I have been working for a while to debug a shader I did on UE 4.9 until I discovered that the bug is coming from the engine itself.
Here is a simple test material: it contains a texture with a rectangle and some basic code to vertically offset the right part of the texture. When we do this some flicking texels appear on the offset axis. The more the offset value increases, the longer and more visible the flicking line becomes.
Can you please provide a fix for this in the release 4.10?
This is a UV precision issue and actually has more to do with the UVs of the Template Mesh in the Material Editor. If you take a Static Mesh Plane or Cube and in the Static Mesh Editor, under build settings, check Use Full Precision UVs to true and apply those new build settings. Your material will work as expected to a degree. There is always going to be a float point issue (very small and really visible only at close ranges) where the the UV math switches in your IF node.
