DmodelPanel Masking Help

[Warmeup]

Hey guys, I recently started working on a new hud to develop my coding skills in glua. Before i continue working on it, I need you guys to tell me how can i use masking on a panel according to a surface.
Just in case you didn't understand what I'm talking about. Here is what i have:

[IMG]http://i.imgur.com/XcwwpGN.jpg[/IMG]
Here is my problem:
[IMG]http://i.imgur.com/NoxqlLh.png[/IMG]
And here is the result I am intending to achieve:
[IMG]http://i.imgur.com/yYzuKLE.png[/IMG]

The circle is a surface in a painted panel and the DmodelPanel is a child to that panel

So, I would like a clear explanation from A to Z about what do i need to do.
Here is a part of my code just in case you need a clearer idea about the structure:

function HPHud()
	

	local hud = vgui.Create('DPanel')

	--skipped some code

	function hud:Paint(w, h)
		
		-- skipped more code


		--function that will draw the circle using drawpoly

                drawCircledBox(false, padw ,padh, 0, radius - 7, 360, nil, nil, Color(0,0,0,255), nil)

	end
	local plymod = vgui.Create('DModelPanel', hud)
	-- skip skip skip
	function plymod:LayoutEntity(ent)
		--skip some more
	end

	function plymod.Entity:GetPlayerColor()
		return pl:GetPlayerColor()
	end
      
        -- skipped more code relate to the eyepos
	
end

[Netheous]

This looks to me like a stencils case.

[Rubat]

There was a bit of code around the forums several times already that does this.

[Warmeup]

Ok, I fixed it using stencils in the paint function of the panel. Thank you for the quick help :D

Edit: For future help, if you are having trouble with the paint function of the dmodelpanel use [URL="https://github.com/garrynewman/garrysmod/blob/master/garrysmod/lua/vgui/dmodelpanel.lua#L115-L150"]this github page[/URL] as a reference to it