🚀 go-pugleaf

In article <38F5FA5B.813A2438@cyberdude.com> dataman@cyberdude.com  writes:

>Thanks to  all for the fast answers .....
>
>Now, i understand why it's called "floating point" ....the precision changes
>...

No, the precision stays the same (6-7 digits for a typical float). You
have 6-7 digits of precision whether your number is very big or very small.

>
>I need float and not double ...Why ?
>I am building a 3d word , a big 3d world ..1000 km x 1000 km with 1 cm
>precision (= 100 000 000 units).

You could store your coordinates represented as cm. Then you have a number
between, say, 0 and 99999999. You can store that in a 32 bit or larger
integer such as a long.

>In this 3d world all the objects have a Point/Vector position (float x,y,z)
>...this is what the 3d engine needs (with relatively good precision)..and
>what i would like , is to keep in the abstract world representation. I want
>to avoid the conversion between world/3d engine co-ordinates ..

You can't have it both ways. float doesn't have the precision so for
a floating point type you would need a double. A 32 bit integer does have
the necessary precision but you may require some conversion.

-- 
-----------------------------------------
Lawrence Kirby | fred@genesis.demon.co.uk
Wilts, England | 70734.126@compuserve.com
-----------------------------------------