Am 08.12.2024 um 17:25 schrieb kurtz le pirate:

> 
> I also have problems with PrettyBall_1. 3 isosurfaces. Two are ok. The 
> third really doesn't match. Yet the code is/looks ok.
> 
> 
Indeed, this is actually a very strange difference between POV and 
MathMod. In the top row are the three objects as isosurfaces in POV, 
below are the objects exported from MathMod with the same formulae. The 
second and third objects match quite well, while the first one is 
completely different. I cannot judge whether the error is in POV or in 
MathMod.

If you compare the two objects on the right and in the centre in the 
bottom row (MathMod), you may get the impression that the one on the 
right could be created from the middle one as a point reflection at the 
origin (scale <-1,-1,-1>) and in fact both are largely congruent after 
this operation. You will get the correct result with POV if you create 
the first object from the centre one with the mentioned scaling or 
change the definition of GyroidLatice_1 as follows:

#declare GyroidLatice_1 = function {
    select(isoCondition(x,y,z),Iso3(-x,-y,-z),1) + 
exp(isoCondition(x,y,z)/5)
//   select(isoCondition(x,y,z),Iso2(x,y,z),1)// - 
exp(isoCondition(x,y,z)/5)
}


Best regards
Michael

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