Dynamic shape path for Lights

I intend to update the Lights.shapePath only to find out it's only a readonly. I don't want to burden myself with adding a lot of dots whenever I update the number of Vector3 in the shape path. This is because I intend to update the shape path via script. can we request for this to be available on the next update?

 

I would like to ask if this problem was fixed in the latest Unity 2020.1 version?

 

It seems no one is looking into this. A lot of the devs are having problems. See https://forum.unity.com/threads/2d-light-edit-shape-from-script.804033/ https://www.reddit.com/r/Unity2D/comments/c1piws/edit_shape_of_freeform_2d_light_from_code/

Why is the Shape path not available for us to change path size? This is quite limiting on the features we can do

 

@Chris_Chu any input on why this is a problem?

 

For anyone looking for a solution to this, I have handcrafted a workaround to make this somewhat functional.
Using reflection I can force the internal mesh to update with a given outer path:

Code (CSharp):

1.  
2.         var privateInstanceFlags = System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance;
3.  
4.         var lightType = Light.GetType();
5.         var shapeProperty = lightType.GetField("m_ShapePath", privateInstanceFlags);
6.         shapeProperty.SetValue(light, lightPath);
7.  
8.         lightType.GetMethod("UpdateMesh", privateInstanceFlags).Invoke(light, null);

Given that light is a reference to a Light2D instance and lightPath is the array of Vector3's you want to asign as outer path.

Using this at runtime and updating it every frame is not cheap, however, I see a lot of room for improvement when profiling:

Most notably, the internal LightUtility.GenerateShapeMesh method seems to generate a lot of allocations which should not be necessary. Presumably this is caused by using the LibTessDotNet library instead of a custom implementation.

@Chris_Chu Will you expose and optimise this code path in the near future?