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On Thu, 08 Aug 2002 16:10:01 +0200, ABX wrote:
> On 8 Aug 2002 10:00:51 -0400, Ron Parker <ron### [at] povray org> wrote:
>> > I can be wrong but I think they are only stored as floats. They are used in
>> > intersection tests as doubles probably. So it is rather that vertices are
>> > "aligned" to grid but still should be accurate the same way.
>>
>> For a very interesting definition of the word "grid."
>
> You mean it is rather checkered pattern of floating points ? ;-)
Well, no. See, the whole mantissa+exponent thing with floating point
numbers means that what you really have is a bunch of superimposed
finite-sized lattices at different scales, all (roughly) centered on
zero. So, the closer you get to zero the more dense the representable
points are. Doubles are the same way; the set just has more - and
larger - lattices.
Your primary point - that it doesn't matter as long as doubles are used
for the intersection test - is still valid. It's just not what most
people would call a "grid" since the representable points aren't all
spaced evenly.
--
#local R=rgb 99;#local P=R-R;#local F=pigment{gradient x}box{0,1pigment{gradient
y pigment_map{[.5F pigment_map{[.3R][.3F color_map{[.15red 99][.15P]}rotate z*45
translate x]}]#local H=pigment{gradient y color_map{[.5P][.5R]}scale 1/3}[.5F
pigment_map{[.3R][.3H][.7H][.7R]}]}}}camera{location.5-3*z}//only my opinions
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