Why can't we reference TextMeshProUGUI inside IComponentData?

At the moment it is unfortunately impossible to reference TextMeshProUGUI inside an IComponentData class.

At build time it throws this error:

Code (CSharp):

1. Something went wrong while Post Processing the assembly (Main.dll) :
2. Member 'UnityEngine.TextCore.Glyph' is declared in another module and needs to be imported
3.   at Mono.Cecil.MetadataBuilder.LookupToken (Mono.Cecil.IMetadataTokenProvider provider) [0x0003c] in <58b86858c52b4b5fbb6efedd16c9c16a>:0
4.   at Mono.Cecil.SignatureWriter.MakeTypeDefOrRefCodedRID (Mono.Cecil.TypeReference type) [0x00000] in <58b86858c52b4b5fbb6efedd16c9c16a>:0
5.   at Mono.Cecil.SignatureWriter.WriteTypeSignature (Mono.Cecil.TypeReference type) [0x00161] in <58b86858c52b4b5fbb6efedd16c9c16a>:0
6.   at Mono.Cecil.SignatureWriter.WriteGenericInstanceSignature (Mono.Cecil.IGenericInstance instance) [0x00021] in <58b86858c52b4b5fbb6efedd16c9c16a>:0
7.   at Mono.Cecil.SignatureWriter.WriteTypeSignature (Mono.Cecil.TypeReference type) [0x000cf] in <58b86858c52b4b5fbb6efedd16c9c16a>:0
8.   at Mono.Cecil.SignatureWriter.WriteGenericInstanceSignature (Mono.Cecil.IGenericInstance instance) [0x00021] in <58b86858c52b4b5fbb6efedd16c9c16a>:0
9.   at Mono.Cecil.MetadataBuilder.GetMethodSpecSignature (Mono.Cecil.MethodSpecification method_spec) [0x00023] in <58b86858c52b4b5fbb6efedd16c9c16a>:0
10.   at Mono.Cecil.MetadataBuilder.CreateMethodSpecRow (Mono.Cecil.MethodSpecification method_spec) [0x00012] in <58b86858c52b4b5fbb6efedd16c9c16a>:0
11.   at Mono.Cecil.MetadataBuilder.GetMethodSpecToken (Mono.Cecil.MethodSpecification method_spec) [0x00000] in <58b86858c52b4b5fbb6efedd16c9c16a>:0
12.   at Mono.Cecil.MetadataBuilder.LookupToken (Mono.Cecil.IMetadataTokenProvider provider) [0x000cb] in <58b86858c52b4b5fbb6efedd16c9c16a>:0
13.   at Mono.Cecil.Cil.CodeWriter.WriteOperand (Mono.Cecil.Cil.Instruction instruction) [0x00229] in <58b86858c52b4b5fbb6efedd16c9c16a>:0
14.   at Mono.Cecil.Cil.CodeWriter.WriteInstructions () [0x0002c] in <58b86858c52b4b5fbb6efedd16c9c16a>:0
15.   at Mono.Cecil.Cil.CodeWriter.WriteResolvedMethodBody (Mono.Cecil.MethodDefinition method) [0x0002e] in <58b86858c52b4b5fbb6efedd16c9c16a>:0
16.   at Mono.Cecil.Cil.CodeWriter.WriteMethodBody (Mono.Cecil.MethodDefinition method) [0x0002b] in <58b86858c52b4b5fbb6efedd16c9c16a>:0
17.   at Mono.Cecil.MetadataBuilder.AddMethod (Mono.Cecil.MethodDefinition method) [0x00013] in <58b86858c52b4b5fbb6efedd16c9c16a>:0
18.   at Mono.Cecil.MetadataBuilder.AddMethods (Mono.Cecil.TypeDefinition type) [0x00013] in <58b86858c52b4b5fbb6efedd16c9c16a>:0
19.   at Mono.Cecil.MetadataBuilder.AddType (Mono.Cecil.TypeDefinition type) [0x000a2] in <58b86858c52b4b5fbb6efedd16c9c16a>:0
20.   at Mono.Cecil.MetadataBuilder.AddTypes () [0x00018] in <58b86858c52b4b5fbb6efedd16c9c16a>:0
21.   at Mono.Cecil.MetadataBuilder.BuildTypes () [0x00014] in <58b86858c52b4b5fbb6efedd16c9c16a>:0
22.   at Mono.Cecil.MetadataBuilder.BuildModule () [0x0009f] in <58b86858c52b4b5fbb6efedd16c9c16a>:0
23.   at Mono.Cecil.MetadataBuilder.BuildMetadata () [0x00000] in <58b86858c52b4b5fbb6efedd16c9c16a>:0
24.   at Mono.Cecil.ModuleWriter+<>c.<BuildMetadata>b__2_0 (Mono.Cecil.MetadataBuilder builder, Mono.Cecil.MetadataReader _) [0x00000] in <58b86858c52b4b5fbb6efedd16c9c16a>:0
25.   at Mono.Cecil.ModuleDefinition.Read[TItem,TRet] (TItem item, System.Func`3[T1,T2,TResult] read) [0x00025] in <58b86858c52b4b5fbb6efedd16c9c16a>:0
26.   at Mono.Cecil.ModuleWriter.BuildMetadata (Mono.Cecil.ModuleDefinition module, Mono.Cecil.MetadataBuilder metadata) [0x0000f] in <58b86858c52b4b5fbb6efedd16c9c16a>:0
27.   at Mono.Cecil.ModuleWriter.Write (Mono.Cecil.ModuleDefinition module, Mono.Disposable`1[T] stream, Mono.Cecil.WriterParameters parameters) [0x000fb] in <58b86858c52b4b5fbb6efedd16c9c16a>:0
28.   at Mono.Cecil.ModuleWriter.WriteModule (Mono.Cecil.ModuleDefinition module, Mono.Disposable`1[T] stream, Mono.Cecil.WriterParameters parameters) [0x00002] in <58b86858c52b4b5fbb6efedd16c9c16a>:0
29.   at Mono.Cecil.ModuleDefinition.Write (System.IO.Stream stream, Mono.Cecil.WriterParameters parameters) [0x00019] in <58b86858c52b4b5fbb6efedd16c9c16a>:0
30.   at Mono.Cecil.AssemblyDefinition.Write (System.IO.Stream stream, Mono.Cecil.WriterParameters parameters) [0x00000] in <58b86858c52b4b5fbb6efedd16c9c16a>:0
31.   at Unity.Entities.CodeGen.EntitiesILPostProcessors.Process (Unity.CompilationPipeline.Common.ILPostProcessing.ICompiledAssembly compiledAssembly) [0x000df] in C:\Plastic\2019_kona2\Library\PackageCache\com.unity.entities@0.6.0-preview.24\Unity.Entities.CodeGen\EntitiesILPostProcessor.cs:58
32.   at UnityEditor.Scripting.ScriptCompilation.ILPostProcessing.RunILPostProcessors (UnityEditor.Scripting.ScriptCompilation.ScriptAssembly assembly, System.String outputTempPath) [0x0011b] in <c10752821eec4acbb89ccd53fbbc5e27>:0
33.   at UnityEditor.Scripting.ScriptCompilation.ILPostProcessing.PostProcess (UnityEditor.Scripting.ScriptCompilation.ScriptAssembly assembly, System.Collections.Generic.List`1[T] messages, System.String outputTempPath) [0x00061] in <c10752821eec4acbb89ccd53fbbc5e27>:0
34.  

