From f0d413a2a77d66232ca7a0bd9fa5a080afb48af2 Mon Sep 17 00:00:00 2001
From: benrob0329 <ben@totallynotashadyweb.site>
Date: Tue, 4 Jan 2022 19:24:42 -0500
Subject: [PATCH] Document `vector` (#11)

---
 doc/classes/vector.adoc | 269 ++++++++++++++++++++++++++++++++++++++++
 include/config.adoc     |   2 +
 2 files changed, 271 insertions(+)
 create mode 100644 doc/classes/vector.adoc

diff --git a/doc/classes/vector.adoc b/doc/classes/vector.adoc
new file mode 100644
index 0000000..3ce471d
--- /dev/null
+++ b/doc/classes/vector.adoc
@@ -0,0 +1,269 @@
+= Vector API
+include::../../include/config.adoc[]
+:description: Documentation for the Vector class and API
+:keywords: mod, library, vector, x, y, z, pos, position
+
+TIP: The respective source code is located https://github.com/minetest/minetest/blob/master/builtin/common/vector.lua[here].
+
+== `vector` Namespace
+
+NOTE: The `vector` type used to be a simple `table` with `x`, `y`, and `z` values.
+However it has more recently been given metatable methods for convenience.
+Unless otherwise noted, the `vector` type always refers to the metatable-enhanced variety.
+Do note that functions here will accept an old-style (non-metatable) `vector`, but you cannot perform metatable operations with said `vector`.
+
+=== `vector.new(a, b, c) -> vector`
+* `a`: `number`, `vector`, or `nil`
+* `b`, `c`: `number` or `nil`
+
+If `a`, `b`, and `c` are `number`:: Returns a new `vector` where `{x = a, y = b, z = c}`
+
+NOTE: {deprecated}
+
+If `a` is a `vector`:: Returns `vector.copy(a)`
+If all parameters are `nil`:: Returns `vector.zero()`
+
+=== `vector.zero() -> vector`
+Returns a new `vector` where `{x = 0, y = 0, z = 0}`
+
+=== `vector.copy(v) -> vector`
+* `v`: `vector`
+
+Returns a new `vector` where `{x = v.x, y = v.y, z = v.z}`. This is *not* equivalent to `table.copy`, as that does not set the `vector` metatable.
+
+=== `vector.from_string(s, init) -> vector, number`
+* `s`: `string`
+* `init`: `number`
+
+Returns a new `vector` parsed from `s` using `string.match`, followed by the position of the first character following the parsed data.
+
+Expects `s` to be in the following format: `(x, y, z)` where `x`, `y`, and `z` are all valid numbers passed to `tonumber`.
+There are some allowances in the parsing rules for extra whitespace as padding around elements.
+You may set the position in `s` where `string.match` will begin parsing via `init`.
+
+=== `vector.to_string(v) -> string`
+* `v`: `vector`
+
+Returns a `string` representation of `v` in the format: `(v.x, v.y, v.z)`.
+
+Each component is formatted with the printf-style `%g` flag (either floating-point or scientific notation, whichever is shorter).
+
+=== `vector.equals(a, b) -> bool`
+* `a`, `b`: `vector`
+
+Returns `true` if `a` is equivalent to `b` (all components are the same).
+
+Returns `false` otherwise.
+
+=== `vector.length(v) -> number`
+* `v`: `vector`
+
+Returns the vectorial length (total traveled traveled distance from the origin to the end) of `v`.
+
+The formula for the length is: stem:[sqrt(x^2 + y^2 + z^2)].
+
+=== `vector.normalize(v) -> vector`
+* `v`: `vector`
+
+Returns a new `vector` which is the normalized form of `v` (the vectorial length is equal to 1).
+Uses `vector.length(v)` to get the vectorial length.
+
+Specifically, if the length is 0, returns a new `vector` with all components being `0`.
+Otherwise, returns `vector.divide(v, length)`.
+
+=== `vector.floor(v) -> vector`
+* `v`: `vector`
+
+Returns a new `vector` where each component of `v` has had `math.floor` applied to it.
