using System;

public class Program

{

    public static void Main()

    {

        // config

        // values based on vOS DefaultWindowStyle and spawn behavior outlined in: developer.apple.com/design/human-interface-guidelines/windows#visionOS

        // and recommended 60pt center-to-center element spacing in: developer.apple.com/design/human-interface-guidelines/layout#visionOS

        var panelDistance = 2f;         // meters

        var physicalPanelWidth = 3f;    // meters

        var pointPanelWidth = 1280f;    // points

        var pointPanelHeight = 720f;    // points

        var elementPointWidth = 60f;    // points

        // math

        //  we have the physical panel width and distance from user, so we can trig the angular panel width

        var halfPhysWidth = physicalPanelWidth / 2f;

        var halfPanelFoV = Math.Atan(halfPhysWidth / panelDistance);    // half panel angular width, in radians

        var panelFoV = halfPanelFoV * 2 * (180/Math.PI);    // panel angular width, in degrees

        //  we have the panel point width too, so can get the angular resolution

        var angularResolution = panelFoV / pointPanelWidth; // deg/point

        // that gives us the elements pt to deg conversion

        var elementAngularSize = elementPointWidth * angularResolution; // element angular width

        Console.WriteLine($"Panel angular width: {panelFoV:f2} degrees\n");

        Console.WriteLine($"Angular resolution: {angularResolution:f4} deg/pt, {1/angularResolution:f2} pt/deg\n");

        Console.WriteLine($"Element angular width: {elementPointWidth}pt is {elementAngularSize:f2} deg\n");

        // bonus: how many elements fit in the window width, using DefaultWindowStyle

        var horizElementsPerWindow = Math.Floor(pointPanelWidth / elementPointWidth);

        Console.WriteLine($"Max elements row len: {horizElementsPerWindow}\n");

        // double bonus: what is the derived panel height

        var panelAngularHeight = pointPanelHeight * angularResolution;  // degrees

        var halfPanelAngularHeight = panelAngularHeight * (Math.PI / 180) / 2f; // radians

        var halfPanelPhysicalHeight = Math.Tan(halfPanelAngularHeight) * panelDistance;

        Console.WriteLine($"Panel angular height: {panelAngularHeight:f2} deg\n");

        Console.WriteLine($"Panel physical height: {halfPanelPhysicalHeight * 2f:f2} m\n");

    }

}