"Springy legs" for a First Person Controller in Godot 4

Question

I'm a total beginner, so I barely know what I'm doing, but here goes: I'm using this First Person Starter template and I would like to add a "springy legs" feature on character landing. The higher is the jump, the stronger the springy effect is on landing (but there should probably be a maximum cap value specified).

How can this be achieved?

EDIT: Here's a demonstration of what more or less what I'd like it to feel like: https://youtu.be/dSsV657JYRU

Answer 1

You could use a tween to bounce the camera when you land.

That requires two things:

1. detecting when you land
2. bouncing the camera

Modifying MovementController.gd in the template you're using to something like this might work. It's untested and I'm assuming that the camera always sits at its local position. If it's not working, you'd need to rework it so there's a CameraRoot with a Camera3D child and the system moves the CameraRoot around so we're free to animate the Camera3D.

@export var camera : Camera3D
@export var springy_leg_distance := 0.5
@export var springy_leg_seconds := 0.7

var _was_on_floor := false
var _camera_tween

func _physics_process(delta: float) -> void:
    input_axis = Input.get_vector("move_back", "move_forward", "move_left", "move_right")
    
    direction_input()
    
    if is_on_floor():
        if Input.is_action_just_pressed("jump"):
            velocity.y = jump_height
        if _was_on_floor:
            # (1) At this point, we went from not on floor to on floor, so we
            # want to bounce.
            # We might also want to scale the amount of bounce by our
            # *previous* downward velocity.
            _play_camera_ground_impact()
    else:
        velocity.y -= gravity * delta
    
    accelerate(delta)
    
    # is_on_floor returns a different value after calling move_and_slide
    _was_on_floor = is_on_floor()
    move_and_slide()


func _play_camera_ground_impact():
    # (2) Fire off a tween to bounce the camera to give a springy legs effect.
    if _camera_tween:
        # Prevent two overlapping tweens.
        # You may want to stop if you stop touching the ground too.
        _camera_tween.stop()
    _camera_tween = get_tree().create_tween()
    # Assuming default local position is zero!
    camera.position = Vector3.DOWN * springy_leg_distance # start down a bit
    _camera_tween.tween_property(
            camera,
            "position",
            Vector3.ZERO,                                 # tween back up
            springy_leg_seconds)
    _camera_tween.start()

You could also use an animation to have more control over the motion of the camera.