+
+Literally `vector.apply(v, math.floor)`.
+
+=== `vector.round(v) -> vector`
+* `v`: `vector`
+
+Returns a new `vector` where each component of `v` has had `math.round` applied to it.
+
+Equivalent to `vector.apply(v, math.round)`
+
+=== `vector.apply(v, func) -> vector`
+* `v`: `vector`
+* `func`: `function`
+
+Returns a new `vector` where each component of `v` has had `func` applied to it.
+
+=== `vector.distance(a, b) -> number`
+* `a`, `b`: `vector`
+
+Returns a `number` which is equal to the distance between `a` and `b`.
+
+Distance is equal to the scalar (single number) result of stem:[|bar a - bar b|].
+
+=== `vector.direction(pos1, pos2) -> vector`
+* `pos1`, `pos2`: `vector`
+
+Returns a new, normalized `vector` equal to the direction from `pos1` to `pos2`.
+
+=== `vector.angle(a, b) -> number`
+* `a`, `b`: `vector`
+
+Returns a `number` which is equal to the angle (in radians) between `a` and `b`.
+
+Formula used is stem:[tan^-1(|bar a xx bar b|, bar a * bar b)].
+
+=== `vector.dot(a, b) -> number`
+* `a`, `b`: `vector`
+
+Returns a `number` equal to the dot product of `a` and `b`.
+
+=== `vector.cross(a, b) -> vector`
+* `a`, `b`: `vector`
+
+Returns a new `vector` which is equal to the cross product of `a` and `b`.
+
+=== `vector.add(a, b) -> vector`
+* `a`: `vector`
+* `b`: `vector` or `number`
+
+If `b` is a `vector`:: Returns a new `vector` where each component of `b` is added to each component of `a`
+If `b` is a `number`:: Returns a new `vector` where `b` is added to each component of `a`
+
+=== `vector.subtract(a, b) -> vector`
+* `a`: `vector`
+* `b`: `vector` or `number`
+
+If `b` is a `vector`:: Returns a new `vector` where each component of `b` is subtracted from each component of `a`
+If `b` is a `number`:: Returns a new `vector` where `b` is subtracted from each component of `a`
+
+=== `vector.multiply(a, b) -> vector`
+* `a`: `vector`
+* `b`: `vector` or `number`
+
+If `b` is a `vector`:: Returns a new `vector` where each component of `a` is multiplied by component of `b`
+If `b` is a `number`:: Returns a new `vector` where each component of `a` is multiplied by `b`
+
+=== `vector.divide(a, b) -> vector`
+* `a`: `vector`
+* `b`: `vector` or `number`
+
+If `b` is a `vector`:: Returns a new `vector` where each component of `a` is divided by component of `b`
+If `b` is a `number`:: Returns a new `vector` where each component of `a` is divided by `b`
+
+=== `vector.offset(v, x, y, z) -> vector`
+* `v`: `vector`
+* `x`, `y`, `z`: `number`
+
+Returns a new `vector` where each component of `x`, `y`, and `z` are added to the respective components of `v`.
+
+Equivalent to `vector.add(v, {x = x, y = y, z = z})`.
+
+=== `vector.sort(a, b) -> vector, vector`
+* `a`: `vector`
+* `b`: `vector`
+
+Returns two new `vector` values.
+
+The first consists of the smaller components of `a` and `b`, where each is equal to `math.min(a.N, b.N)` (N being one of x, y, or z).
+
+The second is similar to the first, but consisting of the larger components instead.
+
+=== `vector.check(v) -> bool`
+* `v`: `vector`
+
+Returns `true` if `v` is a valid, metatable-enhanced vector.
+
+Returns `false` otherwise.
+
+=== `vector.rotate_around_axis(v, axis, angle) -> vector`
+* `v`, `axis`: `vector`
+* `angle`: `number`
+
+Returns a new `vector` which is equal to `v` rotated around `axis` by `angle` radians counter-clockwise.
