Prevent cycles with ARC by adding {.cursor.} to all "back" references.

TODO: Use destructors to set all cursors of children objects to `nil`.

src/types.nim

@@ -98,7 +98,7 @@ type
     GameObject* = ref object of RootObj
         # TODO: remove otype
         otype*: ObjectType ## private
-        engine*: MyouEngine ## private
+        engine* {.cursor.}: MyouEngine ## private
         debug*: bool ## private
         position*: Vec3
         rotation*: Quat
@@ -110,12 +110,12 @@ type
         object_color*: Vec4
         # alpha*: float
         matrix_parent_inverse*: Mat4
-        scene*: Scene
+        scene* {.cursor.}: Scene
         source_scene_name*: string
         # data_dir*: string
         # dupli_group*: unknown
         visible*: bool
-        parent*: GameObject
+        parent* {.cursor.}: GameObject
         children*: seq[GameObject]
         auto_update_matrix*: bool
         world_matrix*: Mat4
@@ -158,7 +158,8 @@ type
     
     # most fields should be private
     MeshData* = ref object
-        engine*: MyouEngine
+        engine* {.cursor.}: MyouEngine
+        # TODO: seq of {.cursor.}s?
         users*: seq[GameObject] ## private
         hash*: string
         varrays*: seq[ArrRef[float32]]
@@ -287,8 +288,8 @@ type
     # shadows
 
     ShadowManager* = ref object of RootObj
-        engine*: MyouEngine
-        light*: Light
+        engine* {.cursor.}: MyouEngine
+        light* {.cursor.}: Light
         framebuffer*: Framebuffer
         texture*: Texture
         sampler_type*: string
@@ -330,7 +331,7 @@ type
         padding3: float32
         
     Scene* = ref object
-        engine*: MyouEngine
+        engine* {.cursor.}: MyouEngine
         name*: string
         enabled*: bool
         children*: seq[GameObject]
@@ -406,7 +407,7 @@ type
         viewport_size*, viewport_size_inv*: Vec2
 
     RenderManager* = ref object
-        engine*: MyouEngine
+        engine* {.cursor.}: MyouEngine
         initialized*: bool
         # temporary_framebuffers*: Table[int, ByteFramebuffer]
         render_tick*: int
@@ -492,7 +493,7 @@ type
     # ubo.nim
 
     UBO* = ref object
-        renderer*: RenderManager
+        renderer* {.cursor.}: RenderManager
         name*: string
         size32*: int
         byte_storage*: ArrRef[byte]
@@ -529,7 +530,7 @@ type
         EsPrecisionHigh
 
     Material* = ref object
-        engine*: MyouEngine
+        engine* {.cursor.}: MyouEngine
         name*: string
         textures*: OrderedTable[string, Texture]
         ubos*: seq[UBO]
@@ -560,7 +561,7 @@ type
     
     # TODO: choose better names
     Shader* = ref object
-        engine*: MyouEngine # do we need this?
+        engine* {.cursor.}: MyouEngine # do we need this?
         id*: int
         program*: GLuint
         material*: Material # do we need this?
@@ -639,7 +640,7 @@ type
         tile_size*: Vec2
 
     Texture* = ref object of RootObj
-        engine*: MyouEngine
+        engine* {.cursor.}: MyouEngine
         name*: string
         storage*: TextureStorage ## private
         loaded*: bool
@@ -660,7 +661,7 @@ type
         DepthTexture
     
     Framebuffer* = ref object of RootObj
-        engine*: MyouEngine
+        engine* {.cursor.}: MyouEngine
         width*, height*: int
         format*: TextureFormat
         depth_type*: FramebufferDepthType
@@ -752,7 +753,7 @@ type
     # loader_base.nim
 
     Loader* = ref object of RootObj
-        engine*: MyouEngine
+        engine* {.cursor.}: MyouEngine
         shader_library*: string
         shader_textures*: Table[string, Texture]
         # on_destroy*: OnDestroy
@@ -777,7 +778,7 @@ type
     Body* = ref object
 
     Screen* = ref object of RootObj
-        engine*: MyouEngine
+        engine* {.cursor.}: MyouEngine
         width*, height*: int32
         orientation*: int8
         viewports*: seq[Viewport]