Why are the walls in Doom fully 3D, but enemies can only be rendered as 8-directional sprites?

Question

I’ve read that enemies in Doom are rendered as sprites because of hardware limitations. But why is it that walls, stairs, etc. appear fully 3d by contrast?

[example](https://www.youtube.com/watch?v=tDmf9dgso84)

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In: Technology

Answer 1

Its not that it was impossible to make enemies 3D — there just wasn’t enough “polygon budget” left. Rendering the walls took most of the CPU time.

Note, that when there are multiple enemies on screen — their “polygon cost” stacks. If you want many enemies on screen – the polygon count of each must be very low. Doom just goes to an extreme of very low — each enemy uses just 1 polygon.