POM Silhouettes, 1.17.1 Compatibility, Iris Shaders Mod

OctrayRewrite v0.4.1 is now live in the Discord. This update primarily adds a new feature called "POM Silhouettes", where POM can actually influence the outline of blocks. This is a feature that is only really possible in shaderpacks that have world voxelization, since it uses this information to determine whether a block edge can be seen-through.

I also quietly added "Quadtree POM", which is my new fancy POM algorithm that uses accelerated data structures to raytrace inside high resolution textures a lot faster. Unfortunately, this algorithm has some overhead, and only seems to be beneficial for textures that are 512x or larger. It does make POM raytracing with 2048x texture packs more feasible, from 7 fps to around 20fps on my gtx 1070.

This release also added 1.17.1 compatibility, which was relatively trivial. The minimum required OptiFine version for 1.17.1 is OptiFine HD U H1 pre1.

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POM silhouettes is not perfect, it currently has some outstanding issues where blocks aren't properly detected over chunk boundaries all the time. This causes very ugly see-through lines. I took a stab at fixing this, however I ran into some engine limitations that I could only troubleshoot if I had access to the rendering engine. Because OptiFine is totally closed source, there is nothing I can do. This is a frustratingly common thing that happens in Minecraft shader development, and it led me to look towards alternatives to OptiFine. One promising alternative is the Iris project.

Iris is an open source shader mod that has been in development for about a year. In that time frame it's come pretty close to feature parity with OptiFine, and the fact that it is open source means that I could theoretically tweak the engine myself and experiment with new features. I've wanted to have that kind of access to the game engine for 10 years, so I'm seriously considering porting OctrayRewrite to Iris as soon as possible. OptiFine as a shader platform just moves way to slow to try and develop a state-of-the-art realtime pathtracer.

Iris is currently lacking a few critical features for OctrayRewrite, so I've spent some time (and will spend more) trying to add a few required features. Doing this also gives me some idea of the engine layout of Iris, which will likely be helpful in the future.

I hope Iris turns out to be the open source shaders platform that Minecraft needs. Replacing the rendering engine is a big job, and I've seen other projects (Nova Renderer) try and fail to do basically what Iris has managed in about a year. I am cautiously optimistic.