# `CauldronGPU.Sectors.Sky`
[🔗](https://github.com/jaman/cauldron/blob/v0.3.3/cauldron_gpu/lib/cauldron_gpu/sectors/sky.ex#L2)

A sky picture wrapped round the inside of a cylinder, as
`CauldronGPU.Sectors.Surfaces` surfaces keyed `:sky`, laid out as Doom draws its sky:
1024 picture columns to a full turn, one picture row per 1/160 radian of elevation,
row 100 at the horizon. Above and below the picture the cylinder continues in its top
and bottom rows and is closed by caps.

    CauldronGPU.Sectors.Sky.surfaces({x, y, z}, radius, {256, 128})

# `surfaces`

```elixir
@spec surfaces(
  CauldronGPU.Sectors.Surfaces.vec3(),
  number(),
  {pos_integer(), pos_integer()}
) :: [
  CauldronGPU.Sectors.Surfaces.surface()
]
```

The sky cylinder around map point `centre` with `radius`, for a picture of `size`.

---

*Consult [api-reference.md](api-reference.md) for complete listing*