Thorsten Froehlich wrote in message <37f8d332@news.povray.org>...
>In article <37f865a9@news.povray.org> , Nieminen Juha <war### [at] cctutfi>
>wrote:
>
>>   Since each coordinate needs at least 2x16 bits (supposing that we don't
>> want to support images greater than 65536x65536 pixels), for an image
>> sized, let's say 1024x768 we would need 1024x768x4 bytes = 3 Megabytes.
>
>There are useful pseudo-random number generators out there that don't
repeat
>numbers until all numbers in the set of produced numbers have been
generated
>once (sorry, no idea how to put that in nice, short English).
>So you wouldn't need to store coordinates. And you can even go with a small
>pregenerated (built-in) set of random numbers, say 256 and then repeat that
>pattern. It would still be "random" enough. Of course a bitmap to store
>which pixels have been rendered can also be used.  No need for 3 MB, just
>use a better algorithm :-)


An appropriate random number generator should do the job.

>> Quite memory consuming, I think. Also accessing 9 Megabytes of memory at
>> random is slow...
>

POV-Win, at least, already appears to store the rendered image in memory, so
this wouldn't take much additional memory.  Also, it is possible, if slow,
to write each pixel to disk as it is rendered for most file formats.  If
necessary, the file can be saved uncompressed and then POV can compress it
after the scene has been rendered.

Mark

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