Take it from someone who just spent best part of a week figuring out how to write his own TFormVector TFormPoint and TFormNormal using quaternion math and no helper functions, these three functions are an absolute lifesaver.
When you see people saying "I don't care if X has shaders and all that cool stuff, I'm sticking with B3D." it's because of functions like this which make your life so much easier.
I like Ross's example, because I've always used TFormVector for that too. When you want your objects to be moved with the mouse but have a completely free camera, being able to convert a vector from camera space into world space so that you can transform the entity by it is just great.
When you see people saying "I don't care if X has shaders and all that cool stuff, I'm sticking with B3D." it's because of functions like this which make your life so much easier.
I like Ross's example, because I've always used TFormVector for that too. When you want your objects to be moved with the mouse but have a completely free camera, being able to convert a vector from camera space into world space so that you can transform the entity by it is just great.