// SPDX-License-Identifier: MIT
// Copyright (c) 2026 Incoprea
// Where two circular guides cross
// Not compiled or tested in-world
// Setup: Place in a spare prim. Set centers A/B and positive radii RA/RB. Owner touch prints results without altering the scene.
// Stop / restore: Disable or remove. No prim properties are changed.
// Notes: Coincident centers, separated circles and containment are handled. Tangency produces two equal points within numerical precision.
// License: see LICENSE in this distribution.
// Original Incoprea. MIT. Owner-only calculation.
vector A=<0.0,0.0,0.0>;
vector B=<5.0,0.0,0.0>;
float RA=4.0;
float RB=3.0;
default
{
    touch_start(integer detectedCount)
    {
        if (llDetectedKey(0)!=llGetOwner()) return;
        float distance=llVecDist(A,B);
        if(RA<=0.0||RB<=0.0||llFabs(A.z-B.z)>0.0001)
        {
            llOwnerSay("Use positive radii and equal Z planes.");
            return;
        }
        if(distance<0.000001)
        {
            llOwnerSay("Coincident centres: no unique pair.");
            return;
        }
        if(distance>RA+RB||distance<llFabs(RA-RB))
        {
            llOwnerSay("No crossing.");
            return;
        }
        float x=(RA*RA-RB*RB+distance*distance)/(2.0*distance);
        float h2=RA*RA-x*x;
        if(h2<0.0)h2=0.0;
        vector direction=(B-A)/distance;
        vector base=A+x*direction;
        vector side=<-direction.y,direction.x,0.0>*llSqrt(h2);
        llOwnerSay("Crossings "+(string)(base+side)+" and "+(string)(base-side));
    }
}