+35 votes

I couldn't find a built in screen-shake function, so I implemented the first bit o' logic I found on the internet. Since it's a pretty common feature in games these days, I figured I'd share it. Major features include:

  • Variable duration, frequency, and amplitude.
  • Maintains its own offset so it can be used in combination with other effects.

Since it extends Camera2D, all you have to do to use it is to instance this script instead of base Camera2D then call the shake function. I find that setting the duration, frequency, and amplitude to 0.2, 15, and 8 respectively gives a nice light shaking effect.

extends Camera2D

var _duration = 0.0
var _period_in_ms = 0.0
var _amplitude = 0.0
var _timer = 0.0
var _last_shook_timer = 0
var _previous_x = 0.0
var _previous_y = 0.0
var _last_offset = Vector2(0, 0)

func _ready():
    set_process(true)

# Shake with decreasing intensity while there's time remaining.
func _process(delta):
    # Only shake when there's shake time remaining.
    if _timer == 0:
        return
    # Only shake on certain frames.
    _last_shook_timer = _last_shook_timer + delta
    # Be mathematically correct in the face of lag; usually only happens once.
    while _last_shook_timer >= _period_in_ms:
        _last_shook_timer = _last_shook_timer - _period_in_ms
        # Lerp between [amplitude] and 0.0 intensity based on remaining shake time.
        var intensity = _amplitude * (1 - ((_duration - _timer) / _duration))
        # Noise calculation logic from http://jonny.morrill.me/blog/view/14
        var new_x = rand_range(-1.0, 1.0)
        var x_component = intensity * (_previous_x + (delta * (new_x - _previous_x)))
        var new_y = rand_range(-1.0, 1.0)
        var y_component = intensity * (_previous_y + (delta * (new_y - _previous_y)))
        _previous_x = new_x
        _previous_y = new_y
        # Track how much we've moved the offset, as opposed to other effects.
        var new_offset = Vector2(x_component, y_component)
        set_offset(get_offset() - _last_offset + new_offset)
        _last_offset = new_offset
    # Reset the offset when we're done shaking.
    _timer = _timer - delta
    if _timer <= 0:
        _timer = 0
        set_offset(get_offset() - _last_offset)

# Kick off a new screenshake effect.
func shake(duration, frequency, amplitude):
    # Initialize variables.
    _duration = duration
    _timer = duration
    _period_in_ms = 1.0 / frequency
    _amplitude = amplitude
    _previous_x = rand_range(-1.0, 1.0)
    _previous_y = rand_range(-1.0, 1.0)
    # Reset previous offset, if any.
    set_offset(get_offset() - _last_offset)
    _last_offset = Vector2(0, 0)
asked Feb 27, 2016 in Projects by Hammer Bro. (81 points)
Bookmarked! I'll try it later. Thanks for posting!

2 Answers

+1 vote

Thank you bro, I will use it for sure

answered Feb 28, 2016 by oussama (46 points)
+2 votes

This script is awesome, but I found a small bug. The camera doesn't always return it's offset to origin (0,0), especially when the object the camera is parented to is colliding with something. Also, it processes when it doesn't have to. So I made a few tweaks to improve it for my own needs. Now it only only enables processing while shaking, and disables processing while not shaking. When it's done shaking, it resets the offset to (0,0). And lastly, I made it so you can't interrupt an ongoing shake. Here's the new script: http://pastebin.com/LY52qRE5

answered Mar 6, 2016 by batmanasb (830 points)
edited Mar 6, 2016 by batmanasb

Nice. There is one thing to be aware of: in your modification, by setting the offset to 0,0 at the end of a screenshake effect, you may be interrupting unrelated camera effects.

Imagine you have a system in which you hold Down to look below you, moving the offset some amount. If an explosion shakes the screen while you're looking down, the end of your modified screenshake would re-center the camera on the player unexpectedly.

Fortunately, it's easy enough to tailor the concept to one's specific use cases.

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