Godot 3 changes in physics

NeoD

I'm migrating my scripts and it is harder than I expected. I understand the need for API breaking if the changes make the developer life easier, or if the game will be better, but in the physics code I discover several additionnal concepts shape owners and kinematic collision objects, who just make my migration more exhausting and my scripts more complicated. Maybe I will discover others things during my migration. The owner shape is the parent collision object, why specify it again ? The collision data inside the Kinematicbody was fine, why separate this in his own object ? Someones know what's the point of this added complexity ?

Ace_Dragon

How much you have to change depends on whether or not you abused the Godot design flaw that allowed a script to extend from a class other than the type of node the script was attached to. This was seen as a bug and was fixed for Godot 3.1.

To fix, just change the top line to "extends (type of node the script is attached to)" and make sure you get the requisite node first before executing a function from a different class.

That said, you can still execute functions from any class the node inherits (such as object, node, ect...).

NeoD

My scripts types seems to be correct. In Godot 2, the shapes are accessed by the physic body node (Kinematic, Area etc..) you can add shape, remove or change dimensions etc...You use an ID because a physic body may have several shapes. In Godot 3, shapes are accessed by a mysterious owner, "who are not nodes" according to the description. You must create it and retreve these ID and use it for operations on the shapes. The call must have two int arguments instead of one. Like the OpenGL C "black box" or something low level. I was used to think by attaching every resource to a node, and for me a shape is simply attached to a physicbody. So I'm confused now. Simple "get_shape" is still available in the "Collision Shape" Node, but not in the physic body nodes (who was very logical for me). But I assume CollisionShape nodes exists only in editor ! Why this change ?

NeoD

To illustrate the change here is a script who add a shape to a physic body in Godot 3.

extends KinematicBody2D

export (float) var radius = 100
export (Color) var ballColor = Color(1, 1, 1)
onready var shapeOwnerID = create_shape_owner(self)
    
func _ready():
	shape_owner_add_shape(shapeOwnerID, CircleShape2D.new())
	shape_owner_get_shape(shapeOwnerID, 0).set_radius(radius)

func _draw():
	draw_circle(Vector2(0, 0), radius, ballColor)

And the same task but in Godot 2. Straightforward isn't it ?

extends KinematicBody2D

export (float) var radius = 100
export (Color) var ballColor = Color(1, 1, 1)
    
func _ready():
	add_shape(CircleShape2D.new())
	get_shape(0).set_radius(radius)

func _draw():
	draw_circle(Vector2(0, 0), radius, ballColor)