How do I negatively scale a dynamic mesh in blueprint? (flipped normal map problem)

Development Programming & Scripting
, , ,
1

This seems simple. I set up a dynamic mesh component. Use nodes “copy mesh from static mesh” and then “scale mesh” to scale the dynamic mesh -1 on the X axis. The resulting dynamic mesh has a flipped normal map with shadows going the wrong direction. I can’t find a way to fix it programmatically.

The only half-fix I’ve found is to copy the dynamic mesh back to a static, then manually use the modelling tools “Nrmls” tool, then check “Fix inconsistet normals” and apply. Then the mesh will have a correct normal map again. Then you could copy it back to the dynamic mesh. However, it’s really throwing a stick in the gears of my process that I can’t just do that part programmatically on the dynamic object. So many “normals” and “uvs” nodes available, but none I can find to fix this problem which makes negative scaling pretty much useless. Even worse: running the Nrmls tool on multiple meshes at once invariably crashes the whole engine.
Please Help…

2

In case anyone was interested, I found a workaround. On the dynamic mesh, use the node “apply mesh mirror” to append a mirrored copy of the mesh next to the existing mesh. The mirror will have a correct normal map. From there, you can apply a plane cut node to cut off the original non-mirrored mesh, and a ‘translate mesh’ node to reposition the mirrored copy back to the proper origin. It works, but I’m on the fence about on whether to call this a “solution.”