My Maya is in Z-Up. I have a light in my Maya scene that aims along -Z. It looks like this:
I’m getting the light’s forward vector by World Matrix -> Vector Product (Vector Matrix Product).
Then it’s connected to 3 Custom Float Attributes (Direction XYZ) on the root bone of the skeleton. The animation is baked and UE4 sees those custom attributes and imports them as animation curves.
I use these animation curves to drive a material, essentially acting as a light direction. It’s the bread and butter of my chosen art style.
However, there are a lot of differences in UE4. Maya in Z-Up has -Y as the forward facing direction. UE4 has +Y as the forward facing direction. So Z * -1 should solve that, but it doesn’t. The light in Maya is aiming down -Z, however in UE4 an object aims down +X. Like this:
How do I get a vector that will aim at the same vertex at the same direction in UE4 as it does in Maya? My characters have their own light directions for per-frame shading, and I need it to look the same in both packages. This is the last thing that’s causing issues.