local META = FindMetaTable("Player")

local acuracy = 0.95
local min_distance = 30

function META:CanUseNPC()
    return ply:EyePos():Distance(npc:EyePos()) < distance and ply:GetAimVector():DotProduct((npc:EyePos() - ply:EyePos()):Normalize() < acuracy)
end

function GAMEMODE:KeyPress()
    if key == IN_USE then
        for key, npc in pairs(ents.FindByClass("npc*")) do
            if ply:CanUseNPC(npc) then
                GAMEMODE:PlayerUseNPC(ply, npc)
            end
        end
    end
end