Le 14/08/2013 07:07, Anthony D. Baye a écrit :
> clipka <ano### [at] anonymousorg> wrote:
>> Am 14.08.2013 02:46, schrieb Bald Eagle:
>>
>>> Looks like you've run into the oft-encountered function/macro parse/render
>>> dichotomy.
>>>
>>> As I understand it, and folks can correct me if I'm wrong or mis-state this,
>>> functions are evaluated ONCE - at parse time.  So if you want something that
>>> gets updated during RENDERING, then you need to call the function with a MACRO.
>>
>> Um... no, not at all.
>>
>> - Macros are /always/ evaluated during parsing.
>>
>> - Functions may be evaluated either during parsing or during rendering,
>> depending on the context in which they are used.
> 
> So... Just not going to work?
> 
> The idea was to build up a progressively more complex function for the surface
> of the planet.  While I could do this using built-in patterns, that wasn't the
> point of the exercise.
> 
> I finally found the site where I first read about this:
> http://freespace.virgin.net/hugo.elias/models/m_landsp.htm
> 
> The great thing about it is: the more iterations you do, the better it gets.

The trick is in iterations: for once, you do not want to keep the real
sphere object, but start with a mesh of a sphere and move/scale parts of
it. As you are not to break any triangle, simply moving the vertex
should be enough.

I hope I will remember that thread & link long enough to expand my mesh
manipulation extension.
(now, I have to find an anisotropic random generator of 3D unit vectors...)


-- 
Just because nobody complains does not mean all parachutes are perfect.

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