> The game uses ray casting, not ray tracing. Ray casting is when you send a ray once for every column of pixels
Both ‘ray casting’ and ‘ray tracing’ are overloaded terms, the distinction isn’t as clear as you suggest. You’re talking about 2d ray casting, but 3d ray casting is common, and means to many people the same thing as ‘ray tracing’. Ray casting “is essentially the same as ray tracing for computer graphics”. https://en.wikipedia.org/wiki/Ray_casting
There’s also Whitted-style recursive ray tracing, and path tracing style ray tracing, but ray tracing in it’s most basic form means to test visibility between two points, which is what ray casting also means from time to time.
I've given up on the semantics of "ray-tracing", everyone has their own opinion. However it's fairly common for "ray-casting" to mean non-recursive, and the wiki article you link explicitly says this.
I think the biggest difference between ray-type algorithms is everything vs ray-marching, because regardless of recursion, and strategies towards lighting, texture sampling and physical realism, with ray-marching a single ray is not really a ray at all but lots of little line segments, and you don't usually bother finding explicit and intersections which gets really complex and expensive... that's the whole point, instead you find proximity or depth, which means you can render implicit surfaces like fractals.
Yes, ray casting does not ever imply recursion, it’s simply referring to casting a ray to test visibility from one point to another. Ray tracing now most commonly means exactly the same thing, and expecting anything else will often lead to confusion.
“Ray marching” is also overloaded ;) but what you’re referring to (also and originally called ‘sphere tracing’) is a new and separate idea from either ray casting or ray tracing (if you’re thinking of something other than ray casting when you say that.) Ray casting/tracing is most often done using non-iterative analytic intersection functions, where the style of ray marching you’re referring to is a distance field query, not a point to point visibility query, so ”ray marching” generally implies a different traversal algorithm, and (usually) a different representation of the geometry.
You can use any/all of these to build path tracers, but they come with different tradeoffs.
Both ‘ray casting’ and ‘ray tracing’ are overloaded terms, the distinction isn’t as clear as you suggest. You’re talking about 2d ray casting, but 3d ray casting is common, and means to many people the same thing as ‘ray tracing’. Ray casting “is essentially the same as ray tracing for computer graphics”. https://en.wikipedia.org/wiki/Ray_casting
There’s also Whitted-style recursive ray tracing, and path tracing style ray tracing, but ray tracing in it’s most basic form means to test visibility between two points, which is what ray casting also means from time to time.