The tripwire is an invisible obstacle the player walks through which triggers the boulder to roll
Create a new scene with Area3D as root
Add a CollisionShape3D as child
Select the CollisionShape3D
Add a new script to the TripWire node
Export an array variable so that we can fire
Multiple balls if we want to
Add a variable to check if the trap has sprung
Connect the body entered signal
In the body entered function
If the trap already triggered exit
Check if the player sprung it
Send every projectile towards
Now you can instance tripwires and boulders in the main course level