cannot get collision information using move_and_collide()

Question

I am trying to rotate a kinematic body and then check if the body is colliding using the moveandcollide() function, with 'test_only' as false. However, whenever i attempt to get collision information, it returns an 'invalid get index' or 'null instance' error (depending on how i'm getting this information)

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Here is the code:

func _physics_process(delta):
    CNTRL() #does the movements and stuff
    var testcol = move_and_collide(Vector3(0, 0, 0.1), false, false, true)
    if testcol.testcol.collider().get_collider_id() == "world": # if colliding with the object (in theory)
        print("colliding") #return

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From what i've read everywhere else, i'm not doing anything wrong. Wondering if maybe i've messed up some syntax? Used .collider() and .collider so i dont think its that though.

Answer 1

move_and_collide() returns a KinematicCollision object if there's a collision. When you move and there's no collision, it returns null, which is exactly what your error says.

As explained here:
https://docs.godotengine.org/en/stable/tutorials/physics/using_kinematic_body_2d.html#detecting-collisions

You must check if there even was a collision before trying to access properties of that collision.

There are other problems with your code:

• You wrote testcol.testcol and the KinematicCollision doesn't have a testcol property
• collider is a property of KinematicCollision, not a function
• collider_id is also a property, but it's an int, and so could never be equal to "world"

This could work (not knowing exactly what you're trying to check):

if testcol and testcol.collider.name == "world"