Snippet RandomLocInCircle

[XeNiM666]

I made this out of boredom. Just wanted to test my JASS-ing skills.

This, basically picks a random location in a circle. Thought it might be useful to others.

Just copy this to your map header:

function RandomLocInCircle takes real x_pos, real y_pos, real min_distance, real max_distance returns location
    local location center = Location( x_pos , y_pos )
    local real dis = GetRandomReal( GetRandomReal( min_distance , max_distance / 2.15 ) , max_distance )
    local real ang = GetRandomReal( 0.00 , 360.00 ) * ( 3.14159 / 180.00 )
    local real x = GetLocationX( center ) + dis * Cos( ang )
    local real y = GetLocationY( center ) + dis * Sin( ang )
    call RemoveLocation( center )
    set x_pos = 0.00
    set y_pos = 0.00
    set min_distance = 0.00
    set max_distance = 0.00
    return Location( x , y )
endfunction

And use this function:

RandomLocInCircle( x_coordinate , y_coordinate , min_range , max_range )

Very east

Example of usage: Picks a random location with a maximum range of 700

local location loc = RandomLocInCircle( GetLocationX(udg_Point[1]) , GetLocationY(udg_Point[1]) , 0.00 , 700.00 )

This is my first Snippet so go easy on me and comments are well appreciated!!

~XeNiM666

 

[AceHart]

Well, the distribution of points is not exactly random...

http://www.thehelper.net/forums/showthread.php?t=71314
Post #24 has a couple images on the subject.
Or just read the thread, from post #12 on.


And, yes, if all you need is a couple points... use whatever makes sense to you.

 

[XeNiM666]

But I just tested it.
Wait, i'll add a test map of its usage.

 

[duyen]

Well, the distribution of points is not exactly random...

http://www.thehelper.net/forums/showthread.php?t=71314
Post #24 has a couple images on the subject.
Or just read the thread, from post #12 on.


And, yes, if all you need is a couple points... use whatever makes sense to you.

Nothing is random Ace.

 

[XeNiM666]

UPDATED:

Added a test map of usage

Need more comments.

 

[Darius34]

Well, it's not very practical in the sense that most peope use coordinates; this would require another location to be created, etc. It also uses a BJ function, which could be inlined.

Finally, there's a greater bias towards points the in the centre of the circle with this method.

Nothing is random Ace.

True, but this snippet would be more likely to pick points in the centre even with an ideal RNG.

 

[SerraAvenger]

Well, it's not very practical in the sense that most peope use coordinates; this would require another location to be created, etc. It also uses a BJ function, which could be inlined.

Also, 2 Handle leaks,

True, but this snippet would be more likely to pick points in the centre even with an ideal RNG.

Actually it has the same chance to pick the center like it has to pick one in the outer ring. Just that the outer ring is bigger, and thus the number of picks per area is smaller, resulting in a higher density towards the center.

 

[XeNiM666]

UPDATED:

Increased the random-ness
Removed the BJ

Also, 2 Handle leaks,

what are handle leaks?

 

[Darius34]

Increased the random-ness

Uh, there still is that high density of picks in the centre, because you're using a polar offset. CMIIW

* dis / dis

This doesn't do anything. Also, constants like bj_PI and bj_DEGTORAD don't have to be inlined.

 

[emjlr3]

you're leaving a handle hostage, and as said before, this is exactly not random
also, I'm going to go out on a limb here, but I think storing "180.00 / 3.1415" as a local as opposed to doing the division three time would be faster

 

[AceHart]

> storing "180.00 / 3.1415"

Well, there's a ready to use constant for that, bj_DEGTORAD.
Nothing slow there.
Nothing wrong in using it either.

However, converting twice to radians... that is very random indeed.
And wrong.

The angle should also simply be in radians to begin with...

 

[XeNiM666]

still a noob at JASS, how do i remove the handle leaks?

 

[T.s.e]

Your snippet doesn't leak, it's up to the user to fix the leaks himself.
Like this:

local location l = RandomLocInCircle(..)
call RemoveLocation(l)
set l = null

 

[emjlr3]

it takes a loc that it never removes

 

[XeNiM666]

ok so now i've changed the location to an x,y coordinate.

 

[saw792]

local real x = GetLocationX( Location( x_pos , y_pos ) ) + dis * Cos( ang )
local real y = GetLocationY( Location( x_pos , y_pos ) ) + dis * Sin( ang )

You convert from a real, to a location, then back to that same real. Twice. Hmm.

 

[XeNiM666]

ok now somehow i think i increased the random-ness. it doesnt pick the center more often. also i think i found out the handle leaks??

 

[XeNiM666]

 

[saw792]

function RandomLocInCircle takes real x_pos, real y_pos, real min_distance, real max_distance returns location
    local real dis = GetRandomReal( GetRandomReal( min_distance , max_distance / 2.15 ) , max_distance )
    local real ang = GetRandomReal( -bj_PI , bj_PI)
    local real x = x_pos + dis * Cos( ang )
    local real y = y_pos + dis * Sin( ang )
    return Location( x , y )
endfunction

That's optimised a *little* bit. Lots of useless function calls in there. That isn't the best way to increase the randomness.