startup_loading.vtf is a Valve Texture Format (VTF) file used by the Source Engine (the engine behind games like Half-Life 2 Garry's Mod
Then place startup-loading.vtf in:
garrysmod/materials/vgui/startup-loading.vtf
How to obtain or use a startup-loading.vtf safely and legally
, which is typically a texture file used in Source Engine games (like Counter-Strike: Source, Team Fortress 2, or Garry's Mod) to display a loading screen image.
Here’s how to make a custom startup loading screen feature using your own VTF:
