NullReferenceException when changing a shader property during OnEnable of a parent component

Manuel Rauber

4 years ago
updated 4 years ago
Fixed

Hi Freya,

I may found a little bug.

Let's assume the following structure in the hierarchy:

ParentGameObject
- ChildObject with Shapes (Disc)

Whenever the ParentGameObject get's enabled, I use OnEnable to access the child Disc-Shape and set AngRadiansEnd.

However, this leads to a NullReferenceException:

NullReferenceException: Object reference not set to an instance of an object
Shapes.ShapeRenderer.ApplyProperties () (at Assets/Shapes/Scripts/Runtime/Components/ShapeRenderer.cs:254)
Shapes.ShapeRenderer.SetFloatNow (System.Int32 prop, System.Single value) (at Assets/Shapes/Scripts/Runtime/Components/ShapeRenderer.cs:273)
Shapes.Disc.set_AngRadiansEnd (System.Single value) (at Assets/Shapes/Scripts/Runtime/Components/Disc.cs:110)

I tracked it down to the following line:

rnd.SetPropertyBlock( Mpb );

rnd is null.

The "problem" is that rnd is set during OnEnable in the ShapeRenderer. However, the OnEnable of the parent is invoked before the OnEnable in the child object, that's why it's null in that case.

I can work around that, however I think it can be solved in Shapes and maybe do a null check before trying to access rnd.

Please let me know, if you need further information or a sample project for reproduction.

Reporting a bug? please specify Unity version:

2020.1.3f1

Reporting a bug? please specify Shapes version:

2.2.0

Reporting a bug? please specify Render Pipeline:

Replies 3

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Freya Holmér creator

4 years ago
Fixed

should be fixed now in the version after 2.2.0!

Reply Link

4 years ago

thanks for your fast answer. I hope it's ok to add another NullRef here that is kind of similar.

I've a script that gathers some ShapeRenderer and set their color. To reflect the color change in the editor, I use OnValidate:

    [SerializeField]
    private Color Color;

#if UNITY_EDITOR
    private void OnValidate()
    {
      UpdateColor();
    }
#endif

    private void UpdateColor()
    {
      Shapes?.ForEach(shape => shape.Color = Color);
    }

That leads to another NullReference exception, because my OnValidate is run before the Shapes OnValidate.

4 years ago
Planned

null checking unity objects is generally not very cheap, so unfortunately sometimes we get these edge cases! it's especially important in ApplyProperties since it's potentially called every frame

anyhow! I should be able to cover up this edge case, thanks for the report :)