The origin of the "Y is up" system is obvious when you think about it:
2-D graphics naturally has the X-axis along the bottom of the screen
and the Y-axis up the left edge. When it became necessary to add a
Z-axis, it was natural to retain the convention for the X- and Y-axes.
However, the choice of having the Z-axis represent distance into the
screen (sensible enough when you consider Z-buffer rendering) is
inconvenient from a mathematical viewpoint, since this is a
left-handed coordinate system while vector analysis uses a
Personally, I don't care which axis points where -- but let's have a
right-handed coordinate system!
Dr Adrian F Clark <email@example.com>
PHONE: (+44) 206-872432 (direct) FAX: (+44) 206-872900
Dept ESE, University of Essex, Wivenhoe Park, Colchester, Essex, C04 3SQ, UK.