how can I do this? height + height (Solved)

https://krpano.com/docu/actions/#add

You can't simply use opperators like that. You need to either do it in pure JS, or use the math functions like add, which you can find in the documentation.

delayedcall(1,
mul(val, get(plugin[demo].height),2);
tween(plugin[demo].y,get(val));
);

Hi,

you could also calc - e.g.:

tween(plugin[demo].y, calc(plugin[demo].height * 2));

Best regards,
Klaus