// SPDX-License-Identifier: MIT
// Copyright (c) 2026 Incoprea
// Estimate diffuse incidence on a planned surface
// Not compiled or tested in-world
// Setup: Use a spare owned prim. Set nonzero NORMAL and TO_LIGHT. Touch for owner-only numeric output.
// Stop / restore: Remove/disable; no colors or materials are applied.
// Notes: This is a Lambertian angular factor only; real lighting also involves distance, materials, shadows and environment.
// License: see LICENSE in this distribution.
// Original Incoprea. MIT. Color calculation only.
vector NORMAL=<0.0,0.0,1.0>;
vector TO_LIGHT=<2.0,1.0,3.0>;
default
{
    touch_start(integer detectedCount)
    {
        if(llDetectedKey(0)!=llGetOwner())return;
        if(llVecMag(NORMAL)<0.000001||llVecMag(TO_LIGHT)<0.000001)
        {
            llOwnerSay("Nonzero vectors required.");
            return;
        }
        float factor=llVecNorm(NORMAL)*llVecNorm(TO_LIGHT);
        if(factor<0.0)factor=0.0;
        llOwnerSay("Diffuse angular factor="+(string)factor);
    }
}