feat(actors): add an invisible wall object

sonic-radiance.love/game/modules/world/actors/init.lua

@@ -8,6 +8,7 @@ Obj.index     = {}
 Obj.index["player"]   = Obj.Player
 
 Obj.collisions = {}
-Obj.collisions["wall"] = require(cwd .. "wall")
+Obj.collisions["wall"]      = require(cwd .. "wall")
+Obj.collisions["invisible"] = require(cwd .. "invisible")
 
 return Obj

sonic-radiance.love/game/modules/world/actors/invisible.lua

@@ -0,0 +1,13 @@
+local Base = require "core.modules.world.actors.actor3D"
+local Invisible = Base:extend()
+
+function Invisible:new(world, x, y, z, w, h, d)
+  Invisible.super.new(self, world, "wall", x, y, z, w, h, d, true)
+  self:setDebugColor(0,0,0)
+end
+
+function Invisible:update(dt)
+
+end
+
+return Invisible