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Nieminen Mika wrote:
>
> Peter Popov <pet### [at] usa net> wrote:
> : Merge of spheres - the problems typical for the union of spheres are
> : avoided, but merge is really slow as is.
>
> Not really true. I wonder why this delusion persists.
> See http://www.students.tut.fi/~warp/povVFAQ.html#csgspeed
>
> (Everyone keeps saying that merge is (always) a lot slower than union,
> but no-one has ever said why. Or even proved it.)
I have the following script that shows the merge operation taking 2 times
longer than a union of the same objects. I did recieve similar results as
you did with the example you gave but this example obviously takes longer
though I cannot offer an explaination as to why.
Rendered at 120x100 no AA
union time: min. 3 sec. 9
merge time: min. 6 sec. 21
union {
// merge {
#declare A = 0;
#while ( A < 10)
#declare B = 0;
#while ( B < 10)
#declare C = 0;
#while ( C < 10)
box { -.5, .5
pigment { rgbf .9}
translate<-5,-5,-5>
translate <0.99*A, 0.99*B, 0.99*C>
}
#declare C = C + 1;
#end
#declare B = B + 1;
#end
#declare A = A + 1;
#end
}
global_settings { max_trace_level 85}
camera { location<2.5,5,-15> look_at 0}
light_source { <30,100,100> rgb 1}
light_source { <-0,10,-200> rgb 1}
background { rgb 1}
--
Ken Tyler
mailto://tylereng@pacbell.net
http://home.pacbell.net/tylereng/links.htm
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