Hi,
I think thats a common question, but i couldnt find a clear answer on the internet :
I know that the internal default forward vector from UE4 is +X. But all meshes that i found in the example projects (e.g. the blue template character mesh), use +Y as the forward direction (and rotate it later in the blueprint). Whats the reason behind this?
Should i import my meshes with +X or +Y as the forward direction into UE4? Whats the best practice?
I’d stick to X. If things were being rotated its is probably because somebody wanted to pretend to unify the orientations without the risk of changing content.
Generally it doesn’t really matter, it can just make your life easier knowing things like this to be assumed for all meshes.
I use X-axis as forward atm, because i can get with " Mesh->GetForwardVector() " the forward-vector easily.
This works fine with static-meshes, but i have some problems with skeletal meshes.
First, the skeletal mesh display window always faces to -Y, because if the forward vector of the character is +Y, the character will face the camera. But if my forward vector is +X, he will face sideways. Thats not optimal. And in the retarget manager, the T-pose is shown from the side if the character has +X as a forward vector. Thats not good either.
I dont want to work against the engine. It seems that the forward-vector for the asset management is +Y and engine intern its +X. Thats inconsistent 
I want it to be consistent and i dont want to have problems in the future.
Can someone tell me the reason behind the different forward vectors? Is +X as forward an old engine relic? because unreal is the only software that i know, which uses +X as forward.
The skeletal meshes have a 90 degree offset because the authoring package is Autodesk Maya, which has a different coordinate system to Unreal. It’s simply a limitation when converting between coordinate systems during import.