Doom's 2D layer for the graphics card's picture, as RGBA 640 by 400 (Doom's 320 by 200 screen twice over) to be stretched over the frame: during a level the weapon in hand, the border of a smaller view, the status bar, messages and the automap; between levels the tally and the closing text, opaque; and an open menu over all of it. Pixels nothing is drawn on are fully see-through.

rgba = ElixirDoom.Gpu.Overlay.rgba(view, automap: false, seen_key: key, menu: nil, options: %{})

The shimmering pictures of a partly invisible player's weapon are left to ElixirDoom.Gpu.Weapon. Takes the options of ElixirDoom.Render.picture/4.