+
+=== `vector.rotate(v, rot) -> vector`
+* `v`, `rot`: `vector`
+
+Returns a new `vector` which is equal to `v` rotated by `rot` counter-clockwise.
+
+The way that the components of `rot` map is as follows:
+
+* `rot.x` is pitch
+* `rot.y` is yaw
+* `rot.z` is roll
+
+=== `vector.dir_to_rotation(forward, up) -> vector`
+* `forward`: `vector`
+* `up`: `vector` or `nil`
+
+Returns a new rotational `vector` (the same kind as `rot` in `vector.rotate`) equal to the rotation from `up` to `forward`.
+
+If `up` is `nil` then the returned rotational `vector` assumed that `y = 1` is up.
+
+Both `up` and `forward` are normalized by the function before calculations are made with them, so a call with or without normalization by the caller will be the same.
+
+== Metatable Functions
+
+Metatable-enhanced `vector` values have some convenience features to help make vector math more readable.
+They can have be used with normal math operations rather than needing to call the equivalent namespaced function.
+They also can be indexed either with named keys (`v.x` and `v["x"]`) or they can be indexed with numeric keys (`v[1]` being `v.x`, `v[2]` being `v.y`, and `v[3]` being `v.z`).
+
+.Using Metatable `vectors`
+====
+
+[source, lua]
+----
+local v1 = vector.new(1, 2, 3)
+local v2 = vector.new(4, 5, 6)
+local v3
+
+-- This:
+v3 = vector.add(v1, v2)
+-- Is equivalent to:
+v3 = v1 + v2
+
+-- You can also use do more lengthy calculations:
+v3 = ((v1 + v2) / 2) * 3
+-- The equivalent using the namespaced functions would be rather unwieldy:
+v3 = vector.multiply(vector.divide(vector.add(v1, v2), 2), 3)
+----
+
+====
+
+=== `metatable.__eq(a, b) -> bool`
+* `a`, `b`: `vector`
+
+Literally `vector.equals(a, b)`.
+
+=== `metatable.__unm(v) -> vector`
+* `v`: `vector`
+
+Returns a new `vector` which is the inverse of `v`.
+
+=== `metatable.__add(a, b) -> vector`
+* `a`, `b`: `vector`
+
+Returns a new `vector` where each component of `a` is added to each respective component of `b`.
+
+NOTE: Unlike `vector.add()` this does not support adding `number` values.
+
+=== `metatable.__sub(a, b) -> vector`
+* `a`, `b`: `vector`
+
+Returns a new `vector` where each component of `a` is subtracted from each respective component of `b`.
+
+NOTE: Unlike `vector.subtract()` this does not support subtracting `number` values.
+
+=== `metatable.__mul(a, b) -> vector`
+* `a`: `vector` or `number`
+* `b`: `number` or `vector`
+
+Returns a new `vector` where each component of `a` is multiplied by each respective component of `b`. Because of the way metatables work, either argument can be a `number` or a `vector` without any practical difference.
+
+CAUTION: This function assumes that one just one argument is a number, and will probably return confusing errors about "accessing a `nil` value" if two `vector` arguments are passed to it.
+
+=== `metatable.__div(a, b) -> vector`
+* `a`: `vector`
+* `b`: `number`
+
+Returns a new `vector` where each component of `a` is divided by `b`.
+
+CAUTION: This function assumes `b` is a number, and will probably return confusing errors about "accessing a `nil` value" if it is not.
diff --git a/include/config.adoc b/include/config.adoc
index 6490f79..0710108 100644
--- a/include/config.adoc
+++ b/include/config.adoc
@@ -12,3 +12,5 @@ Minetest-Docs and contributors
 :url-docs-repo: https://github.com/minetest/minetest_docs
 :url-lua-api: https://github.com/minetest/minetest/blob/master/doc/lua_api.txt
 :url-reference-manual: https://www.lua.org/manual/5.1/manual.html
+
+:deprecated: The following call(s) are deprecated, please don't use them as they will be removed in a future version of the engine.
\ No newline at end of file