Well, it’s your choice, but this stuff really isn’t that complicated. I’m not suggesting you read a book about vector math or something… You can learn it all by doing. That’s what I did. If I wanted to compute a cross-product of two vectors manually, I would look up the math on wikipedia. If I wanted to manually rotate a vector component by component, I would have to look it up as well. The math isn’t important, because there are functions (in UE4 like in every other engine) for pretty much everything (see RotateVector). You just need to know what they are good for and have some “spatial understanding”, so you know what tools you can use to accomplish certain things. If you have rigged a 3D model, you know that every bone has a transform that is relative to its parent bone, just like vertices are being positioned in bone-space. So global and local reference frames shouldn’t really be all that new to you.