Simple Questions About PathFollow2D

kernel_sanders

In the "Your first game" tutorial there is this code:

func _on_MobTimer_timeout():
    # Choose a random location on Path2D.
    $MobPath/MobSpawnLocation.offset = randi()
    # Create a Mob instance and add it to the scene.
    var mob = Mob.instance()
    add_child(mob)
    # Set the mob's direction perpendicular to the path direction.
    var direction = $MobPath/MobSpawnLocation.rotation + PI / 2
    # Set the mob's position to a random location.
    mob.position = $MobPath/MobSpawnLocation.position
    # Add some randomness to the direction.
    direction += rand_range(-PI / 4, PI / 4)
    mob.rotation = direction
    # Set the velocity (speed & direction).
    mob.linear_velocity = Vector2(rand_range(mob.min_speed, mob.max_speed), 0)
    mob.linear_velocity = mob.linear_velocity.rotated(direction)

My questions concern rotation and position properties of MobSpawnLocation (a PathFollow2D node).

1) With this line:

    # Set the mob's direction perpendicular to the path direction.
    var direction = $MobPath/MobSpawnLocation.rotation + PI / 2

My question is, what direction is rotation initially, before I add anything to it?

2) Why does this code:

    # Set the mob's position to a random location.
    mob.position = $MobPath/MobSpawnLocation.position

Set the position to a random location? Is this randomness from the assignment of randi() to .offset?

Thank you

TwistedTwigleg

Welcome to the forums @kernel_sanders!

1) With this line: ... My question is, what direction is rotation initially, before I add anything to it?

The rotation is set initially when you change it's path offset, as the PathFollow2D will rotate to try and stay aligned with the path. It's mentioned briefly in the documentation, but I had too look a couple times to find it so it's easy to miss.

The documentation mentions it right after making the path:

Now that the path is defined, add a PathFollow2D node as a child of MobPath and name it MobSpawnLocation. This node will automatically rotate and follow the path as it moves, so we can use it to select a random position and direction along the path.

That's why the path order is so important, as the rotation code relies on the automatic rotation code in PathFollow2D rotating the node in the correct direction. If you didn't set $MobPath/MobSpawnLocation.offset = randi() before adjusting the rotation, then it wouldn't work, as the rotation wouldn't be automatically set.

2) Why does this code: ... Set the position to a random location? Is this randomness from the assignment of randi() to .offset?

Yup! Setting $MobPath/MobSpawnLocation.offset = randi() will set the location of the PathFollow2D to a random position along the path. Then the code gets the position of the PathFollow2D and uses it as the position for the enemy.