I focused this session on clearing the carry-over bugs from Session 1, adding the thruster VFX system, and writing the first dev log. The game is now properly playable. The player takes damage, bounces off asteroids, rockets explode on impact, and thrusters animate correctly per ship type.

Root Cause: One Size Fits None

The asteroid collision shape was a single CircleShape2D with radius = 210 in local space. After node scale is applied, this becomes:

MEDIUM and SMALL asteroids had invisible collision halos extending well beyond their sprite, which let the player “collide with empty space” and get trapped.

Dynamic Radius from Texture Size

_fit_collision_shape() is called in _ready() after textures load. It derives the collision radius from the actual loaded image dimensions:

func _fit_collision_shape() -> void:
    var img_size: Vector2 = _textures[0].get_size()
    var radius: float = min(img_size.x, img_size.y) * 0.42
    var shape := CircleShape2D.new()
    shape.radius = radius          # local space — scales with node
    collision_shape.shape = shape

Player Bounce Fix

Switched from move_and_collide() to move_and_slide(). This handles multiple simultaneous collisions per frame (asteroid clusters), preventing the “stuck between two rocks” scenario. On asteroid hit, velocity is reflected off the collision normal with 0.6× damping:

func _move() -> void:
    move_and_slide()    # handles multi-collision clusters

    for i in get_slide_collision_count():
        var c := get_slide_collision(i)
        var collider := c.get_collider()
        if collider and collider.is_in_group("asteroids"):
            velocity = velocity.bounce(c.get_normal()) * 0.6  # bounce + dampen
            take_damage()
            break

New scenes/effects/Explosion.tscn + scripts/effects/Explosion.gd. Cycles through 9 frames at ~18fps, then self-destructs. Spawned at bullet world position on impact.

The explosion is added to get_tree().current_scene rather than the bullet’s parent, so it persists for its full duration after the bullet is freed:

func _spawn_explosion() -> void:
    var e: Node2D = _explosion_scene.instantiate()
    get_tree().current_scene.add_child(e)
    e.global_position = global_position   # world position of impact

Thrusters animate through 7 frames at 16fps when the thrust key is held. Each ship variant in a series has a different nozzle configuration. The pattern is consistent across all 3 ship series (CX16, DKO-api, WO84-wu):

Ship Variant Detection

The thruster config is derived from selected_ship % 3. This works because all 3 ship series follow the same X1/X2/X3 pattern:

var variant: int = gm.selected_ship % 3
# 0 → center only (X1)   1 → sides only (X2)   2 → center + sides (X3)
_use_center = (variant == 0 or variant == 2)
_use_sides  = (variant == 1 or variant == 2)

Thruster Nodes in Player.tscn

Animation Loop

func _animate_thrusters(delta: float) -> void:
    if not is_thrusting or _thruster_textures.is_empty():
        return
    _thruster_timer += delta
    if _thruster_timer >= THRUSTER_FRAME_DURATION:   # 0.06s
        _thruster_timer -= THRUSTER_FRAME_DURATION
        _thruster_frame = (_thruster_frame + 1) % 7
        var tex := _thruster_textures[_thruster_frame]
        if _use_center: thruster_center.texture = tex
        if _use_sides:  thruster_left.texture = tex
                        thruster_right.texture = tex

The initial bounce using velocity.bounce(collision_normal) felt wrong and was still causing sticking. The root cause: physics collision normals are unreliable when collision shapes don’t perfectly match the sprite. I replaced it with a centre-to-centre push that matches the wall-bounce behaviour exactly.

Why Collision Normals Fail Here

The Fix: Centre-to-Centre Push

func _bounce_off_body(body: Object) -> void:
    # Direction from body centre → player centre (always correct regardless of shape)
    var push_dir := (global_position - body.global_position).normalized()
    if push_dir == Vector2.ZERO:
        push_dir = Vector2.RIGHT   # exact overlap fallback

    # Preserve speed; guarantee minimum 200 px/s exit velocity
    var speed := maxf(velocity.length(), 200.0)
    velocity = push_dir * speed

    # Physical separation — moves player out of collision zone before next frame
    global_position += push_dir * 6.0

Also extended to enemies group, so the player now bounces off enemy ships the same way.