better Vector3 coercion semantics

data/scripts/types/vector3.lua

@@ -27,6 +27,25 @@ local function is_weak_vector3(t)
   end
 end
 
+---Coerces t to a Vector3. If t is already a Vector3, returns it without copying.
+---@param t vectorlike
+---@param do_err boolean?
+---@param def Vector3?
+---@return boolean error, Vector3 result
+local function coerce(t, do_err, def)
+  do_err = do_err or true
+  if do_err and not is_weak_vector3(t) then
+    def = def or Vector3()
+    error("Vector3: can not coerce t into Vector3. Returning " .. tostring(def))
+    return true, def
+  end
+  if t["_CLASS_"] == "Vector3" then
+    return false, t
+  end
+
+  return false, Vector3(t)
+end
+
 ---Returns a Vector3 multiplied either component-wise (if b is a weak Vector3) or multiplies each component by b if b is a number.
 ---@param b number|vectorlike
 ---@return Vector3
@@ -167,12 +186,11 @@ end
 ---@param with vectorlike
 ---@return number
 function Vector3:dot(with)
-  if not is_weak_vector3(with) then
-    error("Vector3: with must be a Vector3-like table. Returning 0")
-    return 0
+  local err, v2 = coerce(with)
+  if err then
+    return 0.0
   end
 
-  local v2 = Vector3(with)
   return self.x * v2.x + self.y * v2.y + self.z * v2.z
 end
 
@@ -180,11 +198,10 @@ end
 ---@param with vectorlike
 ---@return Vector3
 function Vector3:cross(with)
-  if not is_weak_vector3(with) then
-    error("Vector3: with must be a Vector3-like table. Returning Vector3()")
-    return Vector3()
+  local err, v2 = coerce(with)
+  if err then
+    return v2
   end
-  local v2 = Vector3(with)
   return Vector3 {
     self.y * v2.z - self.z * v2.y,
     self.z * v2.x - self.x * v2.z,
@@ -197,17 +214,22 @@ end
 ---@param angle number
 ---@return Vector3
 function Vector3:rotated(axis, angle)
-  if not is_weak_vector3(axis) then
-    error("Vector3: axis must be a Vector3-like table. Returning Vector3()")
-    return Vector3()
+  -- if not is_weak_vector3(axis) then
+  --   error("Vector3: axis must be a Vector3-like table. Returning Vector3()")
+  --   return Vector3()
+  -- end
+  local err, vaxis = coerce(axis)
+  if err then
+    return vaxis
   end
 
-  axis = Vector3(axis):normalized()
+---@diagnostic disable-next-line: undefined-field
+  vaxis = vaxis:normalized()
   local cosa = math.cos(angle)
   local sina = math.sin(angle)
   -- __mul is only defined for the left operand (table), numbers don't get metatables.
   -- as such, the ordering of operations here is specific
-  local v = (self * cosa) + (axis * ((1 - cosa) * self:dot(axis))) + (axis:cross(self) * sina)
+  local v = (self * cosa) + (vaxis * ((1 - cosa) * self:dot(vaxis))) + (vaxis:cross(self) * sina)
   return Vector3(v)
 end
 
@@ -222,12 +244,11 @@ end
 ---@param t number
 ---@return Vector3
 function Vector3:lerp(b, t)
-  -- return self:copy()
-  if not is_weak_vector3(b) then
-    error("Vector3: b must be a Vector3-like table. Returning copy of self.")
-    return self:copy()
+  local err, w = coerce(b)
+  if err then
+    return w
   end
-  local w = Vector3(b)
+
   return Vector3{
     util.lerp(self.x, w.x, t),
     util.lerp(self.y, w.y, t),
@@ -235,6 +256,44 @@ function Vector3:lerp(b, t)
   }
 end
 
+function Vector3:direction_to(to)
+  local err, other = coerce(to)
+  if err then
+    return 0.0
+  end
+
+  return Vector3(other.x - self.x, other.y - self.y, other.z - self.z):normalized()
+end
+
+---Returns the squared distance between this vector and to.
+---@param to vectorlike
+---@return number
+function Vector3:distance_squared_to(to)
+  local err, other = coerce(to)
+  if err then
+    return 0.0
+  end
+
+  return (other - self):length_squared()
+end
+
+---Returns the distance between this vector and to.
+---@param to vectorlike
+---@return number
+function Vector3:distance_to(to)
+  local err, other = coerce(to)
+  if err then
+    return 0.0
+  end
+
+  return (other - self):length()
+end
+
+---Returns a new vector with the Y discarded (0).
+---@return Vector3
+function Vector3:horizontal()
+  return Vector3(self.x, 0.0, self.z)
+end
 ---- CONSTANTS
 
 Vector3.UP = Vector3(0, 1, 0)