Not sure if anyone has come across this before. I have authored some seams and stitches onto a car seat in substance painter. I then exported them out and brought them into UE4 and compiled a shader. However, whenever i view the textures in the game viewport some of the seam lines seem to be wiggly
Try enabling the Use Full Precision UV’s in the Static Mesh Editor and see if that helps. UE4 will drop UV’s to use 16-bit precision instead of 32 bit as it is cheaper. However, in some cases, this can cause artifacts and that could be the reason that you are having issues. Check out the following Answer HUB post for some more info abou this.
Did you triangulate your mesh before importing it into Substance painter to do the textures? Sometimes differences in how the model is triangulated causes issues like that.
UPDATE I managed to fix this issue by doing a completely new UV layout. The original had an even textual density throughout the model so i just decided to give a dis-proportionally bigger share of the textual density to the arms of the chair. The then repainted the seams and brought into UE4 and Boom! Straight lines.