Fix GetAngleInBetween refactor (#6525)

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Co-authored-by: lL1l1 <[email protected]>

changelog/snippets/other.6438.md

@@ -1,4 +1,4 @@
-- (#5061, #6438, #6527) Add metamethods and utility functions for Vectors and Quaternions to simplify and clean up the code involving operations with them.
+- (#5061, #6438, #6527, #6525) Add metamethods and utility functions for Vectors and Quaternions to simplify and clean up the code involving operations with them.
   - This **removes** the file `/lua/shared/quaternions.lua`, which was added in #4768 (Mar 4, 2023), so mods that use that file will have to be updated.
   - The metamethods (defined globally in `/lua/system/utils.lua`) include:
     - Vector/Vector2 addition/subtraction/negation

lua/utilities.lua

@@ -406,12 +406,11 @@ end
 ---@param v2 Vector
 ---@return number
 function GetAngleInBetween(v1, v2)
-    local x1, y1, z2 = v1[1], v1[2], v1[3]
+    local x1, y1, z1 = v1[1], v1[2], v1[3]
     local x2, y2, z2 = v2[1], v2[2], v2[3]
     -- arccos((v1 . v2) / (|v1| |v2|))
-    local z2Sq = z2 * z2
-    local dot = x1*x2 + y1*y2 + z2Sq
-    local len2 = MathSqrt((x1*x1 + y1*y1 + z2Sq) * (x2*x2 + y2*y2 + z2Sq))
+    local dot = x1 * x2 + y1 * y2 + z1 * z2
+    local len2 = MathSqrt((x1 * x1 + y1 * y1 + z1 * z1) * (x2 * x2 + y2 * y2 + z2 * z2))
     return MathACos(dot / len2) * 180 / math.pi
 end