Initial

Author: Christian

DragDropController.gd

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+extends Node
+
+var current = null
+var drag_offset = Vector2()
+
+var candidates = []
+
+export var drag_group = "draggable"
+
+
+func _ready():
+	var draggables = get_tree().get_nodes_in_group(drag_group)
+	for dragable in draggables:
+		if dragable is CollisionObject2D:
+			dragable.connect("mouse_entered",self,"mouse_entered",[dragable])
+			dragable.connect("mouse_exited",self,"mouse_exited",[dragable])
+			dragable.connect("input_event",self,"input_event",[dragable])
+
+func _process(delta):
+	if current is Node2D:
+		current.global_position = current.get_global_mouse_position() - drag_offset
+
+func mouse_entered(which):
+	candidates.append(which)
+	pass
+
+func mouse_exited(which):
+	candidates.erase(which)
+	pass
+
+func input_event(viewport: Node, event: InputEvent, shape_idx: int,which:Node2D):
+	if event is InputEventMouseButton and event.button_index == BUTTON_LEFT:
+		if event.is_pressed():
+			candidates.sort_custom(self,"depth_sort")
+			var last = candidates.back()
+			if last:
+				last.raise()
+				current = last
+				drag_offset = current.get_global_mouse_position() - current.global_position
+				if current.has_method("on_drag_start"):
+					current.on_drag_start()
+		else:
+			var can_drop = true
+			if current:
+				if current.has_method("on_drop"):
+					var on_drop_result = current.on_drop()
+					can_drop = on_drop_result == null || on_drop_result
+				if can_drop:
+					current = null
+
+func depth_sort(a,b):
+	return b.get_index()<a.get_index()

DragDropController.tscn

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+[gd_scene load_steps=2 format=2]
+
+[ext_resource path="res://DragDropController.gd" type="Script" id=1]
+
+[node name="DragDropController" type="Node"]
+script = ExtResource( 1 )

LICENSE.txt

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+  
+Copyright (c) 2019 Christian Baune.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# Use
+
+1. Add the `DragDropController` node in your scene.
+2. In the inspector, fill in Drag Group with the name of the group containing nodes you want to be draggable, by default, the group is named "draggable".
+3. (optional) In the node that can be dragged, you can create two methods : `on_drop` and `on_drag_start`
+
+## on_drop
+
+Called when the node is dropped. 
+Return "false" to prevent drop.
+Do not return anything (no `return` in your function) or return `true` to allow drop.
+
+Here is an example of implementation to check if you are dropping in a free space:
+
+```godot
+onready var previous_position = position
+func on_drop():
+	position = position.snapped(Vector2(64,64))
+	yield(get_tree(),"idle_frame")
+	yield(get_tree(),"idle_frame")
+	if get_overlapping_areas().size()>0:
+		print("col!")
+		position = previous_position
+	else:
+		print("no col")
+		previous_position = position
+```
+
+## on_drag_start
+
+Called when the node begin to be dragged. (if multiple nodes are stacked, only the topmost node will be dragged)

icon.png

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+[remap]
+
+importer="texture"
+type="StreamTexture"
+path="res://.import/icon.png-487276ed1e3a0c39cad0279d744ee560.stex"
+metadata={
+"vram_texture": false
+}
+
+[deps]
+
+source_file="res://icon.png"
+dest_files=[ "res://.import/icon.png-487276ed1e3a0c39cad0279d744ee560.stex" ]
+
+[params]
+
+compress/mode=0
+compress/lossy_quality=0.7
+compress/hdr_mode=0
+compress/bptc_ldr=0
+compress/normal_map=0
+flags/repeat=0
+flags/filter=true
+flags/mipmaps=false
+flags/anisotropic=false
+flags/srgb=2
+process/fix_alpha_border=true
+process/premult_alpha=false
+process/HDR_as_SRGB=false
+process/invert_color=false
+stream=false
+size_limit=0
+detect_3d=true
+svg/scale=1.0

icon.png.import

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+; Engine configuration file.
+; It's best edited using the editor UI and not directly,
+; since the parameters that go here are not all obvious.
+;
+; Format:
+;   [section] ; section goes between []
+;   param=value ; assign values to parameters
+
+config_version=4
+
+_global_script_classes=[  ]
+_global_script_class_icons={
+
+}
+
+[application]
+
+config/name="DragDrop"
+config/icon="res://icon.png"