Skybox/horizon discrepancy between hardware & software

[whirledtsar]

https://imgur.com/K9tEf3v
https://imgur.com/a/KklFwo5
Yes I know theres an [imgur] tag. If only it worked.

Anyways, the top screenshot is the software renderer. The bottom is the hardware renderer.
The walls of the skybox sector are line_horizon, because they arent meant to be seen.
The borders of the level are also line_horizon. In software, it renders the skybox into infinity where the walls would be. But in hardware, it renders the skybox differently on the wall, so theres a noticeable (and undesirable) divide between the sky and horizon.

Test map, Hexen UDMF format: https://cdn.discordapp.com/attachments/ ... 98/tst.wad

[Graf Zahl]

Your problem is with the 3D floor in there. Using Line_Horizon on a sector with a 3D floor is undefined - the hardware renderer does not render it at all, and the results for the software renderer are generally unpredictable - in this simple case it just happens to work as intended.

[whirledtsar]

Why not render it like the ceiling is? Cost on performance?

[Graf Zahl]

It's not that simple. Horizons are a relatively natural and straightforward thing in the software renderer, but in the hardware renderer require setting up a portal - and the entire setup does not work with planes that are not either the top and bottom of the entire scene.