// SPDX-License-Identifier: MIT
// Copyright (c) 2026 Incoprea
// Mirror a child position across a local plane
// Not compiled or tested in-world
// Setup: Use a spare nonphysical rezzed linkset; disable competing scripts and do not edit or relink during the preview. Put this in the root. Set NORMAL and PLANE_POINT. Owner-touch the child to preview; touch again to restore.
// Stop / restore: Owner-touch again to restore before removing, resetting, relinking or transferring. Snapshots are memory-only; deletion/reset does not undo changes. Keep an untouched backup.
// Notes: Mirrors position only; it does not reverse mesh handedness or reflect orientation. The original position, rotation and size are restored together.
// License: see LICENSE in this distribution.
// Original Incoprea. MIT. Test on a spare copy first.
integer selected;
key identity;
list original;
vector NORMAL=<1.0,0.0,0.0>;
vector PLANE_POINT=ZERO_VECTOR;
default
{
    touch_start(integer n)
    {
        if(llDetectedKey(0)!=llGetOwner())return;
        if(llGetAttached()||llGetStatus(STATUS_PHYSICS)||llGetLinkNumber()>1)
        {
            llOwnerSay("Use a nonphysical rezzed root.");
            return;
        }
        if(selected)
        {
            if(llGetLinkKey(selected)==identity)llSetLinkPrimitiveParamsFast(selected,[PRIM_POS_LOCAL,llList2Vector(original,0),PRIM_ROT_LOCAL,llList2Rot(original,1),PRIM_SIZE,llList2Vector(original,2)]);
            else llOwnerSay("Topology changed; restore manually from backup.");
            selected=0;
            return;
        }
        integer link=llDetectedLinkNumber(0);
        if(link<2||link>llGetObjectPrimCount(llGetKey()))
        {
            llOwnerSay("Touch a child prim.");
            return;
        }
        list data=llGetLinkPrimitiveParams(link,[PRIM_POS_LOCAL,PRIM_ROT_LOCAL,PRIM_SIZE]);
        vector p=llList2Vector(data,0);
        rotation r=llList2Rot(data,1);
        vector size=llList2Vector(data,2);
        if(llVecMag(NORMAL)<0.001)return;
        vector normal=llVecNorm(NORMAL);
        p=p-2.0*((p-PLANE_POINT)*normal)*normal;
        selected=link;
        identity=llGetLinkKey(link);
        original=data;
        llSetLinkPrimitiveParamsFast(link,[PRIM_POS_LOCAL,p,PRIM_ROT_LOCAL,r,PRIM_SIZE,size]);
        llOwnerSay("Preview applied; touch again to restore.");
    }
    changed(integer flags)
    {
        if(flags&CHANGED_OWNER)llResetScript();
    }
}