Calculating Distance from Player

[Zenoff64]

Basically, I want for enemies to know when Im within a certain distance from them, and also when im not within that distance, but also to make sure they're currently on the screen as well, so I can set a flag on or off, for their attack.

And being im mathmatically retarded, I have a hard time figuring this out.

Could anyone post an example or aid me somehow? Many thanks in advance.

[SEELE]

http://www.clickteam.com/epicenter/ubbthreads.php?ubb=showflat&Number=73811#Post73811

This is an example of how to do it, but it is a bit advanced.

[LazyCoder]

@SEELE, sounds to me like all he wants to know is the distance formula.

All you have to do is:
Distance (squared) = (playerx - enemyx) pow 2 + (playery - enemyy) pow 2

For getting the actual distance, just get the square root of that whole expression, but if you're just trying to see if the player is within a certain distance, then just leave it off, and be sure the square the distance you want it to be. Square roots take a long time to calculate, especially if you have many objects.

So if you wanted to check if the enemy was within 100 pixels of the player, just do:
if (playerx-enemyx) pow 2 + (playery-enemyy) pow 2 is less than or equal to 10000 then do actions

10000 is just 100 squared.

EDIT: @SEELE Oh I see what you're getting at, but it sounds to me like he only has 1 player object.

[SEELE]

yes, i get an extension to handle the distance calculation's(since there quicker)and simpler, but yes the idea was multi player and multi enemy handling... I think?

[Jaeu]

The way I do it is make an invisible object that travels in front of and behind the player and the code is something like this

If 'enemy' is overlapping 'invisible object' then go into attack mode (limit this code to once per action)

If 'enemy' is not overlapping 'invisible object' then go into peace mode (limit this code to once per action)

This may be what u r looking for

[SEELE]

There are several holes in that:

For example if a 'second' enemy overlaps while the 'first' is still overlapping the 'second' will be ignored.

Also this requires large objects(never a good idea in mmf(especially with fine detection enabled(such as with sight testing)))

This is also limited to one player at a time, which is a problem most apparently in networked games.

(sorry to be so 'narky')