Kinematic object does not detect any collisions - Godot

Question

I am learning Godot game engine and I tried to make a ball that can walk and can't go through other objects, but the ball keep going through the other objects.

Here is the code:

extends KinematicBody2D

export var viteza = 140

func _ready():
    set_fixed_process(true)

func _fixed_process(delta):
    delta *= 5
    var motion = Vector2()

    if Input.is_key_pressed(KEY_UP):
        motion[0] = 0
        motion[1] = -1

    if Input.is_key_pressed(KEY_DOWN):
        motion[0] = 0
        motion[1] = 1

    if Input.is_key_pressed(KEY_LEFT):
        motion[0] = -1
        motion[1] = 0

    if Input.is_key_pressed(KEY_RIGHT):
        motion[0] = 1
        motion[1] = 0

    motion = motion * viteza * delta
    set_pos(get_pos() + motion)

The scene (image): Scene

What is wrong?

Answer 1

Never use set_pos() in a KinematicBody2D. You need to use move().