Added initial support for swapping items between hands

This pull request allows swapping items between hands. The changes will also be necessary when implementing two-handed grabs.

VERSIONS.md

@@ -2,6 +2,7 @@
 - Upgraded project to Godot 4.1 as the new minimum version.
 - Added reporting of stage load errors.
 - Blend player height changes and prevent the player from standing up under a low ceiling.
+- **minor-breakage** Added support for swapping held items between hands.
 
 # 4.2.1
 - Fixed snap-zones showing highlight when disabled.

addons/godot-xr-tools/functions/function_pickup.gd

@@ -373,6 +373,7 @@ func drop_object() -> void:
 
 	# let go of this object
 	picked_up_object.let_go(
+		self,
 		_velocity_averager.linear_velocity() * impulse_factor,
 		_velocity_averager.angular_velocity())
 	picked_up_object = null

addons/godot-xr-tools/functions/function_pickup.tscn

@@ -4,3 +4,4 @@
 
 [node name="FunctionPickup" type="Node3D"]
 script = ExtResource("1")
+grab_collision_mask = 327684

addons/godot-xr-tools/interactables/interactable_handle.gd

@@ -67,9 +67,9 @@ func pick_up(by, with_controller) -> void:
 
 
 # Called when the handle is dropped
-func let_go(_p_linear_velocity: Vector3, _p_angular_velocity: Vector3) -> void:
+func let_go(by: Node3D, _p_linear_velocity: Vector3, _p_angular_velocity: Vector3) -> void:
 	# Call the base-class to perform the drop, but with no velocity
-	super(Vector3.ZERO, Vector3.ZERO)
+	super(by, Vector3.ZERO, Vector3.ZERO)
 
 	# Disable the process function as no-longer held
 	set_process(false)

addons/godot-xr-tools/objects/climbable.gd

@@ -56,7 +56,7 @@ func pick_up(by: Node3D, _with_controller: XRController3D) -> void:
 	handle.global_transform = by.global_transform
 
 # Called by XRToolsFunctionPickup when this is let go by a controller
-func let_go(_p_linear_velocity: Vector3, _p_angular_velocity: Vector3) -> void:
+func let_go(_by: Node3D, _p_linear_velocity: Vector3, _p_angular_velocity: Vector3) -> void:
 	pass
 
 # Get the grab handle

addons/godot-xr-tools/objects/pickable.gd

@@ -54,6 +54,11 @@ enum ReleaseMode {
 	FROZEN = 1,			## Release and freeze
 }
 
+enum SecondHandGrab {
+	IGNORE,				## Ignore second grab
+	SWAP				## Swap to second hand
+}
+
 
 # Default layer for held objects is 17:held-object
 const DEFAULT_LAYER := 0b0000_0000_0000_0001_0000_0000_0000_0000
@@ -80,6 +85,9 @@ const GRIP_POSE_PRIORITY = 100
 ## Method used to perform a ranged grab
 @export var ranged_grab_method : RangedMethod = RangedMethod.SNAP: set = _set_ranged_grab_method
 
+## Second hand grab mode
+@export var second_hand_grab : SecondHandGrab = SecondHandGrab.IGNORE
+
 ## Speed for ranged grab
 @export var ranged_grab_speed : float = 20.0
 
@@ -164,8 +172,24 @@ func _exit_tree():
 
 
 # Test if this object can be picked up
-func can_pick_up(_by: Node3D) -> bool:
-	return enabled and _state == PickableState.IDLE
+func can_pick_up(by: Node3D) -> bool:
+	# Refuse if not enabled
+	if not enabled:
+		return false
+
+	# Allow if the item is idle
+	if _state == PickableState.IDLE:
+		return true
+
+	# Allow swapping the item from one hand to the other
+	if _state == PickableState.HELD and \
+		second_hand_grab != SecondHandGrab.IGNORE and \
+		picked_up_by is XRToolsFunctionPickup and \
+		by is XRToolsFunctionPickup:
+		return true
+
+	# Refuse the pickup
+	return false
 
 
 # Test if this object is picked up
@@ -211,12 +235,17 @@ func drop_and_free():
 
 # Called when this object is picked up
 func pick_up(by: Node3D, with_controller: XRController3D) -> void:
-	# Skip if disabled or already picked up
-	if not enabled or _state != PickableState.IDLE:
+	# Skip if not enabled or range-grabbing
+	if not enabled or _state == PickableState.GRABBING_RANGED:
 		return
 
