On 15/09/2018 13:11, Mike Horvath wrote:
> On 9/15/2018 6:58 AM, Stephen wrote:
>> On 15/09/2018 11:43, Mike Horvath wrote:
>>> I have textures, but do not know how to orient them with respect to 
>>> the axial tilt, orbit and sun. Is anyone familiar with how to do this?
>>>
>>>
>>> Mike
>>
>> For Z up Left handed scenes.
>>
>>
>> texture {
>>    pigment {
>>      image_map{
>>        png "F:\Graphics\B3D Data\Maps\Planets\Earth\EarthMap2.png"
>>        interpolate 2
>>        map_type 1
>>      }
>>      rotate    <20.000,0.000,0.000>
>>    }
>>
>> Then for orientation in an orbit. Rotate the sphere the planet texture 
>> will follow.
>>
> 
> Thanks. But which direction does the axis tilt with respect to the Sun 
> on a given day?
> 
> 


Earth currently has an axial tilt of about 23.4° and the angle does not 
change. With respect to the Sun on a given day, it depends on there it 
is in its orbit.
https://en.wikipedia.org/wiki/Axial_tilt#Earth

So if you start your Planetarium at the summer or winter equinox. The 
mechanics will take care of themselves.
I think. :)



-- 

Regards
     Stephen

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