concommand.Add("triangle", function(ply)
  local w = 500
  local h = 500

  local frame = vgui.Create("DFrame")
  frame:SetSize(w, h)
  frame.triangle = {
    { x = w/2, y = 0 },
    { x = w, y = h },
    { x = 0, y = h }
  }
  frame:Center()
  frame:MakePopup()
  frame.Paint = function(pnl, w, h)
    surface.SetDrawColor(20, 20, 20)
    surface.DrawRect(0, 0, w, h)

    draw.NoTexture()
    surface.SetDrawColor(40, 40, 40)
    surface.DrawPoly(pnl.triangle)
  end

  local avatar = vgui.Create("triangleAvatar", frame);
  avatar:SetSize(64, 64);
  avatar:SetPos(w/2 - avatar:GetWide()/2, h/2 - avatar:GetTall());
  avatar:SetPlayer(LocalPlayer(), 128);
  avatar:SetReserve(true);
end)

local function drawTriangle(w, h, reserve)
  local tbl = {}

  if (reserve) then
    tbl = {
      { x = 0, y = 0 },
      { x = w, y = 0 },
      { x = w/2, y = h }
    }
  else
    tbl = {
      { x = w/2, y = 0 },
      { x = w, y = h },
      { x = 0, y = h }
    }
  end

  surface.DrawPoly(tbl)
end
local PANEL = {}

function PANEL:Init()
  self.avatar = vgui.Create( "AvatarImage", self )
  self.avatar:SetPaintedManually( true )
end

function PANEL:PerformLayout()
  self.avatar:SetSize( self:GetWide(), self:GetTall() )
end

function PANEL:SetPlayer( ply, size )
  self.avatar:SetPlayer( ply, size )
end

function PANEL:SetReserve(bool)
  self.avatar.Direction = bool;
end

function PANEL:Paint( w, h )
  render.ClearStencil()
  render.SetStencilEnable( true )

  render.SetStencilWriteMask( 1 )
  render.SetStencilTestMask( 1 )

  render.SetStencilFailOperation( STENCILOPERATION_REPLACE )
  render.SetStencilPassOperation( STENCILOPERATION_ZERO )
  render.SetStencilZFailOperation( STENCILOPERATION_ZERO )
  render.SetStencilCompareFunction( STENCILCOMPARISONFUNCTION_NEVER )
  render.SetStencilReferenceValue( 1 )

  draw.NoTexture()
  surface.SetDrawColor(color_white)
  drawTriangle(w, h, self.avatar.Direction);

  render.SetStencilFailOperation( STENCILOPERATION_ZERO )
  render.SetStencilPassOperation( STENCILOPERATION_REPLACE )
  render.SetStencilZFailOperation( STENCILOPERATION_ZERO )
  render.SetStencilCompareFunction( STENCILCOMPARISONFUNCTION_EQUAL )
  render.SetStencilReferenceValue( 1 )

  self.avatar:PaintManual()

  render.SetStencilEnable( false )
  render.ClearStencil()
end
vgui.Register( "triangleAvatar", PANEL )