feat(relativeCoords): add lib.getRelativeCoords function (#685)

imports/getRelativeCoords/shared.lua

@@ -0,0 +1,30 @@
+local glm_sincos = require 'glm'.sincos
+local glm_rad = require 'glm'.rad
+
+---Get the relative coordinates of a vector3 based on a heading and offset
+---@overload fun(coords: vector3, heading: number, offset: vector3): vector3
+---@overload fun(coords: vector4, offset: vector3): vector4
+---@param coords vector3 | vector4
+---@param heading number
+---@param offset vector3
+---@return vector3
+function lib.getRelativeCoords(coords, heading, offset)
+    offset = offset or heading
+    local x, y, z, w = coords.x, coords.y, coords.z, type(heading) == 'number' and heading or coords.w
+    local sin, cos = glm_sincos --[[@as fun(n: number): number, number]](glm_rad(w))
+    local relativeX = offset.x * cos - offset.y * sin
+    local relativeY = offset.x * sin + offset.y * cos
+
+    return coords.w and vec4(
+        x + relativeX,
+        y + relativeY,
+        z + offset.z,
+        w
+    ) or vec3(
+        x + relativeX,
+        y + relativeY,
+        z + offset.z
+    )
+end
+
+return lib.getRelativeCoords