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View Full Version : The Chronicles of Nurnia: the Greeble, the Nurnie, and the algorithm

 Kuroyume016105-29-2009, 03:51 AMI'm having a 'witch' of a time finding information on or algorithms related to creating greebles and nurnies on 3D geometry programmatically. The wiki says something about Fractal algorithms being used: Similar algorithms are used in the creation of fractal surfaces. Nothing at ACM (SIGGRAPH) - but I may try a more indirect search like "3D surface detail" instead of expecting usage of the universally industry standard terms 'greeble' and 'nurnie'. Thanks for any leads. Robert
Ian Jones
05-29-2009, 11:17 AM
It's a simple concept really. Fractal really just translates to recursive. Both words sound impressive but it is a deadly simple concept. Take a polygon, divide -> extrude... then recursively divide -> extrude the result to the number of desired levels.

Kuroyume0161
05-29-2009, 03:32 PM
I know what fractals are and what recursion is (I am a programmer, yes?). ;)

But there is more to it than simple recursive subdivision. For instance, users might like not only to have the surface subdivided (and then raised or lowered) but bevelled or using various shapes (box, 'c', etc.) in the process. And there should be some amount of user control in the recursive randomness.

I was just hoping there was more information on how this might be best approached overall - interface, variables, and variation.

Thanks,
Robert

Ian Jones
05-30-2009, 11:13 AM
Sorry, wasn't sure what level of conceptual understanding you had.

Hirni_NG
05-30-2009, 03:15 PM
I guess what you are looking for is a replacement syntax much like an L-system. A set of rules is applied to an unknown input. These rules can then be applied recursively. In case of greeble, the set of domain specific rules would consist of such things as shrink, extrude, insert object or whatever one can come up with which then can be combined to make for some user defined and intersting greebles.

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