local function create_texture(name, w, h, shader)

    name = name .. os.clock()
    shader = shader or "UnlitGeneric"

    local rt = GetRenderTarget(name, w, h, true)
    local mat = CreateMaterial(name, shader)
    mat:SetTexture("$basetexture", rt)

    local obj = {}

    function obj:Start()
        self.old_w = ScrW()
        self.old_h = ScrH()

        self.old_rt = render.GetRenderTarget()
        render.SetRenderTarget(rt)
        render.SetViewPort(0,0,w,h)
        cam.Start2D()

        self.started = true
    end

    function obj:End()
        if not self.started then error("tried to end drawing without starting", 2) return end
        cam.End2D()
        render.SetRenderTarget(self.old)
        render.SetViewPort(0,0, self.old_w, self.old_h)
    end

    function obj:DrawRect(x,y, _w,_h)
        surface.SetMaterial(mat)
        surface.DrawTexturedRect(x, y, _w or w, _h or h)
    end

    function obj:GetMaterial()
        return mat
    end

    function obj:GetTexture()
        return rt
    end

    local id = name .. "_fill"

    function obj:Fill(func)
        hook.Add("Think", id, function()

            self:Start()
                func(w, h)
            self:End()

            hook.Remove("Think", id)
        end)
    end

    return obj
end

local tex = create_texture("main", 256, 16)
local overlay = create_texture("main_overlay", 256, 16)
overlay:Fill(function(w, h)
    render.Clear(0,0,0,0)

    surface.SetDrawColor(256,0,0,255)

    for x = 1, w/2 do
        surface.DrawRect(x*2, 0, 1, h)
    end
end)

surface.CreateFont("lol_console", {font = "System", size = H})

hook.Add("Think", "lol", function()
    tex:Start()
        surface.SetDrawColor(255,0,0,255)
        surface.DrawRect(0,0, 256, 16)

        surface.SetFont("lol_console")
        surface.SetTextPos(0,0)
        surface.SetTextColor(255, 255, 255, 255)
        surface.DrawText("HELLO")
    tex:End()
end)

hook.Add("HUDPaint", "lol", function()
    render.PushFilterMin(1)
    tex:DrawRect(0,0,100*4, 10*4)
    surface.SetDrawColor(255, 255, 255, 100)
    overlay:DrawRect(0,10*16,100*16, 10*16)
    render.PopFilterMin()
end)