Am 22.11.2016 um 09:43 schrieb Mike Horvath:
> On 11/22/2016 3:31 AM, clipka wrote:
>>     min(
>>       convertLCH2RGB_R(y*200-100,sqrt(x*x+z*z)*100,atan2(x,z)*pi/180),
>>       convertLCH2RGB_G(y*200-100,sqrt(x*x+z*z)*100,atan2(x,z)*pi/180),
>>       convertLCH2RGB_B(y*200-100,sqrt(x*x+z*z)*100,atan2(x,z)*pi/180),
>>       1-convertLCH2RGB_R(y*200-100,sqrt(x*x+z*z)*100,atan2(x,z)*pi/180),
>>       1-convertLCH2RGB_G(y*200-100,sqrt(x*x+z*z)*100,atan2(x,z)*pi/180),
>>       1-convertLCH2RGB_B(y*200-100,sqrt(x*x+z*z)*100,atan2(x,z)*pi/180)
>>     )
> 
> I think the last parameter should be atan2(x,z)*180/pi because atan2
> returns radians and convertLCH2RGB_R expects degrees.

I guess you're right about this one.

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On 11/22/2016 4:44 AM, clipka wrote:
> Am 22.11.2016 um 09:43 schrieb Mike Horvath:
>> On 11/22/2016 3:31 AM, clipka wrote:
>>>     min(
>>>       convertLCH2RGB_R(y*200-100,sqrt(x*x+z*z)*100,atan2(x,z)*pi/180),
>>>       convertLCH2RGB_G(y*200-100,sqrt(x*x+z*z)*100,atan2(x,z)*pi/180),
>>>       convertLCH2RGB_B(y*200-100,sqrt(x*x+z*z)*100,atan2(x,z)*pi/180),
>>>       1-convertLCH2RGB_R(y*200-100,sqrt(x*x+z*z)*100,atan2(x,z)*pi/180),
>>>       1-convertLCH2RGB_G(y*200-100,sqrt(x*x+z*z)*100,atan2(x,z)*pi/180),
>>>       1-convertLCH2RGB_B(y*200-100,sqrt(x*x+z*z)*100,atan2(x,z)*pi/180)
>>>     )
>>
>> I think the last parameter should be atan2(x,z)*180/pi because atan2
>> returns radians and convertLCH2RGB_R expects degrees.
>
> I guess you're right about this one.
>

I am also not sure if using atan2 is good, since that only covers 90 
degrees, whereas the hue circle must use all 360 degrees.

Mike

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On 11/22/2016 7:59 PM, Mike Horvath wrote:
> On 11/22/2016 4:44 AM, clipka wrote:
>> Am 22.11.2016 um 09:43 schrieb Mike Horvath:
>>> On 11/22/2016 3:31 AM, clipka wrote:
>>>>     min(
>>>>       convertLCH2RGB_R(y*200-100,sqrt(x*x+z*z)*100,atan2(x,z)*pi/180),
>>>>       convertLCH2RGB_G(y*200-100,sqrt(x*x+z*z)*100,atan2(x,z)*pi/180),
>>>>       convertLCH2RGB_B(y*200-100,sqrt(x*x+z*z)*100,atan2(x,z)*pi/180),
>>>>
>>>> 1-convertLCH2RGB_R(y*200-100,sqrt(x*x+z*z)*100,atan2(x,z)*pi/180),
>>>>
>>>> 1-convertLCH2RGB_G(y*200-100,sqrt(x*x+z*z)*100,atan2(x,z)*pi/180),
>>>>       1-convertLCH2RGB_B(y*200-100,sqrt(x*x+z*z)*100,atan2(x,z)*pi/180)
>>>>     )
>>>
>>> I think the last parameter should be atan2(x,z)*180/pi because atan2
>>> returns radians and convertLCH2RGB_R expects degrees.
>>
>> I guess you're right about this one.
>>
>
> I am also not sure if using atan2 is good, since that only covers 90
> degrees, whereas the hue circle must use all 360 degrees.
>
> Mike

Sorry. Disregard that. It works.

Mike

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Am 23.11.2016 um 02:11 schrieb Mike Horvath:

>> I am also not sure if using atan2 is good, since that only covers 90
>> degrees, whereas the hue circle must use all 360 degrees.
>>
>> Mike
> 
> Sorry. Disregard that. It works.

That's the fun thing about `atan2(a,b)`: In contrast to `atan(a/b)` it
doesn't lose the information about the quadrant; it also avoids the
singularity at b=0 (provided a<>0).

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On 11/22/2016 3:31 AM, clipka wrote:
>> Here is the whole file again with your changes. The shape I get when I
>> render is that of a pointy cap. I don't know if that's correct or not.
>
> How would I know -- I'm not familiar with that colour model.
>
> Now you need to intersect that shape with the five others -- or use the
> combined function:
>
>     min(
>       convertLCH2RGB_R(y*200-100,sqrt(x*x+z*z)*100,atan2(x,z)*pi/180),
>       convertLCH2RGB_G(y*200-100,sqrt(x*x+z*z)*100,atan2(x,z)*pi/180),
>       convertLCH2RGB_B(y*200-100,sqrt(x*x+z*z)*100,atan2(x,z)*pi/180),
>       1-convertLCH2RGB_R(y*200-100,sqrt(x*x+z*z)*100,atan2(x,z)*pi/180),
>       1-convertLCH2RGB_G(y*200-100,sqrt(x*x+z*z)*100,atan2(x,z)*pi/180),
>       1-convertLCH2RGB_B(y*200-100,sqrt(x*x+z*z)*100,atan2(x,z)*pi/180)
>     )
>
> should do the job, I think.
>

Using "min" all I got was a cube. Switching to "max" instead, I got a 
shape... of some sort. I'm not sure it's the correct one. Check the 
thread in p.b.i and tell me if the images show the same object.

http://news.povray.org/583548b6%40news.povray.org

Mike

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I've attached the latest version of the script.

Mike

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Attachments:
Download 'cielch_color_solid_cylinder_isosurface.pov.txt' (9 KB)