It's correct. x, y, z are normalized value of coordination X, Y, Z. That means that given that PivotX = 0.5, for vertex at the right border
- X will be SizeX / 2 => x = X / SizeX = 0. 5 => x, y, z will run from -0.5 to 0.5
If we set pivot to 0, 0, 0 => x, y, z will run from 0 to 1.