How do I "ping pong" between 2 numbers without randomization

Shake is one of the simplest things you can do.

Just do it your self using variables, the random() expression, and the system scrollx, and scrolly.

Like:

+> global variable "shake"= 1

-->system scroll x to scrollx+random(-30,30)

-->system scroll y to scrolly+random(-30,30)

This worked.

But I would want to have a stable shake (without random):

(I want scrolly first to add VarNum1 pixels and then subsctract VarNum2 pixels)

I tried:

if shake = 1 --> system scroll y to scrolly+5

--> set shake to 2

if shake = 2 --> system scroll y to scrolly-5

--> set shake to 1

I expected the screen to go go up and down, moving 10 pixels (shake effect). But nothing happened.

By reading that it seems the program is reading it like this: shake = 1 so set shake to 2, now shake = 2 so set shake to 1. Thus it will just stay as shake = 1.

Try using an else, incorporated into the second event, that should ensure it doesn't do both events.

Example capx:

[attachment=0:2yba4cz1][/attachment:2yba4cz1]

Thanks, Sumyjkl

You can use this: system scroll x to scrollx+choose(-30,30)

jastrazz I tried, but action "choose" also uses random.

So it chooses sometimes 1 of the values more than once in a row.

Sumyjkl solved it for me.

You could try the built in shake. Just add the "Scroll to" behavior and then call its shake action.