[OpenSCAD] General approach

Parkinbot rudolf at digitaldocument.de
Mon Jul 8 10:11:40 EDT 2019


nophead wrote
>>
>> CGAL may be slow, but the architects' decision to build on a rational
>> number representation had good reasons .
> Yes but OpenSCAD gains zero advantage from this because it converts back
> to
> doubles and snaps to a grid and then feeds the results back to CGAL.

I am aware that CGAL only internally gains advantage of this and that it
would be a large progress (and amount of work), if OpenSCAD didn't dismiss
CGAL representations when looping, respectively if OpenSCAD also supported
transformations in CGAL-representation to avoid such conversions for all
intermediate steps. This would reduce the need of conversions to I/O
operations only. 

What I don't know is, how many loops OpenSCAD actually uses when it renders
a design. So what happens exactly for

difference()
{
  union() {A(); B();}
  C(); 
}

with A(), B(), C() defined as modules with visual output? Will OpenSCAD
really convert the result of the 
union twice before difference is called? 

And here: 

difference()
{
  rotate(45) 
  union() {A(); B();}
  C(); 
}

will OpenSCAD excute rotate in floating point representation? 



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