godot-demo-projects/2d/physics_platformer/enemy/enemy.gd

class_name Enemy extends RigidBody2D


const WALK_SPEED = 50

enum State {
	WALKING,
	DYING,
}

var _state := State.WALKING

var direction := -1
var anim := ""

var Bullet := preload("res://player/bullet.gd")

@onready var rc_left := $RaycastLeft as RayCast2D
@onready var rc_right := $RaycastRight as RayCast2D


func _integrate_forces(state: PhysicsDirectBodyState2D) -> void:
	var velocity := state.get_linear_velocity()
	var new_anim := anim

	if _state == State.DYING:
		new_anim = "explode"
	elif _state == State.WALKING:
		new_anim = "walk"

		var wall_side := 0.0

		for collider_index in state.get_contact_count():
			var collider := state.get_contact_collider_object(collider_index)
			var collision_normal := state.get_contact_local_normal(collider_index)

			if collider is Bullet and not (collider as Bullet).disabled:
				_bullet_collider.call_deferred(collider, state, collision_normal)
				break

			if collision_normal.x > 0.9:
				wall_side = 1.0
			elif collision_normal.x < -0.9:
				wall_side = -1.0

		if wall_side != 0 and wall_side != direction:
			direction = -direction
			($Sprite2D as Sprite2D).scale.x = -direction
		if direction < 0 and not rc_left.is_colliding() and rc_right.is_colliding():
			direction = -direction
			($Sprite2D as Sprite2D).scale.x = -direction
		elif direction > 0 and not rc_right.is_colliding() and rc_left.is_colliding():
			direction = -direction
			($Sprite2D as Sprite2D).scale.x = -direction

		velocity.x = direction * WALK_SPEED

	if anim != new_anim:
		anim = new_anim
		($AnimationPlayer as AnimationPlayer).play(anim)

	state.set_linear_velocity(velocity)


func _die() -> void:
	queue_free()


func _pre_explode() -> void:
	#make sure nothing collides against this
	$Shape1.queue_free()
	$Shape2.queue_free()
	$Shape3.queue_free()

	($SoundExplode as AudioStreamPlayer2D).play()


func _bullet_collider(
	collider: Bullet,
	state: PhysicsDirectBodyState2D,
	collision_normal: Vector2
) -> void:
	_state = State.DYING

	state.set_angular_velocity(signf(collision_normal.x) * 33.0)
	physics_material_override.friction = 1
	collider.disable()
	($SoundHit as AudioStreamPlayer2D).play()