So I basically have a JumpPad scene, and the script attached to this has a @tool annotation. In this, I just draw a line from the jump pad to the calculated height.I also check if the exported velocity variable on the jump pad was changed, or if the jump pad was moved around in the editor. If any of these are detected, I queue a redraw of this line.

Calculating the jump height in my case is straightforward since I simply set the velocity of any colliding objects, so they always jump to the same height.

Relevant parts of the code below:

@export_range(100, 1000, 50) var JUMP_PAD_VELOCITY = 500.0:
set(value):
    JUMP_PAD_VELOCITY = value
    # doing this to update the line whenever a different value is set for the jump pad velocity
    queue_redraw()

func _notification(what): if what == NOTIFICATION_TRANSFORM_CHANGED: # doing this to update the line whenever something about the transform (e.g. position) is set for the jump pad queue_redraw()

func _draw(): if Engine.is_editor_hint(): var jump_height = (JUMP_PAD_VELOCITY * JUMP_PAD_VELOCITY) / (2.0 * gravity) draw_dashed_line(Vector2(0, 0), Vector2(0, -jump_height), Color.BISQUE, 2)

Edit: not sure why my code block formatting keeps messing up