// SPDX-License-Identifier: MIT
// Copyright (c) 2026 Incoprea
// Transform a tangent normal into a planned world frame
// Not compiled or tested in-world
// Setup: Use a spare owned prim. Set normalized perpendicular axes T/B/N and TANGENT_NORMAL. Touch for owner-only numeric output.
// Stop / restore: Remove/disable; no colors or materials are applied.
// Notes: The basis must be orthonormal; this example checks perpendicularity and normalizes axes.
// License: see LICENSE in this distribution.
// Original Incoprea. MIT. Color calculation only.
vector T=<1.0,0.0,0.0>;
vector B=<0.0,0.7071068,0.7071068>;
vector N=<0.0,-0.7071068,0.7071068>;
vector TANGENT_NORMAL=<0.2,0.1,1.0>;
default
{
    touch_start(integer detectedCount)
    {
        if(llDetectedKey(0)!=llGetOwner())return;
        if(llVecMag(T)<0.000001||llVecMag(B)<0.000001||llVecMag(N)<0.000001||llVecMag(TANGENT_NORMAL)<0.000001)
        {
            llOwnerSay("Nonzero vectors required.");
            return;
        }
        T=llVecNorm(T);
        B=llVecNorm(B);
        N=llVecNorm(N);
        if(llFabs(T*B)>0.001||llFabs(T*N)>0.001||llFabs(B*N)>0.001)
        {
            llOwnerSay("Axes must be perpendicular.");
            return;
        }
        vector local=llVecNorm(TANGENT_NORMAL);
        llOwnerSay("World normal="+(string)llVecNorm(local.x*T+local.y*B+local.z*N));
    }
}