[OpenSCAD] Functional OpenSCAD, working with vertex data

Parkinbot rudolf at parkinbot.com
Tue Jan 30 13:30:12 EST 2018


thehans wrote
> You say this belongs in a library, but is there a single library that
> has a properly implemented rounded cube?  Everyone's implementation is
> different and 99.9% of them are slow and/or poduce ugly geometry.
> This is why It should be standardized from the source.

Well I prefer libraries, which I write on my own, because they let me define
my own parameters and defaults and I can refer to the implementation. I
never understood why cube(), cylinder() and linear_extrude() are not
centered by default. And to be honest, I still don't know which prototypes
and defaults they exactly have. OK, this could be fixed by a proper
documentation ... 

We have discussed it before several times that OpenSCAD is missing a
(standard) library concept. Have a look at the libraries folder shipped with
OpenSCAD and you will discover pretty old stuff that hasn't been maintained
for years.
 
See my implementation of a rounded_cylinder() and how it deals with
conflicts between diameters and radii. It is pretty fast, but I have no way
to figure out, whether it is semantically equivalent with cylinder,
therefore I can't call cylinder() with all its parameters in case r_ is 0. 

$fa=.2;
$fs=.2;

CyR(r1=1, r2=6, h=7, r_=1.4, center = false); 
//CyR(h=12, r_=1, r1=6, d2=1); 

module CyR(r = 10, h=10, r_=1, d = undef, r1=undef, r2=undef, d1 = undef, d2
= undef, center=false)
{
  r1 = r1==undef?d1==undef?d==undef?r:d/2:d1/2:r1; 
  r2 = r2==undef?d2==undef?d==undef?r:d/2:d2/2:r2; 
  r1_=min(abs(h/4), abs(r1), abs(r_)); 
  r2_=min(abs(h/4), abs(r2), abs(r_)); 
  echo(r1, r2, r1_, r2_); 
  h=abs(h); 
  translate([0,0,(center?-h/2:0)])
    rotate_extrude() 
    intersection()
    {
      hull()
      {
        translate([r1-r1_, r1_]) circle(r1_); 
        translate([r2-r2_, h-r2_]) circle(r2_);  
       polygon([[0,0], [r1-r1_, r1_], [r2-r2_, h-r2_], [0,h]] ); 
      }
    square([max(r1,r2), h]); 
    }
}




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