Is there any reason for this?

The workaround is to store it in a Monobehaviour and add it on an entity through AddComponentObject. This is not very convenient.

 

IComponentData cannot contain any managed references. The MonoBehaviour/AddComponentObject workaround you describe is the only way to do it for the time being.

 

That is not true, a IComponentData class can hold managed references.

 

i think thats only while running on the main thread and without burst.. no?

 

Of course, anything "Ui" at the moment can't run anywhere else anyway.

 

i have the same problem, were you able to fix this ? or you stick with AddComponentObject way ?

 

What I do for UI is that I have one IComponentData struct that is just a tag, and a ComponentObject that is a Monobehaviour referencing every MonoBehaviour or ScriptableObject that I need in a specific context.

This way all ECS systems requiring just some data can do it in burst and jobs, but UI-specific things are running in non-burst on the main thread.

The advantage of this is as some components become available in ECS, I just have to move them to the struct until all are gone.

Ex:

Code (CSharp):

1. using TMPro;
2. using UnityEngine;
3. using UnityEngine.UI;
4. namespace Ui.Views.ItemInspector
5. {
6.      public class ItemInspectorViewObject : MonoBehaviour
7.      {
8.          public TextMeshProUGUI TitleText = null;
9.          public TextMeshProUGUI DescriptionText = null;
10.          public Image SpriteImage = null;
11.    
12.      }
13. }

Code (CSharp):

1. using Items.EquippedAnimation.InspectMode;
2. using Parabole.Ui.ViewSystem;
3. using Ui.ScriptableObjects;
4. using Unity.Entities;
5.  
6. namespace Ui.Views.ItemInspector
7. {
8.     [UpdateInGroup(typeof(InspectModeSystemGroup))]
9.     [UpdateAfter(typeof(TriggerInspectModeEquipSystem))]
10.     public class ItemInspectorViewShowSystem : SystemBase
11.     {
12.         private EntityQuery _viewQuery;
13.        
14.         protected override void OnCreate()
15.         {
16.             _viewQuery = GetEntityQuery(
17.                 ComponentType.ReadOnly<ItemInspectorView>(),
18.                 ComponentType.ReadOnly<ItemInspectorViewObject>(),
19.                 ComponentType.ReadOnly<ShowItemInspectorView>(),
20.                 ComponentType.Exclude<Visible>());
21.  
22.             RequireForUpdate(_viewQuery);
23.         }
24.  
25.         protected override void OnUpdate()
26.         {
27.             Entities
28.                 .WithAll<ItemInspectorView>()
29.                 .WithoutBurst()
30.                 .ForEach((ItemInspectorViewObject viewObj, in ShowItemInspectorView showItem) =>{
31.                     var uiData = EntityManager.GetComponentObject<ItemUiData>(showItem.ItemEntity);
32.                     viewObj.TitleText.SetText(uiData.Name);
33.                     viewObj.DescriptionText.SetText(uiData.Description);
34.                     viewObj.SpriteImage.sprite = uiData.Sprites.Sprite_64;})
35.                 .Run();
36.  
37.             EntityManager.AddComponent<Show>(_viewQuery);
38.         }
39.     }
40. }