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#+title: Lesson 12: Player-Enemy Collisions


* Links
- [[../../arpg/toc.org][< Back to Main TOC]]
- [[https://youtu.be/WVQkOWY3zxQ?si=UILX6fBQ_Zw1cZoK][Player-enemy collision]]



* Notes
** add collision shape to enemy sprite
- add CollisionShape2D to sprite root

*** add shape
- select collision shape 2D node from Scene Panel
- Go to Inspector->CollisionShape2D->Shape
- select 'CapsuleShape2D' from dropdown

*** modify shape
- Inspector->CollisionShape2D->Node2D->Transform
- Go to Rotation and set to 90 degrees
- Modify shape via handles to adjust it over sprite

*** set the z-index
- in CollisionShape2D to 0
- in sprite root node to 1

*** make sure collision shape fits all the animation frames
- go to the AnimateSprit2D node
- Inspector->AnimatedSprite2D->Animation->Frame
- scroll through the frames to see if they fit the collision shape properly

** modify the player script to handle the collision

*** default collision code
- default collision handling occurs between two CharacterBody2D nodes
- limits each others movements
- occurs after the =move_and_slide= function is called

#+begin_src godot
# Using move_and_collide.
var collision = move_and_collide(velocity * delta)
if collision:
    print("I collided with ", collision.get_collider().name)
#+end_src

*** handle collisions (scaffolding)
- first get the number of collisions that occurred
  - this is in =get_slide_collision_count()= function
- loop through the number with an index
  - in each loop get the /collision info object/ for that index with =get_slide_collisions()=
    - =get_slide_collision= takes an index
  - to get the /collider/ call =get_collider()= on the /collision info object/

- the function scaffolding:
#+begin_src godot
# this is the basic function
func handleCollision():
    for i in get_slide_collision_count():
        var collision = get_slide_collision(i)
        var collider = collision.get_collider()
        priint_debug(collider.name)
#+end_src

- place this function in =func _physics_process(delta)=
  - put it after =move_and_slide= but before =updateAnimation=
  - example:
#+begin_src godot
func _physics_process(delta):
    handleInput()
    move_and_slide()
    handleCollision()
    updateAnimation()
#+end_src

* Video Contents

[[https://www.youtube.com/watch?v=WVQkOWY3zxQ][Lesson Link]]

#+attr_html: :class content
- [[https://www.youtube.com/watch?v=WVQkOWY3zxQ][00:00 Introduction]]
- [[https://youtu.be/WVQkOWY3zxQ?si=vhyjv3xTfYhvAMmE&t=28][00:28 body-body collision]]
- [[https://youtu.be/WVQkOWY3zxQ?si=qLZquUVuAC-yYN1t&t=238][03:57 layer and mask]]
- [[https://youtu.be/WVQkOWY3zxQ?si=GqVUob9wQvm1YH_9&t=298][04:58 hurt boxy and hit box]]
- [[https://youtu.be/WVQkOWY3zxQ?si=rhqR5crCcWh7vgSH&t=394][06:34 hit box animation]]
- [[https://youtu.be/WVQkOWY3zxQ?si=DIBeG4TRZdhcds0g&t=711][11:51 fixing move animation]]
- [[https://youtu.be/WVQkOWY3zxQ?si=CTRznDX_bRokCO0d&t=751][12:31 hurt-hit box collisions]]
- [[https://youtu.be/WVQkOWY3zxQ?si=fUUy5KhrAFLzbWdA&t=827][13:47 outro]]