[EMAIL PROTECTED] wrote:
> For the interested, with MMA 6, on a Pentium 4 3.8Ghz:
>
> The code that Jon posted:
>
> Timing[Export["image-jon.pgm", [EMAIL PROTECTED]@Main[2, 100, 4]]]
> {80.565, "image-jon.pgm"}
That is not the code I posted: you are using Xah's parameters that generate
a different (and largely empty) scene.
> The code that Xah posted:
>
> Timing[Export["image-xah.pgm", [EMAIL PROTECTED]@Main[2, 100, 4.]]]
> {42.3186, "image-xah.pgm"}
>
> So Xah's code is about twice as fast as Jon's code, on my computer.
>
> The resulting files were identical (and both looked like pure white
> images; I thought they'd be interesting!).
Use 9, 512, 4 instead of 2, 100, 4 and you will get a more interesting image
of over 80,000 spheres with shadows and diffuse lighting.
This is a really important difference: half of that program is dedicated to
hierarchical spherical bounding volumes that are essential when tracing a
large number of spheres. Xah solved a completely different problem by
simplifying the scene to only 5 spheres, where bounding volumes are useless
and the performance characteristics of the program are wildly different.
--
Dr Jon D Harrop, Flying Frog Consultancy Ltd.
http://www.ffconsultancy.com/?u
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