Bullet VS Skia

For typical game physics engines... not that much. Math libraries like Eigen or Blaze use lots of template metaprogramming techniques under the hood that can help when you're doing large batched matrix multiplications (since it can remove temporary allocations at compile-time and can also fuse operations efficiently, as well as applying various SIMD optimizations), but it doesn't really help when you need lots of small operations (with mat3 / mat4 / vec3 / quat / etc.). Typical game physics engines tend to use iterative algorithms for their solvers (Gauss-Seidel, PBD, etc...) instead of batched "matrix"-oriented ones, so you'll get less benefits out of Eigen / Blaze compared to what you typically see in deep learning / scientific computing workloads.

The codebases I've seen in many game physics engines seem to all roll their own math libraries for these stuff, or even just use SIMD (SSE / AVX) intrinsics directly. Examples: PhysX (https://github.com/NVIDIA-Omniverse/PhysX), Box2D (https://github.com/erincatto/box2d), Bullet (https://github.com/bulletphysics/bullet3)...

I suspect most C++ physics libraries like Box2D (https://github.com/erincatto/box2d) or Bullet3 (https://github.com/bulletphysics/bullet3) could really benefit a lot from SIMD.

No, they replaced Bullet with Jolt. That is considerably more than "some adjustment", regardless of what you think of the result.

Vulkan graphics via Intel GVK, and physics via Bullet

The first two have a bunch of great examples, and I’m tying them together by refactoring some of the THREE examples to fit the ECS paradigm defined in AFrame. then upping the ante by adding physics using AMMO, which is more challenging since it’s only a partial implementation of Bullet, and already poorly documented (yet popular) physics engine.

Plus, SM uses a system called bullet physics, I imagine this would be rather complex to rework into a modern engine such as Unreal or Unity (after all, the majority of performance issues come from the physics engine rather than the graphics engine)

The physics in HDT-SMP are actually being calculated outside of Skyrim's engine with Bullet, an open-source physics engine. So this isn't some limitation of Skyrim's engine.

Actually, that's not entirely accurate. The lottie-web library itself doesn't support rendering to WebGL. However, there is a package called canvaskit-wasm that wraps Skia (a graphics engine) with WebAssembly (wasm). This package includes a module called skottie which supports rendering animations into a WebGL surface. However, there is a drawback with this approach: using wasm requires loading a relatively large package, and it's uncertain whether all features are supported correctly, as the official compatibility table that tracks lottie support on different platforms does not include skottie.

Skia is pretty great if you can get it running.

The imgs are mainly used by Tencent QQ and Baidu Tieba users. QQ and Tieba compress imgs by default, so the popular imgs (in China we call them "屌图" or "表情包") would be compressed million of times during the spreading, causing the super low quality. These APPs on Android are using Skia for image processing, which suffering from a legendary bug: result would be more green. The bug was fixed in 2016: https://github.com/google/skia/commit/c7d01d3e1d3621907c27b283fb7f8b6e177c629d

There’s also Skia by Google. Used by Android and Google Chrome.