compsci_godot_albert/_subsections/sec05/lesson-06.org

#+title: Section 05 - Lesson 06 | Plane Movement
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* Links
- [[../../toc.org][TOC - Godot Notes]]
- [[https://www.udemy.com/course/jumpstart-to-2d-game-development-godot-4-for-beginners/learn/lecture/50356747#overview][S05:L06 - video]]

* Notes
- the more complex the collision shape the more computations
- if you concentrate on good games, you'll notice the collisions are actually straightforward

** collision shape
*** adding a collision shape
- click on root node
- add child CollisionShape2D
  - pane scene->collision_shape_2D
  - pane inspector->CollisionShape2D->Shape
    - select new CircleShape2D
    - use shape handles to adjust

*** issues with collisions
- we want the collision shape to be good
- but the more complex the collision the more computations
- focus on the game flow, not perfecting the modeling


*** circle shape resource
- click inside the Shape dropdown on the CircleShape2D item
- it will open up and show you details about CircleShape2D
  - radius
  - resource
    - local to scene
    - path
    - name

- currently the resource is embedded in the scene

**** if you want to save the resource for reuse
- click on the arrow next to the Shape dropdown
- click save or save as

** add a script
- SELECT THE ROOT NODE "plane"
- click on the Scene green plus to add a script
 #+attr_html: :width 600
 file:../../_share/media/img/albert/section-05/lesson-06/ex_01a.png

*** in dialog
- template: select Node default
- built in script: off

*** coding
- in a phsycis body we just give vectors
  - let the physics engine deal with positioning

- CharacterBody2D has a velocity variable which you can set
  - Vector2D velocity
    - x, y
    - how much we want to move in x and y

  - function bool move_and_slide()
    - updates our position
    - updates the velocity if we collide with something

  - after move_and_slide has been invoked we call other funcitons
    - is_on_ceiling
    - is_on_floor
    - etc

- upDirection method sets what is "up"
  - default x: 0, y: -1
  - (0, 1) ceiling is now floor
  - (1, 0) the left side is the ceiling

*** default gravity
- you can access gravity from Project Settings

#+begin_src gdscript
var _gravity: float = ProjectSettings.get("physics/2d/default_gravity")
#+end_src

*** manipulating physics nodes
- use _physics_process instead of _process

- process is invoked every frame
- physics process is invoked at about half that rate

** creating boundaries
*** create barrier scene
**** initialize the scene
- create a new scene
- don't select one of the default nodes as the root
- use the + symbol in Scene to select a StaticBody2D as the root node

**** add boundaries
- create 2 CollisionShape2D nodes
- on each set shape to WorldBoundaryShape2D

- lower node
  - move the boundary to the bottom of the viewing area

- top node
  - move the boundary a little bit above so as to give the plane some room to bounce through the ceiling
  - click on the Shape dropdown of WorldShape2D to open additional values
    - set the direction to down
    - in Normal, change y from -1 to 1, so it points down instead of up

- save scene

*** add barrier to game scene
- instantiate as a child node in the game scene