compsci_godot_albert/_subsections/sec05/lesson-06.org

Section 05 - Lesson 06 | Plane Movement

• Links
• Notes
  • collision shape
    • adding a collision shape
    • issues with collisions
    • circle shape resource
      • if you want to save the resource for reuse
  • add a script
    • in dialog
    • coding
    • default gravity
    • manipulating physics nodes
  • creating boundaries
    • create barrier scene
      • initialize the scene
      • add boundaries
    • add barrier to game scene

Links

• TOC - Godot Notes
• 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

  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

var _gravity: float = ProjectSettings.get("physics/2d/default_gravity")

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