// SPDX-License-Identifier: MIT
// Copyright (c) 2026 Incoprea
// Point inside an irregular boundary
// Not compiled or tested in-world
// Setup: Place in a spare prim. Set ordered boundary POINTS and test P. Owner touch prints results without altering the scene.
// Stop / restore: Disable or remove. No prim properties are changed.
// Notes: Boundary points are not assigned a special inside/outside guarantee; use a distance-to-edge tolerance when boundaries matter. Z is ignored.
// License: see LICENSE in this distribution.
// Original Incoprea. MIT. Owner-only calculation.
list POINTS=[<0.0,0.0,0.0>,<5.0,0.0,0.0>,<5.0,2.0,0.0>,<2.0,2.0,0.0>,<2.0,5.0,0.0>,<0.0,5.0,0.0>];
vector P=<1.0,3.0,0.0>;
default
{
    touch_start(integer detectedCount)
    {
        if (llDetectedKey(0)!=llGetOwner()) return;
        integer n=llGetListLength(POINTS);
        if(n<3)
        {
            llOwnerSay("Need three or more vertices.");
            return;
        }
        integer inside=FALSE;
        integer i;
        integer j=n-1;
        for(i=0;i<n;++i)
        {
            vector a=llList2Vector(POINTS,i);
            vector b=llList2Vector(POINTS,j);
            if((a.y>P.y)!=(b.y>P.y))
            {
                float crossing=(b.x-a.x)*(P.y-a.y)/(b.y-a.y)+a.x;
                if(P.x<crossing)inside=!inside;
            }
            j=i;
        }
        llOwnerSay("Inside (excluding boundary ambiguity): "+(string)inside);
    }
}