// SPDX-License-Identifier: MIT
// Copyright (c) 2026 Incoprea
// Estimate a surface normal from height samples
// Not compiled or tested in-world
// Setup: Use a spare owned prim. Set left/right/down/up heights, positive SPACING and strength. Touch for owner-only numeric output.
// Stop / restore: Remove/disable; no colors or materials are applied.
// Notes: Central differences assume evenly spaced samples. Strength changes slope scale; this does not create a normal-map asset.
// License: see LICENSE in this distribution.
// Original Incoprea. MIT. Color calculation only.
float LEFT=0.2;
float RIGHT=0.5;
float DOWN=0.3;
float UP=0.4;
float SPACING=1.0;
float STRENGTH=2.0;
default
{
    touch_start(integer detectedCount)
    {
        if(llDetectedKey(0)!=llGetOwner())return;
        if(SPACING<=0.0)
        {
            llOwnerSay("Positive spacing required.");
            return;
        }
        float dx=(RIGHT-LEFT)/(2.0*SPACING);
        float dy=(UP-DOWN)/(2.0*SPACING);
        llOwnerSay("Estimated normal="+(string)llVecNorm(<-dx*STRENGTH,-dy*STRENGTH,1.0>));
    }
}