// SPDX-License-Identifier: MIT
// Copyright (c) 2026 Incoprea
// Project a planned point into a view rectangle
// Not compiled or tested in-world
// Setup: Use a spare owned prim. Set camera pose, point, aspect ratio and FOV between1 and170 degrees. Touch for private calculations.
// Stop / restore: Disable/remove. No camera or object settings are changed.
// Notes: Camera local+X is forward,+Y left,+Z up. Output screen coordinates are rightwardU and downwardV.
// License: see LICENSE in this distribution.
// Original Incoprea. MIT. Transform planning only.
vector CAMERA=<0.0,0.0,2.0>;
vector CAMERA_EULER=ZERO_VECTOR;
vector POINT=<8.0,-2.0,4.0>;
float FOV=60.0;
float ASPECT=1.7777778;
default
{
    touch_start(integer detectedCount)
    {
        if(llDetectedKey(0)!=llGetOwner())return;
        if(FOV<=1.0||FOV>=170.0||ASPECT<=0.0)
        {
            llOwnerSay("Invalid FOV/aspect.");
            return;
        }
        rotation r=llEuler2Rot(CAMERA_EULER*DEG_TO_RAD);
        vector p=(POINT-CAMERA)/r;
        if(p.x<=0.000001)
        {
            llOwnerSay("Point behind camera plane.");
            return;
        }
        float scale=llTan(FOV*DEG_TO_RAD*0.5);
        float x=-p.y/(p.x*scale*ASPECT);
        float y=p.z/(p.x*scale);
        llOwnerSay("ScreenUV="+(string)<(x+1.0)*0.5,(1.0-y)*0.5,0.0>+" depth="+(string)p.x);
    }
}