This code crashes MegaPOV 0.4 and 0.5. (Oh, and it's not the tan(pi/2),
because changing the v-bound to pi-.001 or similar does not fix it.)

#include "colors.inc"
#version unofficial MegaPOV 0.5;

#declare KuenSurface = parametric {
   function (2*sqrt(1+u^2)*cos(u-atan2(u,1))*sin(v))/(1+u^2*sin(v)^2),
            (2*sqrt(1+u^2)*sin(u-atan2(u,1))*sin(v))/(1+u^2*sin(v)^2),
            ln(tan(.5*v))+(2*cos(v))/(1+u^2+sin(v)^2)
   <0,0>,<2*pi,pi>
   <-5,-5,-5>,<5,5,5>
}

camera { location <0,2,-8> look_at 0 }
light_source { <200,100,-300> color White*1.4 }
object { KuenSurface
   pigment { color Plum }
   finish { specular 10 roughness .003 }
}

Tanx

--
David Fontaine     <dav### [at] faricynet>     ICQ 55354965
Please visit my website: http://www.faricy.net/~davidf/

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David Fontaine <dav### [at] faricynet> wrote

> This code crashes MegaPOV 0.4 and 0.5. (Oh, and it's not the tan(pi/2),
> because changing the v-bound to pi-.001 or similar does not fix it.)
>
> #include "colors.inc"
> #version unofficial MegaPOV 0.5;
>
> #declare KuenSurface = parametric {
>    function (2*sqrt(1+u^2)*cos(u-atan2(u,1))*sin(v))/(1+u^2*sin(v)^2),
>             (2*sqrt(1+u^2)*sin(u-atan2(u,1))*sin(v))/(1+u^2*sin(v)^2),
>             ln(tan(.5*v))+(2*cos(v))/(1+u^2+sin(v)^2)
>    <0,0>,<2*pi,pi>
>    <-5,-5,-5>,<5,5,5>
> }
>

I get a "illegal operation" and program abort with WinMegaPOV
but not with DOS MegaPOV. Usually such things are vice versa,
(DJGPP compile seems more sensitive to memory mishandling) and
that makes me more curious.

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david sharp <dsh### [at] interportnet> wrote in message
news:3929d1ce@news.povray.org...
>
> David Fontaine <dav### [at] faricynet> wrote
>
> > This code crashes MegaPOV 0.4 and 0.5. (Oh, and it's not the tan(pi/2),
> > because changing the v-bound to pi-.001 or similar does not fix it.)
> >
> > #include "colors.inc"
> > #version unofficial MegaPOV 0.5;
> >
> > #declare KuenSurface = parametric {
> >    function (2*sqrt(1+u^2)*cos(u-atan2(u,1))*sin(v))/(1+u^2*sin(v)^2),
> >             (2*sqrt(1+u^2)*sin(u-atan2(u,1))*sin(v))/(1+u^2*sin(v)^2),
> >             ln(tan(.5*v))+(2*cos(v))/(1+u^2+sin(v)^2)
> >    <0,0>,<2*pi,pi>
> >    <-5,-5,-5>,<5,5,5>
> > }
> >

MEGAPOV caused an invalid page fault in
module MEGAPOV.EXE at 0167:0041df74.
Registers:
EAX=00000000 CS=0167 EIP=0041df74 EFLGS=00010246
EBX=0091f1e8 SS=016f ESP=01ddfed8 EBP=01ddff8c
ECX=00000000 DS=016f ESI=0091f858 FS=128f
EDX=00000015 ES=016f EDI=00000000 GS=0000
Bytes at CS:EIP:
ff 00 c3 90 90 90 90 90 90 90 90 90 56 8b 74 24
Stack dump:
0041d90c 00000000 00000000 0091f548 0091f6a8 0091f7c8 00000000 00000000
0091f858 00449026 0091f858 00000000 00000000 01ddff8c 816416d8 004509ee

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David Fontaine <dav### [at] faricynet> wrote
[ ... ]
> #include "colors.inc"
> #version unofficial MegaPOV 0.5;
>
> #declare KuenSurface = parametric {
>    function (2*sqrt(1+u^2)*cos(u-atan2(u,1))*sin(v))/(1+u^2*sin(v)^2),
>             (2*sqrt(1+u^2)*sin(u-atan2(u,1))*sin(v))/(1+u^2*sin(v)^2),
>             ln(tan(.5*v))+(2*cos(v))/(1+u^2+sin(v)^2)
>    <0,0>,<2*pi,pi>
>    <-5,-5,-5>,<5,5,5>
> }

Adding a "precompute" might let the surface to render.
(Still, of course, POV should not be crashing without it.)

For example:
 #declare KuenSurface = parametric {
    function (2*sqrt(1+u^2)*cos(u-atan2(u,1))*sin(v))/(1+u^2*sin(v)^2),
             (2*sqrt(1+u^2)*sin(u-atan2(u,1))*sin(v))/(1+u^2*sin(v)^2),
             ln(tan(.5*v))+(2*cos(v))/(1+u^2+sin(v)^2)
    <0,0>,<2*pi,pi>
    <-5,-5,-5>,<5,5,5>
   precompute 10, [x,y,z]
 }

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david sharp <dsh### [at] interportnet> wrote...
>
> Adding a "precompute" might let the surface to render.
> (Still, of course, POV should not be crashing without it.)

I agree.  Sorry if it seems like I'm ignoring you, but I don't really know
much about the isosurface code.  If I get a chance, though, I will see if I
can figure it out.

-Nathan

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david sharp wrote:

> Adding a "precompute" might let the surface to render.
> (Still, of course, POV should not be crashing without it.)

Tanx, i'll try it

--
David Fontaine     <dav### [at] faricynet>     ICQ 55354965
Please visit my website: http://www.faricy.net/~davidf/

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