Fixed point info/source?

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2 total messages Started by Patrik Hoyer Sun, 07 Jan 1996 15:02

#2167

Author: Patrik Hoyer
Date: Sun, 07 Jan 1996 15:02

19 lines
1142 bytes

Hi,

I'm planning on using fixed point math for my 3d engine. (For those of you
ready to recommend floating point on the pentium of powerpc... I'm
targeting low end computers. No texture mapping, just flat-shaded
polygons.) Now, I'd like to find some info on problems and solutions
relating to using fixed instead of floating point. (The problems of
overflow, and that of numbers close to zero losing all precision comes to
mind). Source code would also help, I guess. I'd prefer online sources of
information (cheap) but if you know of any good books covering the subject
feel free to recommend them too!

Thanks!

-Patrik

-- 
Patrik Hoyer
<phoyer@snakemail.hut.fi>

Re: Fixed point info/source?

#2168

Author: Michael Kraemer
Date: Mon, 08 Jan 1996 15:54

17 lines
1358 bytes

In article <phoyer-0701961703010001@192.0.2.1>, phoyer@snakemail.hut.fi (Patrik Hoyer) writes:
> Hi,
> 
> I'm planning on using fixed point math for my 3d engine. (For those of you
> ready to recommend floating point on the pentium of powerpc... I'm
> targeting low end computers. No texture mapping, just flat-shaded
> polygons.) Now, I'd like to find some info on problems and solutions
> relating to using fixed instead of floating point. (The problems of
> overflow, and that of numbers close to zero losing all precision comes to
> mind). Source code would also help, I guess. I'd prefer online sources of
> information (cheap) but if you know of any good books covering the subject
> feel free to recommend them too!
> 

You might look at the Motorola Fast Floating Point (FFP) package.
It runs on plain 68000s and uses 24bit mantissa, 7 bit exponent, 1 bit sign.
It comes standard with every Amiga and should also be available from Motorola.

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