There are instances where HLODs will either generate a lightmap but not assign it to the correct Lightmap Coordinate index from the target lightmap setting in the HLOD outliner or the Lightmap will not be generated when enabled in the HLOD outliner. This is a regression of behavior from 4.12.5.

No lightmap generated: SM_Chair
When I had 4 setup to generate the lod none of them in 4.13 would generate a lightmap if I had auto-generated one manually for the chair. The proxy mesh has only a single UV for the texture layout.

Incorrect lightmap coordinate index: SM_Rock
When I have 4 of these setup and a I generate the lod the target lightmap does not assign correct. It stays at 0 in the proxy mesh, but in 4.12 was assigned correctly to the target lightmap coordinate index.

Tested in:
Working: 4.12.5 CL-3039270
Broken: 4.13 CL-3106830
Broken: 4.14 Dev-Main CL-3109838

Steps to Reproduce

1. Enable HLODs in the World Settings
2. Add a couple of static meshes to the scene with or without a second uv for lightmap (I used SM_Rock and SM_Chair from Starter Content for these tests)
3. In the HLOD Outliner enable generate Lightmap UV
4. Then click Generate Clusters
5. Then click Generate Proxy Meshes
6. Select and open the Proxy Mesh

Regression: Yes

Results: In 4.12 the lightmap would be generated and assigned to the proxy mesh in the correct lightmap coordinate index

Expected: The lightmap should be generated and assigned to the target lightmap coordinate index.

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Fix Commit3115893
CreatedSep 6, 2016
ResolvedSep 7, 2016
UpdatedApr 27, 2018