isPosIn2DArea [function]

[hansen111 12]

So someome asked me how to detect if a position is in a rectangle area without having to use a marker, i searched to give him a link but could not find a small working function, so i wrote and tested one. I thought i share it for anyone in the future searching for the same function:

The functions needs (Parameters):

1) A position, either getPos or getPosATL ect. IMPORTANT - Use the same method (getPos, getPosATL ect.) to get positions of the area and to get postion of player ect

_myPos = getPos player;

2) An array containing 4 positions that makes the box

I used 4 flag objects to test the box:

_myBox = [getPos flag1,getPos flag2,getPos flag3,getPos flag4];

The function returns boolean (true/false) if the position is in the box

So:

_isPlayerInArea = [getPos player,_myBox] call isPosIn2DArea;

isPosIn2DArea = {

//Author: Henrik Hansen

private ["_maxx","_maxy","_minx","_miny","_pos","_box"];

_pos = _this select 0;_box = _this select 1;

_maxx = (_box select 0) select 0;_minx = _maxx;

_maxy = (_box select 0) select 1;_miny = _maxy;

{

if ((_x select 0) < _minx) then {_minx=(_x select 0)};

if ((_x select 0) > _maxx) then {_maxx=(_x select 0)};

if ((_x select 1) < _miny) then {_miny=(_x select 1)};

if ((_x select 1) > _maxy) then {_maxy=(_x select 1)};

} forEach _box;

( ((_pos select 0) <= _maxx) && ((_pos select 0) >= _minx) && ((_pos select 1) <= _maxy) && ((_pos select 1) >= _miny) )

};//function

Here is the test code i used, it will make a hint every second saying on screen if you are in or outside the box:

[] spawn {

private ["_myBox"];

_myBox = [getPos flag1,getPos flag2,getPos flag3,getPos flag4];

while {true} do {

if ([getPos player,_myBox] call isPosIn2DArea) then {hint "In Box"} else {hint "Outside Box"};

sleep 1;

};//while

};//spawn

enjoy

Edited December 21, 2014 by Hansen111

[dreadedentity 278]

Nice work, just curious, how does this function deal with situations like this?

Also, BIS has a function similar to this, BIS_fnc_inTrigger

[hansen111 12]

BIS_fnc_inTrigger uses trigger / trigger area based on marker:

if (typename _trig == typename "") then {_trig = [markerpos _trig,markersize _trig + [markerdir _trig,markershape _trig == "rectangle"]]};

As i said in my post the person making the request of the function did not want to use markers or triggers, but purely position arrays.

As for the Picture you linked to that deals with none 2d regular rectangles which is not in the scope for this function - my function checks for the extremes on x,y axis, so the area check would include positions all the way out to the extreme points, disregarding the center most points.

[Larrow 2823]

BIS_fnc_inTrigger can also do that for you.

It really is a badly named function and should be BIS_fnc_inArea or similar, as it can check for a position inside a trigger, marker or a defined area, it also takes into account the angle of the area aswell so it could be a diamond or a rotated rectangle/ellipse.

//Square, Rectangle or Ellipse
[ [ _areaPos, [ _xSize, _ySize, _angle, _isRectangle ] ], _checkPos ] call BIS_fnc_inTrigger
//Circle
[ [ _areaPos, _radius ], _checkPos ] call BIS_fnc_inTrigger
//Trigger
[ _myTrigger, _checkPos ] call BIS_fnc_inTrigger
//Marker
[ _markerName, _checkPos ] call BIS_fnc_inTrigger

It can also tell you how far from the edge of the area your are if you use the third argument e.g

[ _myTrigger, _checkpos, true ] call BIS_fnc_inTrigger

Will return the distance in meters of how far away you are both inside and outside. Its a negative number if you are inside the area.

Edited December 21, 2014 by Larrow

[hansen111 12]

BIS_fnc_inTrigger can also do that for you.

