Simple “yanking” implementation of a grappling hook for VR in Godot

Grapple.gd

extends "res://Tools/UsableObject.gd"

var using = false
onready var ray = $Raycast
onready var hook = $Hook
onready var rope = $Rope
onready var laser = $Laser
onready var indicator = $Indicator
onready var initial_transform = transform
var hook_body = null
var start_origin = null
var target = null
var player = null


func _ready():
    laser.clear()
    laser.begin(1)
    laser.add_vertex(ray.transform.origin)
    laser.add_vertex(ray.cast_to)
    laser.end()


func _physics_process(state):
    if using and target:
        var target_velocity = target - global_transform.origin
        var offset = start_origin - get_parent().get_parent().transform.origin
        player.apply_impulse(Vector3.ZERO, target_velocity.normalized() * 0.5 * offset.length())
    elif player:
        if ray.is_colliding():
            indicator.get_surface_material(0).albedo_color = Color.webgreen
        else:
            indicator.get_surface_material(0).albedo_color = Color.red


func pick_up(by):
    .pick_up(by)
    player = get_parent().player
    ray.enabled = true
    laser.visible = true
    indicator.visible = true


func let_go(impulse=Vector3.ZERO):
    player = null
    unuse()
    laser.visible = false
    .let_go(impulse)
    transform = initial_transform
    mode = RigidBody.MODE_STATIC
    indicator.visible = false
    ray.enabled = false

func use(by):
    using = true

    ray.force_raycast_update()
    if ray.is_colliding():
        hook_body = ray.get_collider()
        start_origin = get_parent().get_parent().transform.origin
        target = ray.get_collision_point()
        hook.visible = true
        laser.visible = false
        remove_child(hook)
        hook_body.add_child(hook)
        hook.global_transform.origin = target
        rope.enabled = true


func unuse():
    using = false
    rope.enabled = false
    hook.visible = false
    laser.visible = true

    if hook_body:
        hook_body.remove_child(hook)
        add_child(hook)
        hook_body = null

    target = null

Grapple.tscn

[gd_scene load_steps=12 format=2]

[ext_resource path="res://Tools/UsableObject.tscn" type="PackedScene" id=1]
[ext_resource path="res://Objects/Grapple.gd" type="Script" id=2]
[ext_resource path="res://Assets/Models/AssetForge/grapple.obj" type="ArrayMesh" id=3]
[ext_resource path="res://Objects/Rope.gd" type="Script" id=4]

[sub_resource type="CylinderShape" id=10]
radius = 0.1
height = 0.3

[sub_resource type="SpatialMaterial" id=4]
albedo_color = Color( 0.278431, 0.278431, 0.278431, 1 )
metallic = 0.47
roughness = 0.63

[sub_resource type="SphereMesh" id=5]
material = SubResource( 4 )
radius = 0.05
height = 0.1
radial_segments = 8
rings = 8

[sub_resource type="SpatialMaterial" id=6]
flags_transparent = true
albedo_color = Color( 1, 0, 0, 0.501961 )

[sub_resource type="SpatialMaterial" id=7]
albedo_color = Color( 0, 0, 0, 1 )
metallic_specular = 0.0

[sub_resource type="PlaneMesh" id=8]
size = Vector2( 0.03, 0.01 )

[sub_resource type="SpatialMaterial" id=9]
resource_local_to_scene = true
albedo_color = Color( 1, 0, 0, 1 )

[node name="Grapple" instance=ExtResource( 1 )]
script = ExtResource( 2 )

[node name="CollisionShape" parent="." index="0"]
transform = Transform( 1, 0, 0, 0, -4.37114e-008, -1, 0, 1, -4.37114e-008, 0, 0, 0.0321951 )
shape = SubResource( 10 )

[node name="grapple" type="MeshInstance" parent="." index="1"]
transform = Transform( 0.1, 0, 0, 0, 0.1, 0, 0, 0, 0.1, -0.034271, 0.0126667, -0.0675699 )
mesh = ExtResource( 3 )
material/0 = null
material/1 = null
material/2 = null
material/3 = null
material/4 = null
material/5 = null
material/6 = null
material/7 = null
material/8 = null
material/9 = null
material/10 = null
material/11 = null
material/12 = null
material/13 = null
material/14 = null
material/15 = null
material/16 = null
material/17 = null

[node name="Raycast" type="RayCast" parent="." index="2"]
cast_to = Vector3( 0, 0, -35 )
collision_mask = 10

[node name="Hook" type="MeshInstance" parent="." index="3"]
transform = Transform( 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0.06 )
visible = false
mesh = SubResource( 5 )
material/0 = null

[node name="Laser" type="ImmediateGeometry" parent="." index="4"]
visible = false
material_override = SubResource( 6 )

[node name="Rope" type="ImmediateGeometry" parent="." index="5"]
transform = Transform( 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0.06 )
material_override = SubResource( 7 )
script = ExtResource( 4 )
start_node = NodePath("..")
end_node = NodePath("../Hook")

[node name="Indicator" type="MeshInstance" parent="." index="6"]
transform = Transform( 1, 0, 0, 0, -4.37114e-008, -1, 0, 1, -4.37114e-008, 0.00157227, 0.0612243, 0.00321842 )
mesh = SubResource( 8 )
material/0 = SubResource( 9 )