WorldCoordinate3Way does incorrect axis Lerps

The Material Function WorldCoordinate3Way seems to incorrectly perform the Lerps from the axis contributions of the normals. An example is show here, with the left objects using the version that comes with Unreal. You can see in the top portion of the cube that the top face has bleed-in from the Y texture even though there should be no Y component in a Z plane. This causes very noticeable artifacts as can be seen.

The issue is that the amount of axis contribution of the normals is not taken properly into account for the Lerps. Here is a possible solution which corrects the issue. This replaces the inputs to the two LERP function in the existing material function.

Hey Dustums,

Thank you for providing a clear and reproducible bug report. I will return here once I have reported the bug and have concrete bug number to provide.

Cheers,

Hey Dustums,

I went ahead and entered the report for this issue UE-30964.

We appreciate the detail and the effort you put into the bug report, and once it has been addressed by the developers, they will decide the outcome for the issue. If fixed, it will be added to the release notes for an upcoming hotfix or major engine version.

Update: This has been fixed to be integrated into the official 4.12 release.

Cheers,