MichaelJF <fri### [at] t-onlinede> wrote:

Well, the red and orange are looking good!

I'm not sure what's happening with MW's method, but I was just making a quick
suggestion.

The surface obviously extends infinitely in the +/-y directions, and so the
select is just there to trim the function.
I believe we can exclude that and just rely on the contained_by box.

IsoExterior (10*x/15),y,z) just scales the function in the x direction.
I'd take that out and use scale to take care of that part.

I'm just guessing here, but what if you then try something like:
IsoExterior (abs (x) - 0.01, abs (y) - 0.01, abs (z) - 0.01)

maybe also experiment with subtracting from f_r (x, y, z)
(include functions.inc)

try changing the threshold from 0 to 0.01

There's a lot of tricky things that have to be done to get certain functions to
work well with isosurfaces in POV-Ray vs other software packages

Maybe take a look further upstream at the preceding functions in the daisy chain
to see if a better gradient can be fashioned.

Define a set of y axes across the xz plane in the AABB, and graph the function
along those y-axes and see what pops out.

- BW


> This all works very fine, but Mike Williams' approach (dark purple)
> looks a little strange:
>
> #declare DevilsPlateD = function (x,y,z) {
>       select (
> -(-24/10-y)*(y-44/10),(abs(IsoExterior((10*x/15),y,z))-0.01) ,1)
> }
> isosurface {
>     function {
>        DevilsPlateD(x,y,z)
>     }
>     contained_by { box { <-45/10,-25/10,-75/10>,<45/10,45/10,75/10> } }
>     threshold 0.0
> //   open
>     max_gradient 1000000
>     pigment { colour DarkPurple }
> }
>
> All values for max_gradient are adjusted according to the log.
> max_trace_level was at maximum (256).
>
> I have no idea what happens here.
>
> Best regards
> Michael

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