Area disk light not working?

Is the receiving plane set to receive GI? Does it work if you change to a rect area light?

 

GI is short for Global Illumination which is what baking the light will calculate and store in lightmaps and probes.
Contribute GI Include the GameObject when precomputing lighting data (from https://docs.unity3d.com/Manual/StaticObjects.html)

 

Baked disc area lights work just fine in 2019.3.10f1, I've tried it myself. As @KEngelstoft said, make sure that your plane is set to Receive Global Illumination from lightmaps in the Mesh Renderer component.

 

I am not sure I am following: what has never worked in 2018.4? Could you please clarify?

 

Are you by any chance using custom falloff scripts for your baked lights? If so, you'd have to modify the switch statement to take disc lights into account. Here's a modified version of the script:

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4. using UnityEngine.Experimental.GlobalIllumination;
5. using UnityEngine.SceneManagement;
6. [ExecuteInEditMode]
7. public class ExtractFalloff : MonoBehaviour
8. {
9.     public void OnEnable()
10.     {
11.         Lightmapping.RequestLightsDelegate testDel = (Light[] requests, Unity.Collections.NativeArray<LightDataGI> lightsOutput) =>
12.         {
13.             DirectionalLight dLight = new DirectionalLight();
14.             PointLight point = new PointLight();
15.             SpotLight spot = new SpotLight();
16.             RectangleLight rect = new RectangleLight();
17.             DiscLight disc = new DiscLight();
18.             LightDataGI ld = new LightDataGI();
19.            
20.             for (int i = 0; i < requests.Length; i++)
21.             {
22.                 Light l = requests[i];
23.                 switch (l.type)
24.                 {
25.                     case UnityEngine.LightType.Directional: LightmapperUtils.Extract(l, ref dLight); ld.Init(ref dLight); break;
26.                     case UnityEngine.LightType.Point: LightmapperUtils.Extract(l, ref point); ld.Init(ref point); break;
27.                     case UnityEngine.LightType.Spot: LightmapperUtils.Extract(l, ref spot); ld.Init(ref spot); break;
28.                     case UnityEngine.LightType.Area: LightmapperUtils.Extract(l, ref rect); ld.Init(ref rect); break;
29.                     case UnityEngine.LightType.Disc: LightmapperUtils.Extract(l, ref disc); ld.Init(ref disc); break;
30.                     default: ld.InitNoBake(l.GetInstanceID()); break;
31.                 }
32.           ld.falloff = FalloffType.InverseSquared;
33.                 lightsOutput[i] = ld;
34.             }
35.         };
36.         Lightmapping.SetDelegate(testDel);
37.     }
38.     void OnDisable()
39.     {
40.         Lightmapping.ResetDelegate();
41.     }
42. }

 

Glad to hear it is working for you! We will update the bespoke Unity manual page with the updated version of the script soon.