Well it’s different, because it’s 2D inside of a 3D environment. Also a little history helps to understand why GP is they way it is. It started as a digital version of the old grease pencils that were used to draw on the glass of old style monitors in the early days of computer animation. Thus the name Grease Pencil. Then people started using it for storyboarding and quick animations. So, they decided to make it into a 2D animation system and the old GP in now called the Annotation Tool. It’s design also has to be flexible enough to draw using 3D meshes as the canvas and be interactive with the 3D environment.
