OpenEuphoria

Re: Repeat efficiency

• Posted by Derek Parnell <ddparnell at bigpond.com> Feb 18, 2003
• 462 views

On Tue, 18 Feb 2003 12:30:21 -0800, <xerox_irs at lvcm.com> wrote:

>
> I'm making a large z-buffer for a 3d program is dos.
>
> "zbuffer=repeat(repeat(0,1024),768)" --works fast but when I
>
> "zbuffer[y][x]=something"--it slows down really bad, probably because it 
> allocates a new double every time i do that
>
> I've tried
>
> "zbuffer=repeat(repeat(0,1024),768)+0.0" --takes a minute but makes
>
> "zbuffer[y][x]=something" alot faster like multiple times faster
>
> but the problem is that zbuffer must clear every frame.
>
> so something like this still wouldn't work
>
> constant clear_buffer=repeat(repeat(0,1024),768)+0.0
>
> while 1 do
> zbuffer=clear_buffer        --it would only be fast once !!!!! then make 
> the "zbuffer[y][x]=something" slow aagain
> --do 3d stuff here
> end while
>
> can you make the allocating cache bigger to whre if I allocate 8 megs 
> then free then it will not need to call the allocateing process for every 
> "zbuffer[y][x]=something", it would just take up the a part 8meg.
> So euphoria would not give the 8meg back so quitly after allocateing it 
> so i could use it quickly.
>
> How should I make the zbuffer ????????
>
> the only possibility is just to inverse the points every time, which 
> would slow it down alot
>
> zbuffer=repeat(repeat(0,1024),768)+0.0
>
> while 1 do
> zbuffer=-zbuffer
> --do 3d stuff here
> zbuffer=-zbuffer
> --do inverse 3d stuff here
> end while
>
> P.S. I want to keep it all in euphoria, and not use any asm so it can be 
> as readable and portable as possible.

The following code takes 0.11 seconds on my Windows 2000 , Intel P3, 550MHz
-----
sequence clearb
sequence zbuffer
atom e
e = time()     clearb  = repeat(repeat(0.0, 1024), 768)
zbuffer = clearb
for i = 1 to 768 do
   for j = 1 to 1024 do
      zbuffer[i][j] = 2.34 -- any value
   end for
end for
zbuffer = clearb
? time() - e

-- 


cheers,
Derek Parnell