99% Pure ECS Camera System Example

Hi this is my pretty much pure ECS camera system. A Pure ECS entity is created with a camera component and has a child entity with spring arm component (Like Unreal so please don't hate on me )
The SpringArm entity's position is saved and sent to Camera.Main's position and Camera entity's rotation is saved and sent to Camera.Main's rotation.

Edit : Fixed wrong rotation being used

Authors

Code (CSharp):

1. [RequiresEntityConversion]
2. public class CameraAuthor : MonoBehaviour, IConvertGameObjectToEntity
3. {
4.     public void Convert(Entity entity, EntityManager entityManager, GameObjectConversionSystem conversionSystem)
5.     {
6.         entityManager.AddComponentData(entity, new CameraComponent());
7.     }
8. }
9.  
10. [RequiresEntityConversion]
11. public class CameraSpringArmAuthor : MonoBehaviour, IConvertGameObjectToEntity
12. {
13.     public void Convert(Entity entity, EntityManager entityManager, GameObjectConversionSystem conversionSystem)
14.     {
15.         entityManager.AddComponentData(entity, new CameraSpringArmComponent());
16.     }
17. }
18.  
19. [RequiresEntityConversion]
20. public class CameraTargetAuthor : MonoBehaviour, IConvertGameObjectToEntity
21. {
22.     public void Convert(Entity entity, EntityManager entityManager, GameObjectConversionSystem conversionSystem)
23.     {
24.         entityManager.AddComponentData(entity, new CameraTargetComponent());
25.     }
26. }

Components

Code (CSharp):

1. using Unity.Entities;
2.  
3. public struct CameraComponent: IComponentData
4. {
5.     byte vaule;
6. }
7.  
8. public struct CameraSpringArmComponent : IComponentData
9. {
10.     byte value;
11. }
12.  
13. public struct CameraTargetComponent : IComponentData
14. {
15.     byte value;
16. }

System

Code (CSharp):

1.  
2. using Unity.Entities;
3. using Unity.Transforms;
4. using Unity.Mathematics;
5. using Unity.Collections;
6. using UnityEngine;
7.  
8. [UpdateInGroup(typeof(PresentationSystemGroup))]
9. public class CaneraSystem : ComponentSystem
10. {
11. private EntityQuery cameraTargetEntityQuery;
12. private float3 cameraRenderTranslation;
13. private float3 cameraRenderRotation;
14.  
15. protected override void OnCreate()
16. {
17. cameraTargetEntityQuery = GetEntityQuery(ComponentType.ReadOnly<CameraTargetComponent>(),ComponentType.ReadOnly<LocalToWorld>());
18. }
19.  
20. protected override void OnUpdate()
21. {
22. var cameraTargetEntities = cameraTargetEntityQuery.ToEntityArray(Allocator.TempJob);
23.  
24. if (cameraTargetEntities.Length == 0)
25. return;
26.  
27. //Initalize Camera
28. Entities.WithNone(typeof(Parent)).ForEach((Entity entity, ref CameraComponent cameraComponent) =>
29. {
30. PostUpdateCommands.AddComponent(entity, new LocalToParent());
31. PostUpdateCommands.AddComponent(entity,new Parent {});
32. return;
33.  
34. });
35.  
36. //Update Spring Arm
37. Entities.ForEach((ref Translation translation, ref Rotation rotation, ref CameraSpringArmComponent cameraSpringArmComponent, ref LocalToParent localToParent, ref LocalToWorld localToWorld) =>
38. {
39. translation.Value = new float3(0,0,-10);
40. cameraRenderTranslation = localToWorld.Position;
41. });
42.  
43. //Update Camera Parent | Position | Rotation
44. Entities.ForEach((Entity entity, ref Translation translation, ref Rotation rotation, ref CameraComponent cameraComponent, ref Parent parent, ref LocalToWorld localToWorld) =>
45. {
46. parent.Value = cameraTargetEntities[0];
47. cameraRenderRotation = localToWorld.Forward;
48.  
49. });
50.  
51.  
52. //Set Camera Renderer Position And Rotation
53. Camera.main.transform.position = cameraRenderTranslation;
54. Camera.main.transform.forward = cameraRenderRotation;
55.  
56. //Dispose of Arrays
57. cameraTargetEntities.Dispose();
58. }
59. }
60.  
61.  
62. //Set Camera Renderer Position And Rotation
63. Camera.main.transform.position = cameraRenderTranslation;
64. Camera.main.transform.forward = cameraRenderRotation;
65.  
66. //Dispose of Arrays
67. cameraTargetEntities.Dispose();
68. }
69. }
70.  

 

isn't this hybrid since you convert monobehaviours?

 

Also, your system is called CaneraSystem instead of CameraSystem

 

Shmafoozius opps.
Chelvaric. I'm not using Monobehaviours. I'm using all ECS stuff. Only thing that is legacy is

Code (CSharp):

1. Camera.main.transform.position = cameraRenderTranslation;
2. Camera.main.transform.forward = cameraRenderRotation;

Thats why I called it 99% pure ecs. The camera is not a game object and is only entity. I have a game object called CameraRenderer that holds legacy camera stuff. Theres not ECS stuff being ran on that object.

 

Chelvaric I am using Converters for injecting entities but at runtime its 100% percent no monobehaviours and all ECS

 

Why don't you do things in a job and don't you pass your position/rotation through TransformAccess ?

Pure DOTS should be jobbable; everything you do here is on the main thread and therefore have no benefits over standard Monobehaviours.

 

Thanks for the advice alexandre-fiset. I don't have a lot of experience with DOTS. I'll look into it.