Show HN: Monte Carlo ray tracer in Rust

We're now approaching the point where raytracing is the simpler, easier, faster alternative. It's also great for artists because the results are more predictable. Raytracing gives a better result, or simply makes it possible for things like good shadows, transparency, reflection and global illumination.

It might take a while, but the current way of doing things is a dead end. If a triangle is smaller than a pixel, you're basically just raytracing anyway. That's also becoming a more common thing these days. There will continue to be hybrid solutions for a while, but as raytracing takes over certain portions of the rendering, which it is good enough for already, there is no reason to go back.

Rasterized graphics can do specular reflections quite well as long as the reflection only shows things that are currently in view. One can then perform a limited form of ray tracing in the depth buffer to detect which part of the screen is visible where in the reflection. However, as soon as we want to reflect things outside of the screen it gets tricky, as we can't simply perform this screen space ray tracing. Instead, we have to rely on pre-baked reflection map textures. This works well enough for static objects, like the environment, but you can't see dynamic content, like players, as they can't be pre-baked into the texture. Also, it's useless when there are no static objects, like in Minecraft where there's no such thing as a static environment -- every block can change dynamically. And this is where the limit of specular reflections of rasterization is basically hit. There are of course workarounds, like rendering the scene a second time from the mirrors perspective, and then combining the view render and the mirror render, but you can imagine it gets prohibitively expensive quite fast as you add a few more reflective objects to the scene. Also, this method doesn't work for glossy reflections -- that's even more complex.

So this is just one example of how rasterized graphics limits us -- we can't have more than a few reflective objects in a scene which features dynamic geometry, which is a very sensible thing to want to have!

In my opinion, ray tracing really is that much better than the approximations we've developed. Also consider how much faster / cheaper it would be for a studio to create new graphics engines when you only have to write 1000 lines of ray tracing code instead of 100'000 lines of rasterization hacks (for a worse-looking result!).