extends ScrollDamper
class_name LinearScrollDamper


## Friction, not physical. 
## The higher the value, the more obvious the deceleration. 
@export_range(0.001, 10000.0, 0.001, "or_greater", "hide_slider")
var friction := 4.0:
	set(val):
		friction = max(val, 0.001)
		_factor = pow(10.0, friction) - 1.0

## Factor to use in formula
var _factor := 10000.0:
	set(val): _factor = max(val, 0.000000000001)


func _calculate_velocity_by_time(time: float) -> float:
	if time <= 0.0: return 0.0
	return time * _factor


func _calculate_time_by_velocity(velocity: float) -> float:
	return abs(velocity) / _factor


func _calculate_offset_by_time(time: float) -> float:
	time = max(time, 0.0)
	return 1.0/2.0 * _factor * time*time


func _calculate_time_by_offset(offset: float) -> float:
	return sqrt(abs(offset) * 2.0 / _factor)