On Tue, 25 May 1999 14:30:43 +0200 (CDT), Jan Danielsson wrote:
>How should a multithreaded povray work?
>
>I guess the user specifies how many threads he/she wants, then what?
>
>Should the threads render lines, or should it devide to picture in to
>'imageheight devided by threads' blocks and render them?

Ignoring for a moment how hard any multithreaded design will be to 
implement in practice, I think a thread should always just do whichever
scanline is next when it gets ready to go.  For one thing, this will 
help minimize the amount of rendered information that is hanging 
around in memory without having been written to the file.  For another,
it will do a more effective job of balancing the load between the 
threads.  Skyvase, for example, spends most of its time in the bottom 
half of the image.

You could, of course, run a low-resolution test render first and 
assign blocks of the image based on the histogram results.

Okay, now let's stop ignoring how hard a multithreaded design is.  Can
I ask all of you "we need SMP so we need threads" people what's wrong 
with plain ol' fork?  Yeah, Winblows doesn't support fork natively, 
but that seems like something Mickeysoft should fix.  Or just install
a real OS on your fancy SMP machine.

Post a reply to this message