GPU Pro 5

398 V 3D Engine Design

3.2.5 Parent Switch in Hierarchy

In a 3D engine we often need to modify objects’ parent-children relationship. One

condition that most engines try to enforce is that after changing the parent of

an object, the object’s global transformation remains unchanged. In other words,

we want to change the local transformation such that the global transformation

is still the same. Obviously, that forces us to recompute local TRS values of the

object whose parent we’re changing. Note that if the previous parent’s scale is

nonuniform and it’s different from the nonuniform scale of the new parent, the

skew of the object will change and as