In article <1179665460.4706.11.camel@jonathan-desktop>, Jonathan Osuch <osuchj@avalon.net> writes:
There is some coe in line3d.c that sets and clears this bit, but apparently noone else pays attention to it except as a side effect of comparing user float flag to 1 or 0.
What's the purpose of this second bit?
To force the use of floating point routines in the line3d.c module when the ZVIEWER variable is less than 80. [...]
The problem is that the code that uses this doesn't check explicitly for bit 2, just whether or not user float flag is non-zero. So its not clear which code is just supposed to run when user float flag is non-zero and which code is supposed to run when the 2nd bit is set. Furthermore, setting this second bit causes other code depending on the user float flag to become unpredictable as some of the code tests user float flag being non-zero and some of the code tests user float flag being exactly 1. -- "The Direct3D Graphics Pipeline" -- DirectX 9 draft available for download <http://www.xmission.com/~legalize/book/download/index.html> Legalize Adulthood! <http://blogs.xmission.com/legalize/>