Transitioning from 2D to 3D requires conceptualizing depth. Goel introduces the mathematical projections necessary to display 3D objects onto flat 2D screens:
Pivoting objects around arbitrary coordinate points. computer graphics book by sushil goel
A detailed comparison of how pixels are mapped via a frame buffer versus how vector lines are drawn directly by an electron beam. Transitioning from 2D to 3D requires conceptualizing depth