[BUG]: Hardware mode does not accurately emulate overscan garbage

[TheTechnician27]

Describe the Bug

On Just Cause, original hardware and software mode accurately display overscan garbage present at the edge of the framebuffer, but hardware mode does not. This would actively make the experience worse, but I'm putting it here as an issue because it reflects an inaccuracy in the HW renderer. (Please don't kill me.)

Reproduction Steps

Play Just Cause and look between original hardware, software renderer, and hardware renderer. (The overscan garbage on OH may be hidden by the borders of the display.)

Expected Behavior

The game should display overscan garbage at the bottom of the framebuffer.

PCSX2 Revision

v2.3.131

Operating System

Linux (64bit) - Specify distro below

If Linux - Specify Distro

Manjaro

CPU

Ryzen 7 5800X

GPU

GTX 1070

GS Settings

Default except High blending accuracy.

Emulation Settings

Default.

GS Window Screenshots

Logs & Dumps

Just Cause_SLUS-21436_20250127125015.7z.zip

[F0bes]

I don't think this is in the scope of the hardware renderers. There are a lot of shortcuts taken to make it fast. Whenever someone writes homebrew I tell them to not rely on hardware mode.

[TheTechnician27]

I don't think this is in the scope of the hardware renderers. There are a lot of shortcuts taken to make it fast. Whenever someone writes homebrew I tell them to not rely on hardware mode.

Yeah, the issue itself isn't about how I really want this specific piece of garbage resolved because my life is a shambles and Sharon took the kids; I just know that a lot of stuff in emudev has a knock-on effect where fixing one thing can fix other things. So I figured it could be worth documenting this oddity in case it's something that somehow turns an otherwise difficult to figure out problem with the HW renderer into one that's easier. For what it's worth, this GS dump also shows off how HW mode renders Just Cause's foliage and how it's a lot different than SW mode (a lot thinner).