Best way to create a "screen shake" effect

[Squire Grooktook]

In an effort to make things feel a bit more visceral and violent, I wanted to add a minor "rumble" to certain bombs and events via screen shaking, similar to Imalice's laser.

How would you guys script this? I'm thinking:

Step 1: Take every on screen sprite and object (or alternatively, the screen/camera itself, though the outcome seems the same to me. Whichever is more convenient in your game)
Step 2: Apply a short and small but intense sine wave to their x/y locations (depending on the direction of the rumble)

Any other suggestions for a more organic effect would be appreciated. I'm not really worried about moving all the sprites around, just what kind of movement method would "feel" most like a violent rumble (so in other words, Step 2 ideas/advice?).

[trap15]

If you're shaking the screen, you need to make sure that the player doesn't actually have to do anything precise during that time. In the end, I removed screen shake from my game because it didn't add that much, and it was mostly distracting and annoying.

For the behavior, I did something like:

Code: Select all

// Positions are 8.8 fixed point, angles are 0~0xFF = 0~359 degrees
int mrand(int min, int max);

every_couple_frames() { // iirc it was like every 8th frame, idk, play with it
  // You could shape the shaking by making this more like `tgt_angle + mrand(-7, 7)` or whatever
  angle = mrand(0, 0xFF);
  mag = mrand(0, 0x1000); // tweak this, whatever
  // convert polar to cartesian
  xoff = SQR_DX(angle, mag);
  yoff = SQR_DY(angle, mag);
}
every_frame() {
  scrpos_x = raw_scrpos_x + xoff;
  scrpos_y = raw_scrpos_y + yoff;
  xoff /= 2;
  yoff /= 2;
}

Doing the per-frame halving looks quite nice and makes it feel a lot more comfortable.

[Squire Grooktook]

If you're shaking the screen, you need to make sure that the player doesn't actually have to do anything precise during that time.

Much like the above Imalice example, its during a bomb activation, so precision isn't much of an issue. I was also thinking about using it for certain brief cinematic setpieces (ie have a boss enter by smashing his way up through the floor).

So if I'm reading your code right:

You're moving the screen every frame, and you randomly repick the direction and distance to move it in every 8th (or so) frame. You also reduce the rumble in the interim bewteen each new "rumble" by dividing the the movement by 2.

Correct?

[trap15]

Yeah, exactly. Obviously you can change how often to re-pick the rumble to taste. You could also do some smoothing between re-picks (average the new and previous offsets, for example) to make it a bit less judder-y too.

In the sample code, raw_scrpos is supposed to be the "normal" screen position, and scrpos is for what is actually used.

[Darckonte]

what language are you looking for? I can help you with unity. I make it in my game (https://www.youtube.com/watch?v=jx6IwVkVeEM) I can share the shaking camera script with you if needed

Pasting the code so anyone can benefit, also take into account that you're moving your camera a fixed velocity over time you can use a temp target position to store the new position + the shaking effect:

You can put this into a C# MonoBehavior class, (add variables to make it work).

Code: Select all

         //call it with the intensity you want to shake (small enemies 0.1f , big enemies 0.75f).
        public void OnShake( float amount )
	{
		shakeAmount = amount;
	}
	
	// Update is called once per frame
	void Update () {
		targetPosition += Vector3.up * speed * Time.fixedDeltaTime;

		shake = Vector3.Lerp(shake, new Vector3(Random.value * shakeAmount, Random.value * shakeAmount, 0), 0.25f);

		shakeAmount = Mathf.Lerp(shakeAmount, 0, 6f * Time.fixedDeltaTime);
			
		transform.position =  targetPosition + shake + offset;
	}

[Squire Grooktook]

Thanks for that. I was working in Unity with C#, but I actually transferred over to Game Maker since a lot of other people around here were using it, and it seemed easier if I wanted to ask advice.

So what you're doing there is another variant of random angle and distance offset per frame?

[Darckonte]

Thanks for that. I was working in Unity with C#, but I actually transferred over to Game Maker since a lot of other people around here were using it, and it seemed easier if I wanted to ask advice.

So what you're doing there is another variant of random angle and distance offset per frame?

Yup, basically you lerp your current "random offset" to the next "random offset" and it will give the feeling of shake, doing it smothly with the lerp function.

[Squire Grooktook]

Ah right, I forgot about LERP. Smoothing one offset to another at a time. Interesting. I'll give both of the suggested methods a try later when I have some time to work on this. Thanks to both of you.

[Darckonte]

You're very welcome! good luck in your development

[Rozyrg]

All I do is have specific vars (that remain at 0 normally) added to any background elements' base coordinates. When a shake event is triggered, a timer counts down - with every tick, the variables change: think from say -3 to 3, then return to zero when the timer reaches zero. You want that variation to be consistent between elements, though, and make sure it's all occurring on the same step/frame.

[BPzeBanshee]

Yeah I'd just shake the view_xview/view_yview variables myself. Crude but effective, although I have found with a lot of indie devs they like abusing the shit out of this so I don't use it myself.

[S20-TBL]

Yeah I'd just shake the view_xview/view_yview variables myself. Crude but effective, although I have found with a lot of indie devs they like abusing the shit out of this so I don't use it myself.

Also, if done improperly (i.e. you don't reset your view coordinates to the correct value) the viewport will end up being offset.

[ptoing]

Alternatively to shaking the whole screen you can shake the HUD. Which works well if you got a decently big HUD. SDOJ and some other Cave games do this on boss explosions (maybe bombs too, not sure). It gives a feeling of shaking without fucking with the actual controls. But again, you need quite a bit of HUD, at least a typical Cave one with bombs at the bottom, etc. The SDOJ one with the hyper stuff and counter obviously has even more shit that can be moved around, so it works well.

For Fire Lancer it would not work great since we only got a bit of stuff at the top.

[Squire Grooktook]

I put some of this stuff to use today, and I'm pretty happy with the results. Thanks all