Le 28/12/2013 14:41, Louis nous fit lire :
> After reading some tutorials and viewing examples I thought I understood
> isosurfaces, however when trying to create them myself, I run into problems.
> 
> I understand that function {(x*x + y*y + z*z - 1)} would create a sphere, but
> why doesn't function {(x*x + y*y + z*z + 1)} (plus instead of minus)?
> 
> According to my reasoning it should generate exactly the same sphere, using plus
> or minus should not make any difference in this formula, it only mirrors the
> coordinates which results in the same sphere right?
> 
> What am I missing?

The fact that the whole formula is evaluated to find the frontier of the
shape at the value of threshold (default to 0.0).

So, x*x + y*y + z*z - 1 threshold 0 is identical to x*x + y*y + z*z + 1
threshold 2.

Indeed, the simplest sphere is x*x + y*y + z*z, threshold r*r.
(r being the radius of the sphere).

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