Why did the box move up when rotating after the translation? This looks different than translations during the translation step in the other slides.

aliceshan

The rotation is about the origin. If we translate first, then rotate, the translation will be taken into account in the rotation. I think this slide and the next is used to demonstrate that matrix multiplication is not commutative, so we need to keep in mind the order we apply the transormations.

Why did the box move up when rotating after the translation? This looks different than translations during the translation step in the other slides.

The rotation is about the origin. If we translate first, then rotate, the translation will be taken into account in the rotation. I think this slide and the next is used to demonstrate that matrix multiplication is not commutative, so we need to keep in mind the order we apply the transormations.