An Interactive 2D3D button library for Garry's Mod.

cl_Interactive2D3D.lua

local Interactive2D3D = {}
Interactive2D3D.IsVisible = function(self) return (self.Visible or false) end
Interactive2D3D.Start = function(self, vPos, aRot, vScale)
	if !vPos or !aRot then return false end
	self.Valid = true
	local plpostoscreenx = vPos.x - LocalPlayer():GetShootPos().x
	local plpostoscreeny = vPos.y - LocalPlayer():GetShootPos().y
	local plpostoscreen = math.sqrt( plpostoscreenx^2+plpostoscreeny^2 )
	local dist1 = 1/( math.cos( math.rad( EyeAngles().y ) ) ) * plpostoscreen
	local distfull = 1/( math.cos( math.rad( EyeAngles().p ) ) ) * dist1
	local trace = {}
	trace.start = LocalPlayer():GetShootPos()
	trace.endpos = LocalPlayer():GetAimVector() * distfull + trace.start
	trace.filter = LocalPlayer()
	local tr = util.TraceLine( trace )
	if tr.Entity and IsValid(tr.Entity) then self.Visible = false return false end
	self.Visible = true
	local test = trace.endpos
	local vWorldPos=test-vPos;
	vWorldPos:Rotate( Angle( 0, -aRot.y, 0 ) );
	vWorldPos:Rotate( Angle( -aRot.p, 0, 0 ) );
	vWorldPos:Rotate( Angle( 0, 0, -aRot.r ) );
	self.EyeHitx = (vWorldPos.x/(vScale or 1))
	self.EyeHity = ((-vWorldPos.y)/(vScale or 1))
	return true
end
Interactive2D3D.Finish = function(self)
	if !self:IsVisible() then return false end
	return self:Remove()
end
Interactive2D3D.Use = function(self, Name)
	if !self:IsVisible() then return false end
	if !Name and self.Buttons then
		for _,v in pairs(self.Buttons) do
			if self:Use(v.Name) then if (v.LastClick or 0) < CurTime() then if v.DoClick then self:Remove(v.Name) v:DoClick() v.LastClick = CurTime()+0.1 return v.Name end end break end
		end
	else
		if !self.Buttons or !self.Buttons[Name] then return false end
		return self.Buttons[Name]:IsHovered()
	end
end
hook.Add( "KeyPress", "Interactive2D3DKeyPress", function( _, key ) if ( key == IN_USE ) then Interactive2D3D:Use() end end )
Interactive2D3D.Remove = function(self, Name)
	if Name and self.Buttons and self.Buttons[Name] then
		self.Buttons[Name] = nil
	else
		self.Buttons = {}
		self.Visible = false
		self.Valid = false
	end
	return true
end
Interactive2D3D.MakeButton = function(self, x, y, w, h , Name)
	if !Name or !self.Valid then return false end
	self.Buttons = self.Buttons or {}
	if self.Buttons[Name] then
		if self:IsVisible() and self.EyeHitx and self.EyeHity then
			if (self.EyeHitx < w-(x*-1)) and (self.EyeHitx > x) and (self.EyeHity < h-(y*-1)) and (self.EyeHity > y) then
				if !self.Buttons[Name].Hovered then self.Buttons[Name].Hovered = true end
			else 
				if self.Buttons[Name].Hovered then self.Buttons[Name].Hovered = false end
			end
			if self.Buttons[Name].Paint then self.Buttons[Name]:Paint(x, y, w, h) end
		end
		return self.Buttons[Name]
	end
	local Button = {}
	Button.Name = Name
	Button.Hovered = false
	Button.IsHovered = function(this) return this.Hovered or false end
	Button.Remove = function(this) return self:Remove(this.Name) or false end
	Button.Pos = {x = (x or 0), y = (y or 0), w = (w or 0), h = (h or 0)}
	Button.GetPos = function(this) return this.Pos or {} end
	self.Buttons[Name] = Button
	return Button
end

function cam.EndInteractive3D2D() cam.End3D2D() end
function cam.StartInteractive3D2D(vector, angle, scale, distance) -- This is a helper function to replace Start3D2D.
	if distance then
		if vector:Distance(LocalPlayer():GetPos()) < distance then
			cam.Start3D2D( vector, angle, scale )
			Interactive2D3D:Start(vector, angle, scale )
        else
			Interactive2D3D:Finish()
		end
	else
		cam.Start3D2D( vector, angle, scale )
		Interactive2D3D:Start(vector, angle, scale )
	end
end

Example:

hook.Add( "PreDrawOpaqueRenderables", "ButtonTest", function()
    local vector = Vector(0,0,0)
    local distance = 1000
    if vector:Distance(LocalPlayer():GetPos()) < distance then
        local angle = Angle(0,0,0)
        angle:RotateAroundAxis( angle:Forward(), 90 )
        angle:RotateAroundAxis( angle:Right(), 90 )
        cam.StartInteractive3D2D( vector, angle, 0.1, distance ) -- This is a wrapper for Start3D2D, you see the code if you don't want to use it.
            local TestButton = Interactive2D3D:MakeButton(0, 0, 100, 100, "TestButton") -- Make a 3D2D button (x, y, w, h, UniqueName)
            TestButton.DoClick = function(self) -- When the button is pressed.
                print(self.Name.." Was Pressed!")
            end
            TestButton.Paint = function(self, x, y, w, h) -- This is a helper function, you don't need to actually render inside this.
                draw.RoundedBox( 0, x, y, w, h, Color( 255, 255, 255, 255 ) )
                if self:IsHovered() then draw.RoundedBox( 0, x, y, w, h, Color( 0, 0, 0, 255 ) ) end
            end
        cam.EndInteractive3D2D()
    end
end )

Preview:

Result when pressed with Use(E):

TestButton Was Pressed!