[3.x] Implement OS agnostic InputEventGesture with Pan, Pinch, and Twist

[jeremyz]

this is shamelessy inspired by Federico-Ciuffardi's job on #36953

I have some ideas to implement thresholds to limit the amount of
emitted events but it will be implemented later.

this to be linked to #13139

[jeremyz]

[gd_scene load_steps=3 format=2]

[ext_resource path="res://icon.png" type="Texture" id=1]

[sub_resource type="GDScript" id=1]
script/source = "extends Node2D

const MAX_ZOOM = 0.5
const MIN_ZOOM = 0.1
onready var cam = $Camera

func _ready():
	cam.zoom.x = 0.2
	cam.zoom.y = 0.2

func _unhandled_input(e):
	if e is InputEventGesturePan:
	        _move(e)
	elif e is InputEventGestureTwist:
	        _rotate(e)
	elif e is InputEventGesturePinch:
	        _zoom(e)

func _move(event):
	cam.offset -= (event.get_delta() * cam.zoom).rotated(cam.rotation)

func _rotate(event):
	var fccp = (event.position - get_camera_center_offset())
	var fccp_op_rot =  - fccp.rotated(event.rotation)
	cam.offset -= ((fccp_op_rot + fccp) * cam.zoom).rotated(cam.rotation - event.rotation)
	cam.rotation -= event.rotation

func _zoom(event):
	var zf = clamp(cam.zoom.x * event.factor, MIN_ZOOM, MAX_ZOOM)
	var zd = zf - cam.zoom.x
	var from_camera_center_pos = event.position - get_camera_center_offset()
	cam.offset -= (from_camera_center_pos * zd).rotated(cam.rotation)
	cam.zoom = zf * Vector2.ONE

func camera2global(position):
	var camera_center = cam.global_position + cam.offset
	var from_camera_center_pos = position - get_camera_center_offset()
	return camera_center + (from_camera_center_pos * cam.zoom).rotated(cam.rotation)

func get_camera_center_offset():
	return get_viewport().get_visible_rect().size / 2
"

[node name="Node" type="Node2D"]
script = SubResource( 1 )

[node name="Sprite" type="Sprite" parent="."]
texture = ExtResource( 1 )

[node name="Camera" type="Camera2D" parent="."]
rotating = true
current = true

[akien-mga]

For the record, I plan to focus on getting #39055 finalized and merged first, then we can update and merge this PR too for 3.5 ideally.

When we get to it though, we might need to change some things for 3.x specifically to avoid breaking compatibility (i.e. keeping the old names for the existing events and just update their implementation + add Twist).

[MuubNito]

For the record, I plan to focus on getting #39055 finalized and merged first, then we can update and merge this PR too for 3.5 ideally.

When we get to it though, we might need to change some things for 3.x specifically to avoid breaking compatibility (i.e. keeping the old names for the existing events and just update their implementation + add Twist).

Dude, im sorry but good luck getting this pr finished anytime...