Authors of source code (minetest_game\doors)
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Originally by PilzAdam (MIT)

Modified by BlockMen (MIT): Added sounds, glass doors (glass, obsidian glass) and trapdoor.

Modified by sofar (sofar@foo-projects.org) (MIT):
Added Steel trapdoor.
Re-implemented most of the door algorithms, added meshes, UV wrapped texture.
Added doors API to facilitate coding mods accessing and operating doors.
Added Fence Gate model, code, and sounds.

Various Minetest developers and contributors (MIT)