Add `math.round` and fix `vector.round` (#10803)

.luacheckrc

@@ -20,7 +20,7 @@ read_globals = {
 
 	string = {fields = {"split", "trim"}},
 	table  = {fields = {"copy", "getn", "indexof", "insert_all"}},
-	math   = {fields = {"hypot"}},
+	math   = {fields = {"hypot", "round"}},
 }
 
 globals = {

builtin/common/misc_helpers.lua

@@ -244,6 +244,15 @@ function math.factorial(x)
 	return v
 end
 
+
+function math.round(x)
+	if x >= 0 then
+		return math.floor(x + 0.5)
+	end
+	return math.ceil(x - 0.5)
+end
+
+
 function core.formspec_escape(text)
 	if text ~= nil then
 		text = text:gsub("\\", "\\\\")

builtin/common/vector.lua

@@ -1,6 +1,6 @@
 vector = {}
 
-local floor, hypot = math.floor, math.hypot
+local floor, hypot, round = math.floor, math.hypot, math.round
 local min, max, pi = math.min, math.max, math.pi
 
 function vector.new(a, b, c)
@@ -43,9 +43,9 @@ end
 
 function vector.round(v)
 	return {
-		x = floor(v.x + 0.5),
-		y = floor(v.y + 0.5),
-		z = floor(v.z + 0.5)
+		x = round(v.x),
+		y = round(v.y),
+		z = round(v.z)
 	}
 end
 

doc/lua_api.txt

@@ -3164,6 +3164,7 @@ For the following functions, `v`, `v1`, `v2` are vectors,
     * Returns a vector, each dimension rounded down.
 * `vector.round(v)`:
     * Returns a vector, each dimension rounded to nearest integer.
+    * At a multiple of 0.5, rounds away from zero.
 * `vector.apply(v, func)`:
     * Returns a vector where the function `func` has been applied to each
       component.
@@ -3342,6 +3343,8 @@ Helper functions
     * If the absolute value of `x` is within the `tolerance` or `x` is NaN,
       `0` is returned.
 * `math.factorial(x)`: returns the factorial of `x`
+* `math.round(x)`: Returns `x` rounded to the nearest integer.
+    * At a multiple of 0.5, rounds away from zero.
 * `string.split(str, separator, include_empty, max_splits, sep_is_pattern)`
     * `separator`: string, default: `","`
     * `include_empty`: boolean, default: `false`