Default Editor : Enum as flags ?

Question

Hello there !

I juste have a little question regarding Unity default editor with enums. By default, when you declare an enum, it will create an editor when you can choose the enum value but you'll only be able to pick one of those.

Is there a way like an special attribute to tell Unity "this is a flag, enable me to pick as many values as I want" without writing a custom editor ?

Thanks in advance for your answers :)

Answer 1

Best Answer

Answer by froodydude · Aug 13, 2013 at 11:59 AM

This bugs me too but after some quick experimentation I think you can do it pretty trivially using the property drawer stuff. The main thing I noticed is to be aware of how Unity treats "Everything" as this sets all bits. I suspect it will also run in to problems if you leave gaps in your flags. I couldn't find a way to get the actual System.Type from the SerializedProperty, if it were possible to get this then you could make it more robust and also decide whether you want everything to mean set all bits or not. Anyway the code:

 public class EnumFlagsAttribute : PropertyAttribute
 {
     public EnumFlagsAttribute() { }
 }
 
 [CustomPropertyDrawer(typeof(EnumFlagsAttribute))]
 public class EnumFlagsAttributeDrawer : PropertyDrawer
 {
     public override void OnGUI(Rect _position, SerializedProperty _property, GUIContent _label)
     {
         _property.intValue = EditorGUI.MaskField( _position, _label, _property.intValue, _property.enumNames );
     }
 }

To use this you do the following:

 [System.Flags]
 public enum MyMaskedEnum
 {
     Flag0 = (1 << 0),
     Flag1 = (1 << 1),
     Flag2 = (1 << 2),
     Flag3 = (1 << 3),
 }
 
 class MyObject : MonoBehaviour
 {
     [SerializeField] [EnumFlagsAttribute] MyMaskedEnum m_flags;
 }

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s_guy · Oct 18, 2013 at 10:32 PM 2

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I like this! Probably worth mentioning that the attribute class must exist in a non-editor script and folder, and the property drawer class must exist in an editor script and folder. I had them in the same file as seems to be implied above. That tripped me up and it took some staring at the PropertyDrawer docs to figure it out.

For some reason the built-in "Everything" option is uncheckable for me. I use a custom definition for "All" in the enum, which is nice to have control over. I also like to define "None" in my enum as well as some combos that I use for mask testing, but don't intend for the field to be set to. Guess I'll mess with the editor UI a bit to see if I can suppress certain options.

UPDATE: found an alternative complete solution

http://answers.unity3d.com/questions/393992/custom-inspector-multi-select-enum-dropdown.html

yoyo · Jul 07, 2014 at 05:55 PM 0

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Note that this solution works if and only if your enum values are consecutive bits (1, 2, 4, 8, ...). If you have a 0 value ("None") or combined values, then EditorGUI.MaskField isn't sufficient.

For a complete solution, see the link mentioned in previous comment (http://answers.unity3d.com/questions/393992/custom-inspector-multi-select-enum-dropdown.html)

phort99 · Jun 23, 2016 at 12:52 AM 0

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Warning: The code in this answer isn't friendly to multiple-selection. As soon as you select two objects, the enum flags get overwritten without warning and with no way to undo. Here's my version of OnGUI that checks for changes before assigning. This is way safer.

     public override void OnGUI(Rect _position, UnityEditor.SerializedProperty _property, GUIContent _label)
     {
         // Change check is needed to prevent values being overwritten during multiple-selection
         UnityEditor.EditorGUI.BeginChangeCheck ();
         int newValue = UnityEditor.EditorGUI.MaskField( _position, _label, _property.intValue, _property.enumNames );
         if (UnityEditor.EditorGUI.EndChangeCheck ()) {
             _property.intValue = newValue;
         }
     }

laurentlavigne · Jul 01, 2016 at 05:14 AM 0

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Very elegant but doesn't handle multi selection. Add this right after OnGUI{

 EditorGUI.showMixedValue = _property.hasMultipleDifferentValues;

Answer 2

Answer by Democide · Feb 17, 2015 at 04:44 PM

I've also had this issue, and decided to build a different solution: Toggle Buttons.

alt text

It provides a better overview over the flags set but takes up more space in the Editor. You can check it out here:

http://www.sharkbombs.com/2015/02/17/unity-editor-enum-flags-as-toggle-buttons/

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chilly-15 · Oct 21, 2016 at 03:40 AM 0

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I made a few modifications to Martin's code (posted to comments of the link provided), which provide stacked buttons if you have a long list of flags in your enum.

![Stacked Toggle Buttons][1] [1]: /storage/temp/80586-screen-shot-2016-10-21-at-23229-pm.png

screen-shot-2016-10-21-at-23229-pm.png (15.4 kB)

Answer 3

Answer by TonyLi · Jul 04, 2013 at 08:41 PM

(( Doh, sorry, I have to apologize. I thought it did what I described below, but I forgot that I had written a custom inspector just to handle this one case. Never mind! :-) ))

You just need to use [System.Flags]. Unity will pick this up and treat the enum drop-down as a mask.

For example, in one of my projects, I defined a bit flag enum like this:

 [System.Flags]
 public enum QuestStatus {
     Unassigned = 0x1,
     Active = 0x2,
     Success = 0x4,
     Failure = 0x8
 }

Then I have a component similar to this:

 public class Quest : MonoBehaviour {
     QuestStatus questStatus;
 }

And the default inspector looks like the attached screenshot: alt text

enummask.png (8.0 kB)

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Em3rgency · Jul 04, 2013 at 08:49 PM 0

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Wait... Does this let you pick several at once?

TonyLi · Jul 05, 2013 at 02:33 AM 0

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Doh, sorry, I have to apologize. I thought it did, but I forgot that I had written a custom inspector just to handle this one case. Never mind! :-)

fafase · Nov 15, 2013 at 02:10 PM 0

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Old thread but well, this does allow you to get several at once, then you need a quick bit manipulation to figure out what is on.

 QuestStatus _status = QuestStatus.Active | QuestStatus.Success;

then you check what is on with:

 if((_status & QuestStatus.Active)==QuestStatus.Active)
     print("Active");
 else
     print("No active");

Ash-Blue · Dec 29, 2016 at 04:53 AM 0

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Please note that although this solution looks magical, it doesn't appear to be working in Unity 5.5+

TonyLi Ash-Blue · Dec 29, 2016 at 01:40 PM 1

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bunny83's answer below is a good solution. I think at the time I posted my response Unity Answers there wasn't a good way to retract/delete posts. I had forgotten that I'd written a custom inspector similar to bunny83's answer.

Answer 4

Answer by s_guy · Oct 19, 2013 at 02:05 AM

The answer posted by bunny83 solves this fully.

http://answers.unity3d.com/questions/393992/custom-inspector-multi-select-enum-dropdown.html

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Answer 5

Answer by Owen-Reynolds · Jul 04, 2013 at 03:46 PM

The official way (I think Unity does this for rigidbody constraints, and lots of traditional code uses hidden bitfields) is to set up the enum with all valid combinations, as bitfields. Suppose you want flags Airborne, Stunned and Dead:

 enum statusFlags { none, Airborne=1, Stunned=2, Dead=4,
                    AirStun=3, AirDead=5};
 // NOTE: Dead things can't be stunned

Then maybe something like:

 bool hasStatus(statusFlags current, statusflags checkAgainst) {
   int s1 = (int)current;
   return s1&((int)checkAgainst) == s1;
 }

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Default Editor : Enum as flags ?

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