[BUG] Black screen when using OpenGL backend with -warp until seeing sky

[jackrjli]

GZDoom version

4.13.2

Which game are you running with GZDoom?

Doom 2

What Operating System are you using?

Linux x86_64

Please describe your specific OS version

Fedora 41 (also tested on Windows 10)

Relevant hardware info

Nvidia GTX 1070 (also tested with Intel HD Graphics 4000)

Have you checked that no other similar issue already exists?

• I have searched and not found similar issues.

A clear and concise description of what the bug is.

With the rendering API set to OpenGL, loading directly into a map (with -warp or +map) results in a black screen until opening the menu or seeing the sky. For example, -iwad doom2.wad -warp 01 gives a black screen until turning to the left (since there's an outdoor area there), while -warp 05 works immediately since the sky is visible from the start.

I have reproduced this in several different setups:

• Desktop with Nvidia GTX 1070, Fedora 41, GZDoom built from source
• Laptop with Intel HD Graphics 4000, Fedora 41, GZDoom built from source
• Laptop, Fedora 41, GZDoom Flatpak
• Desktop, Windows 10, GZDoom official download

Steps to reproduce the behaviour.

Explain how to reproduce

1. Set rendering API to OpenGL
2. gzdoom -iwad doom2.wad -warp 01

Your configuration

Default config except for vid_preferbackend=0

Provide a Log

No response