+	# Skip if held and we don't support second-hand grab
+	if _state != PickableState.IDLE and second_hand_grab == SecondHandGrab.IGNORE:
+		return
+
+	# Drop if currently held
 	if picked_up_by:
-		let_go(Vector3.ZERO, Vector3.ZERO)
+		let_go(picked_up_by, Vector3.ZERO, Vector3.ZERO)
 
 	# remember who picked us up
 	picked_up_by = by
@@ -267,9 +296,9 @@ func pick_up(by: Node3D, with_controller: XRController3D) -> void:
 
 
 # Called when this object is dropped
-func let_go(p_linear_velocity: Vector3, p_angular_velocity: Vector3) -> void:
-	# Skip if idle
-	if _state == PickableState.IDLE:
+func let_go(by: Node3D, p_linear_velocity: Vector3, p_angular_velocity: Vector3) -> void:
+	# Skip if idle or not picked up by the specified node
+	if _state == PickableState.IDLE or by != picked_up_by:
 		return
 
 	# If held then detach from holder

addons/godot-xr-tools/objects/snap_zone.gd

@@ -147,7 +147,7 @@ func pick_up(_by: Node3D, _with_controller: XRController3D) -> void:
 
 
 # Pickable Method: Player never graps snap-zone
-func let_go(_p_linear_velocity: Vector3, _p_angular_velocity: Vector3) -> void:
+func let_go(_by: Node3D, _p_linear_velocity: Vector3, _p_angular_velocity: Vector3) -> void:
 	pass
 
 
@@ -157,7 +157,7 @@ func drop_object() -> void:
 		return
 
 	# let go of this object
-	picked_up_object.let_go(Vector3.ZERO, Vector3.ZERO)
+	picked_up_object.let_go(self, Vector3.ZERO, Vector3.ZERO)
 	picked_up_object = null
 	has_dropped.emit()
 	highlight_updated.emit(self, enabled)

scenes/pickable_demo/objects/grab_ball.tscn

@@ -30,6 +30,7 @@ albedo_color = Color(1, 1, 0, 1)
 [node name="GrabBall" instance=ExtResource("1")]
 collision_mask = 720903
 ranged_grab_method = 2
+second_hand_grab = 1
 
 [node name="GrabPointHandLeft" parent="." index="0" instance=ExtResource("2_qhto0")]
 transform = Transform3D(1, 0, 0, 0, 1, 0, 0, 0, 1, -0.19, 0.04, -0.065)

scenes/pickable_demo/objects/grab_cube.tscn

@@ -17,6 +17,7 @@ size = Vector3(0.1, 0.1, 0.1)
 script = ExtResource("2_xxt38")
 alternate_material = ExtResource("3_g1dne")
 ranged_grab_method = 0
+second_hand_grab = 1
 
 [node name="CollisionShape3D" parent="." index="0"]
 shape = SubResource("7")

scenes/pickable_demo/objects/hammer.tscn

@@ -29,6 +29,7 @@ size = Vector3(0.1, 0.1, 0.2)
 [node name="Hammer" instance=ExtResource("1")]
 collision_mask = 7
 ranged_grab_method = 0
+second_hand_grab = 1
 
 [node name="GrabPointHandLeft" parent="." index="0" instance=ExtResource("2_2myoy")]
 transform = Transform3D(-1, 8.74228e-08, 0, -8.58166e-08, -0.981627, 0.190809, 1.66811e-08, 0.190809, 0.981627, -0.007, 0.355, -0.071)

scenes/pickable_demo/objects/knife.tscn

@@ -71,6 +71,7 @@ points = PackedVector3Array(-0.0142231, 0.0175055, 0.00419341, -0.0142231, -0.01
 [node name="Knife" instance=ExtResource("1")]
 continuous_cd = true
 script = ExtResource("7")
+second_hand_grab = 1
 
 [node name="Knife" type="MeshInstance3D" parent="." index="0"]
 mesh = SubResource("ArrayMesh_anmh6")

scenes/pickable_demo/objects/saucer.tscn

@@ -51,5 +51,6 @@ surface_material_override/0 = ExtResource("1_ycnf3")
 shape = SubResource("ConvexPolygonShape3D_v45tx")
 
 [node name="SnapZoneTeacup" parent="." instance=ExtResource("1")]
+grab_distance = 0.1
 snap_mode = 1
 snap_require = "Teacup"

scenes/pickable_demo/objects/teacup.tscn

@@ -55,6 +55,7 @@ open_pose = ExtResource("7_m23hc")
 closed_pose = ExtResource("7_m23hc")
 
 [node name="Teacup" groups=["Teacup"] instance=ExtResource("1_q232w")]
+second_hand_grab = 1
 
 [node name="Teacup" type="MeshInstance3D" parent="." index="0"]
 gi_mode = 0