Morlet wavelet for gunshut camera effect (for PROs only!!)

3absh

I'm trying to make the camera shake in a "Morlet wavelet"

so that when the player shoots camera bounces up, then goes down lesser, then up again lesser then down then stops.

I found this wave but the function I found was kind of confusing to implement here in GS.

https://en.wikipedia.org/wiki/Morlet_wavelet

3absh

Note:
wave must start at zero (Y axis), then go up from there

jamie_c

@3absh, I'm sure if @socks were still around he could whip this up, he was a master of sin curves and such. You might try searching the forums if you haven't already. There were a few great tutorials posted about sin curves and GS. They probably wouldn't be this exactly but they might help in understanding how to accomplish something like this.

adent42

So wavelets be a bit more work and I'm not 100% sure how they would impact performance. If I remember right, wavelets are basically summations of various wave functions (wavelets). That form the more complex wave that can't be gotten by a simple function.

So what I can think of is multiplying a bell curve like function (for intensity) with a sine or cosine at the frequency you want.

I googled "trig approximation of bell curve" and got:

f(x) = (1/2pi) * (1 + cos x)

A simplifed sine wave function is:

A * sin(B * x) where A is the amplitude and B is the frequency.

So the expression you're looking for is:

(1 / (2 * 3.1459)) * (1 + cos x)) * sin(b * x)

x should be either time (for shake) or actor.position.x (when you're visualizing the function by making an actor move across the scene).

b should be adjusted to get the right shake frequency you're looking for.

I don't have time right now to whip up an example, but hopefully someone here beats me to it!

Hope that helps!

RThurman

Here is a camera shake that might be close.

jamie_c

@RThurman, that's nice.

3absh

Wow, guys I'm overwhelmed with the fast and AMAZING response.
Thanks @adent42 @RThurman This is EXACTLY what I'm looking for

Now, just to make things a little more challenging & interesting.

My "default" camera isn't really constant. It's moving around in a very subtle x & y sin wave

So I'm trying to make the "Morlet wavelet" ease back into the sin wave instead of zero.

I can use a timer and interpolate for the transition but there will be an ugly jolt effect, and the code I believe won't be as efficient.

3absh

This is very close to my final result,

I added timers to ease in the transition between the morlet wave and the default camera movement.

Although there is a slight disturbing jolt at the end that I need to get rid of.

3absh

Same sample but with a smaller jolt at the end

RThurman

Try this one. It combines a bunch of separate functions into one long equation.

Technically, this is not a morlet wavelet. A morlet wave starts small, builds up, and then dissipates (as shown in the graph above). But a gun shot does not build up in the beginning. It just kicks. So.... this equation just simulates the second half of the graph.

3absh

@RThurman that's awesome, this whole shotting wave function just opened up a wide range of possibilities for me.

RThurman

@jamie_c -- thanks! (We are still using your excellent GameSalad book by the way.)

@3absh -- glad it will work for you! You are correct that using the function can be applied in a wide range of situations. For more information, look up "Hooke's Law".

RThurman

@3absh -- here is a link for a presentation I gave on Hooke's law. It includes a camera shake demo, and some other fun stuff.
https://forums.gamesalad.com/discussion/comment/560025/#Comment_560025

smurfted

excellent