Widescreen Hack is an emulator feature that make older 3D games playable on 16:9 aspect ratio.
Most video games before mid-2000s were developed for TVs and monitors with 4:3 aspect ratio. If these games are played on 16:9 aspect ratio, the game is either displayed with black bars on each side or streched to fill the whole screen. Some emulators however provide a Widescreen Hack option to make these games look nice on modern monitors.
Some games before mid-2000s do have builtin 16:9 aspect ratio support, but usefulness of this option will vary. Some games just add black bars to top and bottom, while others have very zoomed out camera, so Widescreen Hack may still be useful in these games.
Widescreen Hack basically hacks camera size and position, so depending on the game there might be graphical glitches.
- 2D sprites/HUDs such as Health Bars or Minimaps might look streched or displayed on wrong location.
- Enemies or objects outside of 4:3 area might suddenly appear or disappear, because the game skips rendering of offscreen things. Similaly, the screen-wide visual effects such as fade-in and fade-out may only affect the 4:3 area of the screen.
There are two plugins for Project64 that supports Widescreen Hack.
- Jabo's Direct3D: The versions included in Project64 2.x has a Widescreen Hack option, though the plugin itself is buggy compared to versions came with Project64 1.6 (the version before Widescreen Hack option added). Jabo backported this Widescreen Hack to the 1.6.1 version, which retains the stability of 1.6 with some of the fixes from the other, buggier plugin.
- GLideN64: Currently the only known plugin that can do both Widescreen Hack and Custom Texture Packs, though the system requirement is much higher than Jabo's. As of May 2018, it now has a new "Overscan" feature that lets the users manually edit offsets to remove black borders/lines around the edges of a game's video output and is compatible with any Widescreen Hack.
Dolphin has a Widescreen Hack under Graphics options. The Aspect Ratio option must be set to Force 16:9 to make it work.