Matrix4::new_orthographic doesn't let you make upside-down projections.

[icefoxen]

Namely, if you want a projection where +y is down, you do something like... Matrix4::new_orthographic(0, 1, 1, 0, 1, 0) (left, right, top, bottom, near, far). But it panics when you try to do that, saying the top-left corner must be higher than the bottom-left corner.

This isn't really a problem, but is an inconvenience.

[sebcrozet]

I agree this is an useless limitation. It will be fixed in the next minor release of nalgebra.