How to delete a transition from the transition table?

I've been merrily making states and actions and having a good time. Today though, i needed to delete a transition from the transition table, and whenever I click the minus icon on the table inspector/table editor, i get a bunch of NullReference exceptions while the table inspector disappears out of focus. Is this a bug? or is deletion of transitions still pending functionality?

 

On any particular state? Or one that you made?
I just tried and it works fine for me. Are conditions null in your case? (maybe that's the key? would be weird though)
Maybe you can post a photo of how the transition table looks like.

 

Then I'm doing something wrong, could you post a gif showing how you delete transitions please? Here's the transition table in the Inspector and in the Table Editor:

 

It's really not anything different, from your screenshot I would just press the (-) button next to the wrench in the "To Sailing" transition, and it would be gone.
What's the error you get in the console?

 

It's a cascade of errors, brace yourself.
First Error:
"
Retrieving array element that was out of bounds
UnityEditor.SerializedProperty:get_objectReferenceValue()
UOP1.StateMachine.Editor.TransitionTableEditor:RemoveTransition(SerializedTransition) (at Assets/Scripts/StateMachine/Editor/TransitionTableEditor.cs:310)
UOP1.StateMachine.Editor.TransitionDisplayHelperisplay(Rect&) (at Assets/Scripts/StateMachine/Editor/Utilities/TransitionDisplayHelper.cs:69)
UOP1.StateMachine.Editor.TransitionTableEditor:TransitionTableGUI() (at Assets/Scripts/StateMachine/Editor/TransitionTableEditor.cs:181)
UOP1.StateMachine.Editor.TransitionTableEditor:OnInspectorGUI() (at Assets/Scripts/StateMachine/Editor/TransitionTableEditor.cs:59)
UnityEngine.GUIUtilityrocessEvent(Int32, IntPtr)"

Second Error:
"
SerializedProperty _transitions.Array.data[36].FromState has disappeared!
UnityEditor.SerializedProperty:get_objectReferenceValue()
UOP1.StateMachine.Editor.TransitionTableEditor:RemoveTransition(SerializedTransition) (at Assets/Scripts/StateMachine/Editor/TransitionTableEditor.cs:310)
UOP1.StateMachine.Editor.TransitionDisplayHelperisplay(Rect&) (at Assets/Scripts/StateMachine/Editor/Utilities/TransitionDisplayHelper.cs:69)
UOP1.StateMachine.Editor.TransitionTableEditor:TransitionTableGUI() (at Assets/Scripts/StateMachine/Editor/TransitionTableEditor.cs:181)
UOP1.StateMachine.Editor.TransitionTableEditor:OnInspectorGUI() (at Assets/Scripts/StateMachine/Editor/TransitionTableEditor.cs:59)
UnityEngine.GUIUtilityrocessEvent(Int32, IntPtr)"

Third Error:
"
type is not a supported pptr value
UnityEditor.SerializedProperty:get_objectReferenceValue()
UOP1.StateMachine.Editor.TransitionTableEditor:RemoveTransition(SerializedTransition) (at Assets/Scripts/StateMachine/Editor/TransitionTableEditor.cs:310)
UOP1.StateMachine.Editor.TransitionDisplayHelperisplay(Rect&) (at Assets/Scripts/StateMachine/Editor/Utilities/TransitionDisplayHelper.cs:69)
UOP1.StateMachine.Editor.TransitionTableEditor:TransitionTableGUI() (at Assets/Scripts/StateMachine/Editor/TransitionTableEditor.cs:181)
UOP1.StateMachine.Editor.TransitionTableEditor:OnInspectorGUI() (at Assets/Scripts/StateMachine/Editor/TransitionTableEditor.cs:59)
UnityEngine.GUIUtilityrocessEvent(Int32, IntPtr)
"

