# What Is The Mean Of The " ˜ " Proportional Mathematical Sing In The Movement?

Discussion in 'Technical Discussion' started by JoaoPolido, Aug 22, 2018.

1. ### JoaoPolidoBoxer

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What does the proportional mathematical sign " ˜ " does to the movement liner and angular settings?

Thanks

2. ### Phill MasonSerious Boxer

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Hi @JoaoPolido, I'm not sure what it's called, but I like to think of it as a variable/tolerance. For example, if you set the X axis linear velocity to 50 with a ~ variable of 10, this means that object's velocity will act within the parameters of 40 to 60, ie, 10 above or below the original 50. I've found this useful in a couple of scenarios.

1: Enemies flying towards you from the right of the screen have their usual X velocity, but if you wish to add some randomness to how fast they approach, you can use the variable and this will slow down or speed up their approach. Also, leaving the Y setting at 0 and adding a gentle 2 or 3 variable on the Y axis, will see your enemies approaching and diving or rising from the side, another good random effect.

2: I also like to use the angular velocity in a particle piece. leaving the main setting at 0 and making the ~ variable 359 or even 360, will see particle emanate in a full 360 direction, as apposed to 90 degrees or similar. Leaving the variable set to zero doesn't work as well for a 360 spread, as I imagine BB wants to see something other than zero. This effect looks great for exploding enemies.

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3. ### JoaoPolidoBoxer

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Thanks! Got it

4. ### BobRBoxer

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Essentially the ~ means to add a random + or - value in the range you specify to the first value.