[Job System, Example] Starting with simple optimizations : Using a NativeArray<struct> ?

Hi everyone,

Compile a Job with the burst compiler

To start with simple optimizations i followed this small tutorial.
https://docs.unity3d.com/Packages/com.unity.burst@0.2/manual/index.html#standalone-player-support

This simple example in the docs use a native array to run a job over the NativeArray<float>. That works fine.

Code (CSharp):

1. using Unity.Burst;
2. using Unity.Collections;
3. using Unity.Jobs;
4. using UnityEngine;
5.  
6. public class MyBurst2Behavior : MonoBehaviour
7. {
8.     void Start()
9.     {
10.         var input = new NativeArray<float>(10, Allocator.Persistent);
11.         var output = new NativeArray<float>(1, Allocator.Persistent);
12.         for (int i = 0; i < input.Length; i++) input[i] = 1.0f * i;
13.  
14.         var job = new MyJob
15.         {
16.             Input = input,
17.             Output = output
18.         };
19.         job.Schedule().Complete();
20.  
21.         Debug.Log("The result of the sum is: " + output[0]);
22.         input.Dispose();  output.Dispose();
23.     }
24.  
25.     [BurstCompile(CompileSynchronously = true)]
26.     private struct MyJob : IJob
27.     {
28.         [ReadOnly]
29.         public NativeArray<float> Input;
30.  
31.         [WriteOnly]
32.         public NativeArray<float> Output;
33.  
34.         public void Execute()
35.         {
36.             float result = 0.0f;
37.             for (int i = 0; i < Input.Length; i++)
38.             {
39.                 result += Input[i];
40.             }
41.             Output[0] = result;
42.         }
43.     }
44. }

But how to use NativeArray<struct>. in this case?

• Struct types
• Burst supports regular structs with any field with supported types.

This following example use a NativeArray<struct> instead of NativeArray<float>

Code (CSharp):

1. using System;
2. using Unity.Burst;
3. using Unity.Collections;
4. using Unity.Jobs;
5. using UnityEngine;
6. using Unity.Entities;
7.  
8. public class Test_NativeArrayStruct : MonoBehaviour {
9.  
10.     [Serializable]
11.     public struct theStruct {
12.         public int int1;
13.     }
14.  
15.     public NativeArray<theStruct> structNative = new NativeArray<theStruct>();
16.  
17.     private void Awake() {
18.         structNative = new NativeArray<theStruct>(10000, Allocator.Persistent);
19.     }
20.  
21.     private void Update() {
22.         var job = new MyJob {
23.             StructNative = structNative, // <------------ Fail ---------------
24.         };
25.         job.Schedule().Complete();
26.     }
27.  
28.     [BurstCompile(CompileSynchronously = true)]
29.     private struct MyJob : IJob {
30.  
31.         public theStruct[] StructNative;
32.         public void Execute() {
33.  
34.             for (int i = 0; i < StructNative.Length; i++) {
35.                 StructNative[i].int1 = 77;
36.             }
37.         }
38.     }
39.  
40.     private void OnDestroy() {
41.         structNative.Dispose();
42.     }
43. }
44.  

But it fail with the data conversion message:

StructNative = structNative,


Any ideas how this can be solved?

 

Code (CSharp):

1.     ....
2.     private struct MyJob : IJob {
3.         public NativeArray<theStruct> StructNative;
4.         ....

 

Thanks I over read it. -)

Unfortunately it cause "fail access because its not a variable error"

Code (csharp):

1. for (int i = 0; i < StructNative.Length; i++) {
2.                     StructNative[I].int1 = 77; // <--------------
3.     }

 

yeah to edit component data you should do the following:

Code (CSharp):

1. // get a copy of the data
2. var data = StructNative[i];
3. // do manipulations to the copy of the data
4. data.Int1 = 77;
5. // overwrite the existing data inside the StructNative array
6. StructNative[i] = data;
7.  

 

Seems that works for the code but not for the compiler. Simply crash mono in this case.. :-O

 

@mike_acton is correct to use a struct to encapsulate native arrays?

Right now i'm working on a Ear Clipping triangulator and I want to create something like this:

Code (CSharp):

1.     public struct PolygonJobData : IDisposable
2.     {
3.         [ReadOnly]
4.         public NativeArray<float2> Vertices;
5.         [ReadOnly]
6.         public int NumContournPoints;
7.         [ReadOnly]
8.         public NativeArray<int> StartPointsHoles;
9.         [ReadOnly]
10.         public NativeArray<int> NumPointsPerHole;
11.  
12.         public PolygonJobData (Vector2[] contourn, Vector2[][]holes, Allocator allocator)
13.         {
14.             ...
15.         }
16.  
17.         public void Dispose()
18.         {
19.             ...
20.         }
21.     }

 

Hi, dousi96. Did you manage to create an NativeArray with your PolygonJobData structure? I have the similar structure, but I can't create NativeArray, here is topic with my problem https://forum.unity.com/threads/job...t-types-error-invalidoperationexcepti.988558/ If you have any ideas, I will be very grateful