ShowPlate.cs

using System;
using GTA;
using GTA.Math;
using GTA.Native;

public class SearchCone : Script
{
    public SearchCone()
    {
        Tick += OnTick;
    }

    private bool active = false;

    bool areTheseClose(float h1, float h2, float separation)
    {
        var diff = Math.Abs(h1 - h2);
        if (diff < separation)
            return true;
        if (Math.Abs(diff - 360) < separation)
            return true;

        return false;
    }

    void OnTick(object sender, EventArgs e)
    {
        Ped player = Game.Player.Character;
        if (!player.IsInVehicle())
        {
            return;
        }

        if (Game.IsControlJustPressed(0, Control.VehicleHandbrake))
        {
            active = !active;
            UI.Notify("Plate viewer " + (active ? "enabled" : "disabled"));
        }

        if (!active)
        {
            return;
        }

        Vehicle vehicle = player.CurrentVehicle;
        Vector3 vehPos = vehicle.Position;

        const float searchDist = 30.0f;

        Vehicle[] vehicles = World.GetAllVehicles();

        float closestDist = searchDist;
        string text = "";
        float screenX = 0.0f;
        float screenY = 0.0f;

        for (int i = 0; i < vehicles.Length; i++)
        {
            if (vehicles[i] != vehicle)
            {
                Vector3 targetPos = vehicles[i].Position;
                Vector3 direction = targetPos - vehPos;
                direction.Normalize();
                float vehDirection = Convert.ToSingle(Math.Atan2(direction.Y, direction.X) * (180.0f / Math.PI));
                float myHeading = (player.Heading + 90.0f) % 360;

                OutputArgument x = new OutputArgument();
                OutputArgument y = new OutputArgument();
                bool success = Function.Call<bool>(Hash._WORLD3D_TO_SCREEN2D, targetPos.X, targetPos.Y, targetPos.Z, x, y);
                bool close = areTheseClose(vehDirection, myHeading, 10.0f);
                if (success && close)// && areTheseClose(vehDirection, myHeading, 45.0f))
                {
                    Vector3 plv = player.Position;
                    float dist = World.GetDistance(plv, targetPos);
                    if (dist < searchDist)
                    {
                        if (dist < closestDist)
                        {
                            closestDist = dist;
                            string name = vehicles[i].FriendlyName;
                            string numplate = vehicles[i].NumberPlate;

                            text = "^\n" + name + "\n" + numplate + "\n";
                            screenX = x.GetResult<float>();
                            screenY = y.GetResult<float>();
                        }
                    }
                }
            }
        }
        if (text != "")
        {
            ShowVehicleTag(text, screenX, screenY);
        }
    }

    private static void ShowVehicleTag(string text, float x, float y)
    {
        Function.Call(Hash.SET_TEXT_FONT, 0);
        Function.Call(Hash.SET_TEXT_SCALE, 0.4, 0.4);
        Function.Call(Hash.SET_TEXT_COLOUR, 255, 255, 255, 255);
        Function.Call(Hash.SET_TEXT_WRAP, 0.0, 1.0);
        Function.Call(Hash.SET_TEXT_CENTRE, 0);
        Function.Call(Hash.SET_TEXT_DROPSHADOW, 0, 0, 0, 0, 0);
        Function.Call(Hash.SET_TEXT_EDGE, 1, 0, 0, 0, 205);
        Function.Call(Hash._SET_TEXT_ENTRY, "STRING");
        Function.Call(Hash._ADD_TEXT_COMPONENT_STRING, text);
        Function.Call(Hash._DRAW_TEXT, x, y);
        Function.Call(Hash.DRAW_RECT, x + 0.03f, y + 0.057f, 0.07f, 0.06f, 75, 75, 75, 175);
    }
}