[Bf-committers] Boolean tool precision

[Chris Want]

Kent Mein wrote:
> In reply to Ken Hughes (khughes at pacific.edu):
> 
>> I've experimented with making the "equal to zero" tests scale based on 
>> the size of the values being compared, using the floating point numbers 
>> exponent and mantissa (see frexp() in math.h).  This gives much better 
>> results, but at the cost of speed: as much as 20% slower in some of my 
>> tests.
>>
>> I'm open to other suggestions how to handle this, or just live with one 
>> of these two options:  fast but possibly non-manifold, slower but almost 
>> always manifold.
>>
>> Ken
> 
> I vote for slower but more accurate.  Whenever I've used it I haven't
> been worried about the speed it could be 4 times slower and I wouldn't
> complain. ;)
> 
> Kent

My vote would be for committing this new code with a compile time flag
to enable/disable for now. I am a bit concerned about the speed, since
the C++ booleans are already much slower than the booleans created
by the megabool script.

Since most vertices are added on edges, maybe a good test would be to
adjust the "equal to zero" value as a proportion of the length of the
edge it is being added on (or if the vertex is being added in the
interior of a face, make it proportionate to the square root of the
area of the face). Anyways, I don't know the code well, so I don't
know how feasible this is.

Regards,
Chris