Sorry about that :) In CG and gamedev I've seen "Y is up" a lot more, to the extent that the "depth buffer" is usually called the "Z buffer".
I don't know how this came to be. You make a very good point that XY as the floor makes a lot of sense, especially if you're coming from the context of "I'm drawing a floorplan on a horizontal table" - the floorplan matches the orientation of the actual floor so XY is the most natural choice.
I suppose for a similar reason CG adopted the "XY is a wall" convention, since you start with XY on the screen (a vertical plane in front of you) and only later add depth?
I can see how using Z as the depth axis for the 2d coordinate system of the screen is a natural way to go for a programmer. Maybe I can lay my monitor flat on a glass desk and lay on the floor ;-)
I've been reading the book and enjoying it so far. Thank you.
I don't know how this came to be. You make a very good point that XY as the floor makes a lot of sense, especially if you're coming from the context of "I'm drawing a floorplan on a horizontal table" - the floorplan matches the orientation of the actual floor so XY is the most natural choice.
I suppose for a similar reason CG adopted the "XY is a wall" convention, since you start with XY on the screen (a vertical plane in front of you) and only later add depth?