It really is a badly named function and should be BIS_fnc_inArea or similar, as it can check for a position inside a trigger, marker or a defined area, it also takes into account the angle of the area aswell so it could be a diamond or a rotated rectangle/ellipse.

//Square, Rectangle or Ellipse
[ [ _areaPos, [ _xSize, _ySize, _angle, _isRectangle ] ], _checkPos ] call BIS_fnc_inTrigger
//Circle
[ [ _areaPos, _radius ], _checkPos ] call BIS_fnc_inTrigger
//Trigger
[ _myTrigger, _checkPos ] call BIS_fnc_inTrigger
//Marker
[ _markerName, _checkPos ] call BIS_fnc_inTrigger

It can also tell you how far from the edge of the area your are if you use the third argument e.g

[ _myTrigger, _checkpos, true ] call BIS_fnc_inTrigger

Will return the distance in meters of how far away you are both inside and outside. Its a negative number if you are inside the area.

I missed that function because of its name, never used it either, so how would you use that on a 4 point area like the 4 flag poles like i did? , remember the task was to Work only with 5 positions - 4 positions for the area and 1 for the point to check.

//Square, Rectangle or Ellipse

[ [ _areaPos, [ _xSize, _ySize, _angle, _isRectangle ] ], _checkPos ] call BIS_fnc_inTrigger

If i understand it correctly you would need the 2 lengths and an angle, that would involve 2 distance calculations and an angle calculation?

Edited December 21, 2014 by Hansen111

[dreadedentity 278]

If i understand it correctly you would need the 2 lengths and an angle, that would involve 2 distance calculations and an angle calculation?

Not sure where these calculations come into play, but creating a "virtual zone" that is 10 meters wide and 10 meters tall could not be any simpler than:

_playerPos = getPosATL player;

while {true} do
{
if ([[5,5,0,true], _playerPos] call BIS_fnc_inTrigger) then
{
	hintSilent "You're inside"
}else
{
	hintSilent "You're outside"
};
sleep 0.02;
};

Edited December 21, 2014 by DreadedEntity
realized the loop could never become false

[Larrow 2823]

remember the task was to Work only with 5 positions - 4 positions for the area and 1 for the point to check.

You neglected that fact in the original post "someome asked me how to detect if a position is in a rectangle area without having to use a marker".

If you specifically need to have your area defined by four points rather than position and size then it would hardly be worth it as you would still need to work out the max/min size.

[killzone_kid 1332]

I missed that function because of its name

To be fair the name you gave to your function is pretty inexplicit as well, if not misleading.

[hansen111 12]

To be fair the name you gave to your function is pretty inexplicit as well, if not misleading.

Hmm i dont see that, inTrigger is way way worse because it leads you to think it revolves around arma triggers. 2 out of 4 in this thread thinks inTrigger is terrible, only you have a problem with my function name, so thats fine.

Edited December 21, 2014 by Hansen111

[zapat 56]

I copy Deadfast's function here, which works for all polygons and not only rectangles. Pretty useful, I've been using it for ages.

[color=#FF8040][color=#006400][i]/*
Script by Deadfast.

Using the ray casting algorithm you just cast a line from the point in any direction
and count the number of times it crosses over an edge between two neighboring vertexes.

If the number is odd the point is inside. 

This works for both convex and concave polygons, as long as they are closed.

Input:
_point: position to check
_poly: array containing the positions of poly-vertexes
*/[/i][/color]

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[/color]

Made with KK's SQF to BBCode Converter

[hansen111 12]

If you specifically need to have your area defined by four points rather than position and size then it would hardly be worth it as you would still need to work out the max/min size.

Correct, that was what i was getting at.

I copy Deadfast's function here, which works for all polygons and not only rectangles. Pretty useful, I've been using it for ages.

Thanks zapat, could you include a few examples, that would be great for future readers of the post. Love your Work on getTactical and blackrain btw.

Edited December 21, 2014 by Hansen111