Fourth Error:
"
NullReferenceException: Object reference not set to an instance of an object
UOP1.StateMachine.Editor.TransitionTableEditor.RemoveTransition (UOP1.StateMachine.Editor.SerializedTransition serializedTransition) (at Assets/Scripts/StateMachine/Editor/TransitionTableEditor.cs:310)
UOP1.StateMachine.Editor.TransitionDisplayHelper.Display (UnityEngine.Rect& position) (at Assets/Scripts/StateMachine/Editor/Utilities/TransitionDisplayHelper.cs:69)
UOP1.StateMachine.Editor.TransitionTableEditor.TransitionTableGUI () (at Assets/Scripts/StateMachine/Editor/TransitionTableEditor.cs:181)
UOP1.StateMachine.Editor.TransitionTableEditor.OnInspectorGUI () (at Assets/Scripts/StateMachine/Editor/TransitionTableEditor.cs:59)
UnityEditor.UIElements.InspectorElement+<>c__DisplayClass58_0.<CreateIMGUIInspectorFromEditor>b__0 () (at <8d21067e8d9c494db25a2b2485216e63>:0)
UnityEngine.GUIUtilityrocessEvent(Int32, IntPtr)
"

Fifth Error:
"
type is not a supported pptr value
UnityEditor.SerializedProperty:get_objectReferenceValue()
UOP1.StateMachine.Editor.TransitionTableEditor:TransitionTableGUI() (at Assets/Scripts/StateMachine/Editor/TransitionTableEditor.cs:105)
UOP1.StateMachine.Editor.TransitionTableEditor:OnInspectorGUI() (at Assets/Scripts/StateMachine/Editor/TransitionTableEditor.cs:59)
UnityEngine.GUIUtilityrocessEvent(Int32, IntPtr)
"

Sixth Error:
"
NullReferenceException: Object reference not set to an instance of an object
UOP1.StateMachine.Editor.TransitionTableEditor.TransitionTableGUI () (at Assets/Scripts/StateMachine/Editor/TransitionTableEditor.cs:105)
UOP1.StateMachine.Editor.TransitionTableEditor.OnInspectorGUI () (at Assets/Scripts/StateMachine/Editor/TransitionTableEditor.cs:59)
UnityEditor.UIElements.InspectorElement+<>c__DisplayClass58_0.<CreateIMGUIInspectorFromEditor>b__0 () (at <8d21067e8d9c494db25a2b2485216e63>:0)
UnityEngine.GUIUtilityrocessEvent(Int32, IntPtr)
"

 

Ignore the emojis, they are "colon [Some letter]" characters in the logs that the forum frontend formatted, not me.

 

I'm not too sure, as I didn't make the tool. @deivsky do you have any idea?

In any case, you could try debugging. Like, taking the first error, last function call, and see if in the place where the error occurs the data is how you expect it.

UOP1.StateMachine.Editor.TransitionTableEditor:RemoveTransition(SerializedTransition) (at Assets/Scripts/StateMachine/Editor/TransitionTableEditor.cs:310)

Check for instance if the name of the transition that's about to be deleted is correct, or the length of that array, etc.

 

Okay, I'll dive in during the weekend -foreseeing too much "life" for the rest of the week. Then I'll report on my findings. Cheers.

 

Always give "life" priority!

 

It turns out i just need to have another transition below the one i intend to delete. If you try to delete the current transition which also happens to be the "last" transition from that state, it blows up.
E.g. say you have two transitions from some 'Run' state. The first being 'Run' -> 'Jump', and below it you have 'Run' -> 'Attack' . If you tried to delete 'Run' -> 'Attack' (the second transition), then it blows up. Though, if you tried to delete 'Run' -> 'Jump', it deletes successfully. So just make sure that whichever transition you want to delete is NOT THE LAST transition from that state.

 

Thanks a lot for the investigation, @Arthur_Gentz! We will try to fix the tool as we can, but it's also useful to work around the issue for now. @Amel-Unity, you might find the above interesting!

Thanks again, Arthur!

 

I think I found the root of the problem -- the editor is trying to get the name of the transition's "From" state from an object that has already been deleted. That error cascades into a bunch of others. Simple fix is to grab that string before the deletion happens.

Take my patch for a spin and let me know if it's fixed for you? https://github.com/pointfivetee/open-project-1/tree/bugfix-delete-transition

(NB: If you have it open, you might need to close the transition table editor and then reopen it after the repo is updated.)

 

Nice! Can you open a PR for it? It's easier for us to try, and if it works, pull it in (and then you pop up as a collaborator too). Thanks!

 

Done: https://github.com/UnityTechnologies/open-project-1/pull/451
Created a git issue while I was at it: https://github.com/UnityTechnologies/open-project-1/issues/450