Trying to determine if vector point is within an area.

[Alexis Iskast]

I am trying to figure out how to detect if an avatar X and Y location is within an L shaped area.  I've seen it done before but curious on how this is being done.

 

list protect_x = [233.365100,223.688900,223.688900,228.208000,228.208000,233.365100];
list protect_y = [214.940700,214.940700,208.975000,208.975000,204.834500,204.834500];
vector getPos(key owner)
{
vector pos = llList2Vector(llGetObjectDetails(owner, [OBJECT_POS]),0);
return pos;
}

default
{
touch_start(integer total_number)
{
key id = llDetectedKey(0);
vector pos = getPos(id);
llOwnerSay("Your current position: "+(string)pos);
float x = (float)pos.x;
float y = (float)pos.y;
llOwnerSay("X: "+(string)x+" Y: "+(string)y);
integer len = llGetListLength(protect_x);
integer i = 0;
integer j = 1;
integer G = FALSE;
while (j < len)
{

if (x > llList2Float(protect_x,i) && x < llList2Float(protect_x,j) && y > llList2Float(protect_y,i) && y < llList2Float(protect_y,j))
{
G=TRUE;
}
++i;
++j;
}
if (G == TRUE) { llSay(0,"You're in protected area");} else { llSay(0,"You're not in protected area");}
}
}

 

The area is an L shaped area.  Just really hung up on this one :\

[Stickman Ingmann]

Last time I encountered this problem it was very simple. I had to find out if the point x, y was within a 2D rectangle. While I was digging for that, I found several more complex situations, such as finding out if a point is within a 2D polygon, if a line passes through (or just in) an n-sided polygon, etc.

I'm sure a Google search can help you find the math you're looking for.

A search led me here:

http://www.ecse.rpi.edu/Homepages/wrf/Research/Short_Notes/pnpoly.html

This looks like a 2D test. But it could be modified to run multiple times. Four, I think, with two sides of each rectangle making up the L shape would do the job.

Math is not my strong suit. Especially not 3D math. Something I'm still learning. But the problem you're seeking the answer to is not new, and has been documented countless times. Finding the math for it is just a matter of finding the official terminology used to describe such a situation.

[Innula Zenovka]

https://wiki.secondlife.com/wiki/IsPointInPolygon2D might help.

[Alexis Iskast]

thanks, that actually worked...that C code, converted it to LSL and wham bam!  -- Made one of the most complex shape ever and it detected me inside it at every point.