glow_line.add_point(body.trail_points[j])

func reset_simulation():
    for body in bodies:
        body.trail_points.clear()
        body.angle = randf() * TAU
    time = 0.0

func change_pattern(pattern_index: int):
    orbit_pattern = pattern_index

    for visual in body_visuals:
        visual["container"].queue_free()
        visual["trail_line"].queue_free()
        visual["glow_line"].queue_free()

    body_visuals.clear()
    bodies.clear()

    setup_orbital_system()
    await get_tree().process_frame
    create_visual_effects()