Cubemaps using Default texture compression (DXT1) and packaged for Android ASTC will render with artifacts on the seams where the DDS cubemap was stitched together.

"Cubemaps set to HDR/HDR compressed are getting uploaded to device as uncompressed RGBA. These maps work, but obviously at a cost. Cubemaps set to Default (DXT1/5) are getting compressed to RGBA_ASTC_6x6, but have visible corruption along the bottom edge of all six cube facings."

In the test case provided, the resolution of the cubemap is low to have a more pronounced visual representation for the issue.

Some of the things to note that were discovered when testing.

  • Issue does not occur when packaged for a different compression format (i.e ETC1)
  • Issue does not occur if you set the cubemap's texture compression to HDR (which I believe is the correct format for cubemaps anyway)
  • Using the 'Full precision' options for the static mesh and the material have no effect on the issue.

I tested this on two separate android devices which are listed.

Steps to Reproduce

1. Download and Open attached project.
2. Package using the ASTC format and install to compatible device.

Outcome The cubemap renders with artifacts at the seams.

Expected Cubemap should render completely black.

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ComponentUE - Platform - Mobile
Affects Versions4.13.14.14
Target Fix4.15
CreatedOct 26, 2016
ResolvedNov 30, 2016
UpdatedSep 16, 2019
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