Iris was created to fill a void that I saw in the Minecraft
customization and graphical enhancement community: the lack of an
open-source shaders mod that would let me load my favorite shader
packs on modern versions of the game, while retaining performance and
compatibility with modpacks. OptiFine, the current dominant mod for
loading shader packs, has restrictive licensing that firmly stands in
the way of any sort of tinkering, and is fairly notorious for having
compatibility issues with the mods that I like. It's also
mutually incompatible with Sodium, the best rendering optimization mod
in existence by a large margin. ShadersMod was never updated past
1.12, and it lacks support for many of the many modern popular
shaderpacks. So I created Iris, to try and solve these issues, and
also address many other longstanding issues with shader packs.
I first and foremost develop Iris to meet my own needs of a performance-oriented shaders mod with good compatibility and potential for tinkering. Iris when paired with Sodium delivers great performance on my machine, finally making it fully possible for me to actually play with shaders instead of just periodically switching them on to take pretty screenshots, then switching them off once I get tired of frame drops. Of course, as it turns out, I'm far from the only person who benefits from the development of Iris, which is why I've decided to release it to the public as an open-source mod.
Iris has a public stable release for both 1.16 and 1.17 that work with a custom version of Sodium, and a public beta release for 1.18 snapshots. Iris is still in heavy development and gets new improvements every week, and is progressing very rapidly!
Vanilla Minecraft has a very old codebase, and many say that it is in sore need of a rewrite, especially when it comes to graphics. Blaze 3D rendering, added in 1.15, was an attempt to alleviate this somewhat, but in many ways only worsened the problem. In 1.17, Minecraft is moving to OpenGL Core 3.2 and Java 16, but so far no significant changes have been implemented that utilize the performance enhancements of these systems. Minecraft before 1.17 also did not natively support shaders, and even since 1.17 released, shader support is very limited. However, Minecraft is known for its low-overhead minimalistic graphics, and provides a strong foundation for high-performance shader-based graphics.
Sodium is a fabric mod that rewrites parts of the vanilla rendering system to optimize for performance in a way that no other mod has done before. Sodium is actively maintained and updated, and aims to be compatible with most other Fabric mods for maximum FPS even in the densest modpacks. Its sibling mods, Lithium, Phosphor, and Hydrogen, can all be used in conjunction with sodium to each optimize a different aspect of the game, whether it be ticking, lighting, or memory respectively. These mods together can boost FPS to 150% or more of vanilla performance for any player out there, whether you're aiming for maximum frames to give you that PvP edge, or whether Sodium and the like are the only mods that can make the game playable on the hardware you have at hand.
Iris builds on both Sodium and Vanilla by providing something that no standalone fabric mod has before: support for existing custom shaders. And because Iris stacks with Sodium and Vanilla, you can get shaders at remarkable frame rates, without the need for expensive hardware or experimental game modifications. The extra processes that iris performs only reduce performance by 10-15 percent, and with sodium installed the performance stays well above vanilla performance. In the future, Iris will be fully integrated and streamlined, and will even have rendering optimizations of its own, allowing Sodium and Iris together to be better than either of them alone. And these performance increases transfer directly to shaders, with most popular shaders consistently running at or above 60 fps, even on 5 and 6 year old hardware!