Question Can I reference a float..?

I want to populate a drop-down with all the floats from a component. I would then like to reference the selected float. What can I do?

 

You can use Reflection to do runtime introspection of variables, methods, properties, etc.

This is usually a last resort method and not at all a trivial or good thing to implement.

This sounds like and XY Problem that could probably be solved another way.

https://en.wikipedia.org/wiki/XY_problem

 

I was afraid of that.

Probably.

I wanted to make a slider where I could reference a component and pick from the component which float I wanted to use to be the sliders value. That way I won't have to keep writing scripts to set the value of sliders.

 

Is reflection really the best option for what I'm trying to do here? I've never used reflection, and it sounds like it will be slow if I have to do it alot/every frame..

 

Lots of nice data-bindy ways to handle this without going to reflection.

My Datasacks package uses this to bind a Datasack (a ScriptableObject) to UI items, such as a Slider.

You can look at it and use it as-is, or just model a much simpler single-purpose stripped down version if you prefer.



Datasacks is presently hosted at these locations:

https://bitbucket.org/kurtdekker/datasacks

https://github.com/kurtdekker/datasacks

https://gitlab.com/kurtdekker/datasacks

https://sourceforge.net/projects/datasacks/

 

This is something UI Elements (Unity's new UI) has native support for. It's called Bindings, and allows you to bind public properties together.

 

I don't think this will work for runtime ui though

 

Is it necessary to support more than a known set of components?

 

I'm trying to understand the examples from the repo but I think i'm too dumb to understand how to use this package...

Edit: Had to sleep on it. I think I'm understanding it better and this seems pretty neat. I think what would make Datasacks appeal to me more would be the ability to store any value from any component into a sack with no code.

I'm gonna try, ty.

 

I'm sorry I'm not sure what you're asking

 

No. You answered my question with that second sentence.

Edit: Here is a basic implementation. The data in the list is stored as a tuple if you haven't seen it before.

https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/builtin-types/value-tuples

Code (csharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using System.Reflection;
4. using UnityEngine;
5.  
6. public class Foo : MonoBehaviour
7. {
8.     public void Start()
9.     {
10.         foreach ((string, float) entry in GetObjectFloats(GetComponent<Rigidbody>()))
11.         {
12.             Debug.Log($"Name: {entry.Item1}, Value: {entry.Item2}");
13.         }
14.     }
15.  
16.     public List<(string, float)> GetObjectFloats(Object obj)
17.     {
18.         List<(string, float)> entries = new List<(string, float)>();
19.         BindingFlags flags = BindingFlags.Public | BindingFlags.Instance;
20.  
21.         FieldInfo[] fields = obj.GetType().GetFields(flags);
22.         foreach (FieldInfo fieldInfo in fields)
23.             if (fieldInfo.FieldType == typeof(float))
24.             {
25.                 //Debug.Log($"Obj: {obj.name}, Fields: {fieldInfo.Name}, Value: {fieldInfo.GetValue(obj)}");
26.                 entries.Add((fieldInfo.Name, (float)fieldInfo.GetValue(obj)));
27.             }
28.  
29.         PropertyInfo[] properties = obj.GetType().GetProperties(flags);
30.         foreach (PropertyInfo propertyInfo in properties)
31.             if (propertyInfo.PropertyType == typeof(float))
32.             {
33.                 //Debug.Log($"Obj: {obj.name}, Fields: {propertyInfo.Name}, Value: {propertyInfo.GetValue(obj)}");
34.                 entries.Add((propertyInfo.Name, (float)propertyInfo.GetValue(obj)));
35.             }
36.  
37.         return entries;
38.     }
39. }

 

If you don't want to use reflection, then you could combine a Model(Basic Class or Scriptable Object)/JSON approach.

Use Newtonsoft to convert your object to a JObject, and get all properties where the type is number.
Then use that list to populate dropdown names. And get/set methods to get or update values.

On the Set method, update the components object.

---

Note: On a low level, this probably does similar to reflection, so I'm not sure if it will have any better performance.
And both can be written in similar amounts of code.

 

Thanks everyone. Here's what I got:

Code (CSharp):

1. using System;
2. using System.Collections.Generic;
3. using System.Reflection;
4. using UnityEngine;
5. using UnityEngine.UI;
6.  
7. public class SliderExtended : Slider {
8.  
9.     [Tooltip("Inserting a component into this slot allows you to pick a float from the component to be used as the slider value.")]
10.     public Component valueOverride;
11.     [HideInInspector]
12.     public int selectedEntry;
13.     public List<(string, float)> entries;
14.  
15.     public void Update() {
16.         base.Update();
17.         if (valueOverride) {
18.             GetObjectFloats(valueOverride);
19.             if (entries.Count > 0) {
20.                 value = entries[selectedEntry].Item2;
21.             }
22.         }
23.     }
24.  
25.     public List<(string, float)> GetObjectFloats(UnityEngine.Object obj) {
26.         entries = new List<(string, float)>();
27.         BindingFlags flags = BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.Default | BindingFlags.DeclaredOnly;
28.         FieldInfo[] fields = obj.GetType().GetFields(flags);
29.         foreach (FieldInfo fieldInfo in fields)
30.             if (fieldInfo.FieldType == typeof(float)) {
31.                 entries.Add((fieldInfo.Name, (float)fieldInfo.GetValue(obj)));
32.             }
33.         PropertyInfo[] properties = obj.GetType().GetProperties(flags);
34.         foreach (PropertyInfo propertyInfo in properties)
35.             if (propertyInfo.PropertyType == typeof(float)) {
36.                 entries.Add((propertyInfo.Name, (float)propertyInfo.GetValue(obj)));
37.             }
38.         return entries;
39.     }
40.  
41.     public string[] GetListStringFromObj(UnityEngine.Object obj) {
42.         List<String> result = new List<string>();
43.         GetObjectFloats(obj);
44.         for (int i = 0; i < entries.Count; i++) {
45.             result.Add(entries[i].Item1);
46.         }
47.         return result.ToArray();
48.     }
49. }
50.  

Editor script

Code (CSharp):

1. using UnityEditor;
2. using UnityEngine;
3.  
4. [CustomEditor(typeof(SliderExtended))]
5. public class SliderExtendedEditor : Editor {
6.  
7.     public override void OnInspectorGUI() {
8.         // Show default inspector property editor
9.         DrawDefaultInspector();
10.         GUIStyle style = new GUIStyle(GUI.skin.GetStyle("label")) {
11.             wordWrap = true
12.         };
13.         EditorGUILayout.LabelField("Checks component for values that can override slider value. Leave blank to disable.", style);
14.         SliderExtended sliderExtended = target as SliderExtended;
15.         //Popup
16.         if (sliderExtended && sliderExtended.valueOverride && !Application.isPlaying) {
17.             string[] options = sliderExtended.GetListStringFromObj(sliderExtended.valueOverride);
18.             int index = EditorGUILayout.Popup("Available Values (float)", sliderExtended.selectedEntry, options);
19.             sliderExtended.selectedEntry = index;
20.         }
21.     }
22. }
23.