[Bug-gnubg] 3D board quirks on Mac OS X solved

[Olivier Baur]

Hi all!

I've found where the strange image problems I had with 3D Boards come 
from: some sqrt's returning NaN's in the routines that compute rounded 
corner vertex coordinates. On the Mac, the following code:

latitude = (float)sin(angle2) * lip;
new_radius = (float)sqrt((lip * lip) - (latitude * latitude));

will return NaN in new_radius when angle2 == PI / 2.

I guess this must come from some rounding problem when converting 
sin(angle2) * lip  from double to float (?)

I've safe-guarded all risky calls to sqrt (ie, that involve a 
substraction) with some MAX (0.0f, ...) macro call (in drawboard3d.c 
and misc3d.c)

Change not comitted yet.


-- Olivier